IPTraf User's Manual Version @@version@@ 1997 2003 Gerard Paul Java This manual is released under the terms of the GNU Free Documentation License of March, 2000 as published by the Free Software Foundation, reproduced in this manual as Appendix B. IPTraf is open-source software released under the terms of the GNU General Public License version 2 or any later version as published by the Free Software Foundation, reproduced in the LICENSE file in the distribution's top-level directory. The accomanying software and the information contained in this document are provided "AS IS" without warranty of any kind, express or implied, including, without limitation, the implied warranties of mercantability or fitness for any particular purpose. In no event shall the author be liable for any indirect, special, consequential, or incidental damages arising from the use of this manual or the accompanying software even if the author has been advised of the possibility of such damages. Linux is a registered trademark of Linus Torvalds. Pentium is a registered trademark of Intel Corporation. All other trademarks are property of their respective owners. Some structure declarations were based on code copyrighted by the Regents of the University of California. Token Ring parsing code based on the Token Ring packet construction code in the Linux 2.2 kernel. About This Document This document contains the instructions on how to use the IPTraf network monitoring software version @@major@@. This manual details the different statistical facilities, the user interface, and the important features of the software. For Additional Information See the included README file for summarized and late-breaking information. Also read the RELEASE-NOTES file for important new information about this new version. The CHANGES file contains a record of the changes made to the software since 1.0.0. README.rvnamed contains information on the rvnamed reverse resolution program. See the other README files for support and development information. Document Conventions The following symbols and typefaces are used throughout this manual: [ ] items in brackets are optional. Brackets also denote items that may or may not be displayed onscreen depending on settings or conditions. { } curly braces enclose items you choose from | the vertical bar separates choices in curly braces normal monospace normal monospace text in syntax specifications should be typed in exactly as presented. Because UNIX and variants are case-sensitive, case must be preserved. Monospace is also used in presenting items that appear on the screen. monospace italics italics in syntax specifications indicate items that are to be replaced with an actual item (e.g. interface should be replaced with an actual interface name, like eth0). Additional information appears distinctively set apart from the main text. This information includes Notes, Tips, or Technical Notes. Notes are additional pieces of information that may be useful or may clarify the preceeding paragraphs of the manual. Tips provide shortcuts, clarify tasks that may not be immediately obvious, or provide references to additional sources of information. Technical notes are explanations of a more technical nature and may be of more use to programmers and advanced users. Getting Started About IPTraf IPTraf is a network monitoring utility and traffic analyzer for IP networks. It intercepts packets and returns data about captured the network traffic in various statistical facilities. IPTraf comes with these major features: An IP traffic monitor that shows TCP connection information (hosts, packet/byte counts, flags, window sizes), and color-coded information about other IP packets Statistics (counts and load rates) for network interfaces in general and detailed views Statistics per TCP/UDP port Statistical breakdown according to packet sizes A LAN host monitor that returns counts and loads per detected MAC address A powerful filtering system for users to view only interesting traffic Logging An asynchronous DNS resolver for the IP traffic monitor A text-based, full-color, menu-driven user interface suitable for use on all Linux systems with terminals, especially Linux consoles and color xterms Easy configuration Fully software-based. No additional hardware required Basic knowledge of the important TCP/IP protocols (IP, TCP, UDP, ICMP, etc.) is necessary for you to best understand the information generated by the program. Installation IPTraf is most readily available on the Internet, but some may receive it on a diskette. Here are the instructions for both types of distributions. System Requirements IPTraf requires: Hardware Requirements 16 megabytes of physical RAM (more recommended, at least 64 MB for very busy networks) 2 megabytes of free disk space for installation (more will be needed if you log high amounts of traffic over time) Pentium-class processor or higher (Pentium-II 200 MHz or higher recommended) or equivalent. One or more of the supported network interfaces. Operating System Requirements Linux kernel 2.2.0 or higher GNU C Library 2.1 or later ncurses 4.2 or later with the complete terminfo database in /usr/share/terminfo. Support for linux, vt100, xterm, xterm-color recommended. Compilation Requirements The following components are required when compiling IPTraf from the source code. gcc 2.7.2.3 or later GNU C (glibc) development library 2.1 or later ncurses development libraries 4.2 or later Availability IPTraf can be downloaded from the Internet from the official FTP site at ftp://iptraf.seul.org/pub/iptraf/ . The software is available in source form in compressed .tar.gz files named iptraf-x.y.z.tar.gz where x.y.z is the version number. Precompiled ready-to-run software is available in the iptraf-x.y.z.machinetype.bin.tar.gz files. (machinetype indicates what platform the precompiled binaries run on. The official distribution will only be for the Intel x86 architecture indicated as i386.) Installing Downloaded Packages You will need to have GNU tar and GNU zip installed. All modern Linux installations already have these utilities ready. Decompress the .tar.gz file by entering tar zxvf iptraf-x.y.z.tar.gz for the source code or tar zxvf iptraf-x.y.z.i386.bin.tar.gz for the precompiled x86 programs. If your tar doesn't support the z option, you can separately decompress the .tar.gz file then extract the resulting .tar archive. gunzip iptraf-x.y.z.tar.gz tar xvf iptraf-x.y.z.tar This will decompress the sources into a directory called iptraf-x.y.z (source code) or iptraf-x.y.z.bin (precompiled). (x.y.z here should be the IPTraf version number you're installing, like @@version@@). Change to the created top level directory. To compile and install the software, run the Setup program by entering ./Setup while you are logged in as root. The Setup script will recognize the source distribution and compile the software before installing. It will immediately install a precompiled distribution. The resulting binaries will be placed in the /usr/local/bin directory. All needed directories will also be created. After installation, you will be asked if you want to read the RELEASE-NOTES file. It is recommended that you do so at that point, since the RELEASE-NOTES file contains important information about the new version. Installing a Floppy Distribution If you received IPTraf on a diskette, the sources are already decompressed. The diskette is in Second Extended filesystem format. Perform the following steps to install the software. Insert the floppy in the drive. Mount the floppy on an empty directory. For example, to mount the floppy in the first floppy drive under a directory called /mnt, enter mount -t ext2 /dev/fd0 /mnt This assumes your floppy is in /dev/fd0. You can use any empty directory in place of /mnt. With most Linux installations, this will work fine. After mounting, change to the /mnt (or whatever) directory. Enter ./Setup while logged in as root. Setup will determine whether the diskette contains a source code distribution or ready-to-run precompiled software. This will copy the binaries to /usr/local/bin, and create the necessary working directories. Unmount the diskette by typing umount /mnt (That's umount, not unmount.) You can then eject the diskette. Store it in a safe place. You will also be asked if you want to view the RELEASE-NOTES file. It is recommended that you do so at that point. In both cases (downloaded and floppy), the installation will store the program in /usr/local/bin with the binaries owned by user root, readable, writable, and executable by the owner, no permissions for the group, no permissions for all others. (700 octal, or -rwx------). Note You must be root to do the installation. The old style of installation (cd src;make install) is still supported. Be sure /usr/local/bin is included in your environment's PATH variable. You can edit the appropriate command in your login customization file (.profile for the Bourne-type shells, .cshrc for the C shell and its relatives). Upgrading from Earlier Versions IPTraf 3.0 is a major revision from IPTraf 2.7. The filter subsystem has been completely redesigned and as such, is incompatible with previous filter formats. Therefore old IPTraf filters can no longer be used. The installation procedure for IPTraf 3.0 will rename the filter list files but not delete them. If you install a distribution package (e.g. RPM, dpkg), old filters may still appear in the filter selection list but the new IPTraf version will be unable to load them. Starting and Stopping IPTraf After installation, you can start the program by simply entering iptraf at the shell prompt. You will see a copyright notice, with an instruction to press any key to get started. Just press any character key, and you will be immediately taken to the main menu. All major functions of the program are found there. Entering the IPTraf command without any command-line parameters brings up the program's main menu. From there, you can select the facilities you want. IPTraf determines and makes use of the maximum number of lines and columns on the terminal. Note IPTraf does not have a SIGWINCH handler; it does not adjust itself when an xterm or some other X terminal is resized. Technical note IPTraf needs to refer to the terminfo database in /usr/share/terminfo. If the supplied executable program fails with Error opening terminal, your terminfo database may be located somewhere else. You can control the terminfo search path by using the TERMINFO environment variable. For example, if you're using the sh or bash shell, and your terminfo database is in /usr/lib/terminfo (typical for Slackware distributions), you can use the commands: TERMINFO=/usr/lib/terminfo export TERMINFO You can place these commands in your ~/.profile or the systemwide /etc/profile startup files. You can also create a symbolic link named /usr/share/terminfo to let it point to your existing terminfo (assuming again your terminfo is in /usr/lib/terminfo): ln -s /usr/lib/terminfo /usr/share/terminfo Or you can recompile your program to use your existing ncurses library installation. If you do this, make sure you have ncurses 4.2 or later. Command-line Options IPTraf has a few optional command-line parameters. As with most UNIX commands, IPTraf command-line parameters are case-sensitive (-l is NOT the same as -L). The following command-line parameters can be supplied to the iptraf command: -i iface causes the IP traffic monitor to start immediately on the specified interface. If -i all is specified, all interfaces are monitored. -g starts the general interface statistics -d iface shows detailed statistics for the specified interface -s iface starts the TCP/UDP traffic monitor for the specified interface -z iface starts the packet size breakdown for the specified interface -l iface starts the LAN station monitor on the specified interface. If -l all is specified, all LAN interfaces are monitored. -t timeout The -t parameter, when used with one of the other parameters that specify a facility to start, tells IPTraf to run the indicated facility for only timeout minutes, after which the facility exits. The -t parameter is ignored in menu mode. If this parameter is not specified, the facility runs until the exit keystroke is pressed. -B Redirects all terminal output to the "bit bucket" /dev/null, closes standard input, and places the program in the background. This parameter can be used only with one of the -i, -g, -d, -s, -z, or -l parameters. See Background Operation in Chapter 9. -B is ignored in menu mode. -L filename Allows you to specify an alternate log file name when the any facility is directly started from the command line, whether in foreground or background mode. If specified in foreground mode, the log filename prompt is bypassed, even when logging is turned on in the Configure... menu. If this parameter is omitted in background mode, the default log filename is used. This parameter always turns on logging. If an absolute path is not specified, the log file will be created in the default log file directory -I interval Sets the logging interval (in minutes) when the -L parameter is used. This overrides the Log interval... setting in the Configure... menu. If omitted, the configured value is used. This parameter is ignored when the -L parameter is omitted and logging is disabled. The value specified here will affect all facilities except for the IP traffic monitor. -q Previously used to suppress the warning screen when IPTraf is run on kernels with IP masquerading. Since the masquerading code now processes packets in a way better suited to raw capture, this parameter is no longer needed and is retained only for compatibility. -f Forces IPTraf to clear all lock files and reset all instance counters to zero before running any facilities. IPTraf will then think it's the first instance of itself. The -f parameter overrides the existing locks and counters imposed by the IPTraf process and by the various facilities, causing this instance to think it is the first and that there are no other facilities running. Use this parameter with great caution. A common use for this parameter is to recover from abrupt or abnormal terminations which may leave stale locks and counters still lying around. The -f parameter may be used together with the others. iptraf -h displays a short help screen While the command-line options are case-sensitive, interactive keystroke at the IPTraf full-screen interface are not. Using the Menus Menu items with a trailing ellipsis (...) either pop up a submenu with further items, or require additional information before it can complete the task and return to the menu. Menu items without an ellipsis execute immediately. Use the Up and Down arrow keys on your keyboard to move the selection bar. Press Enter to execute the selected item. Alternatively, you can also directly press the highlighted letter of the item you want. This will immediately execute the option.
The IPTraf Main Menu
Exiting IPTraf You can exit IPTraf with the Exit command in the main menu. When started with one of the command-line options to directly start a statistical facility, pressing X or Q will exit the facility directly, without any confirmation. The -t command-line parameter will automatically exit the facility after the specified length of time without any confirmation as well. Daemon facilities started with the -B parameter will immediately terminate after being sent a USR2 signal. See background operation in chapter 9 for more information. Preparing to Use IPTraf This chapter provides information applicable to all of IPTraf's statistical monitors. Number Display Notations IPTraf initially returns exact counts of bytes and packets. However, as they grow larger, IPTraf begins displaying them in increasingly higher denominations. A number standing alone with no suffix represents an exact count. A number with a K following is a kilo (thousand) figure. An M, G, and T suffix represents mega (million), giga (billion), and tera (trillion) respectively. The following table shows examples. Numeric Display Notations 1024067exactly 1024067 1024Kapproximately 1024000 1024Mapproximately 1024000000 1024Gapproximately 1024000000000 1024Tapproximately 1024000000000000
These notations apply to both packet and byte counts. Instances and Logging Since version 2.4, IPTraf allows multiple instances of the facilities at the same time in different processes (for example, you can now run two or more IP Traffic Monitors at the same time). However only one can listen on a specific interface or all interfaces at once. The only exception is the general interface statistics, which is still restricted to only one instance at a time. Because of this relaxation, each instance now generates log files with unique names for instances, depending on either their instance or the interface they're listening on. If the Logging option is turned on (see the Configuration chapter), IPTraf will prompt you for a log file name while presenting a default. You may accept this default or change it. Press Enter to accept, or Ctrl+X to cancel. Canceling will turn logging off for that particular session. If you don't specify an absolute path, the log file will be placed in /var/log/iptraf.
The logfile prompt dialog
See the Logging section in the Configuration chapter for detailed information on logging. See also the documentation on each statistical facility for the default log file names. The default log file names will also be used if the -B parameter is used to run IPTraf in the background. You can override the defaults with the -L parameter. See Background Operation in Chapter 9. Screen Update Delays Older versions of IPTraf updated the screen as soon as a packet was received. However, screen update is one of the slowest operations the program performs. Since version 1.3, a configuration option has been available to control screen update speed. See the Screen update interval... configuration option under the Configuration chapter of this manual. Supported Network Interfaces IPTraf currently supports the following network interface types and names. lo The loopback interface. Every machine has one, and has an IP address of 127.0.0.1. lo is also indicated if data is detected on the dummyn interface(s). ethn An Ethernet interface. n starts from 0. Therefore, eth0 refers to the first Ethernet interface, eth1 to the second, and so on. Most machines only have one. fddin An FDDI interface. n starts from 0. trn A Token Ring interface, where n starts from 0. pppn A PPP interface. n starts from 0. slin A SLIP interface. n starts from 0. plipn PLIP interfaces. These are point-to-point IP connections using the PC parallel port. ipsecn This refers to Free s/WAN (and possibly other) logical VPN interfaces. sbnin SBNI long-range modem interfaces dvbn, sm200, sm300 DVB satellite-receive interfaces wlann, wvlann Wireless LAN interfaces tunn general logical tunnel interfaces brgn general logical bridge interfaces hdlcn Frame Relay base (FRAD) interfaces (non-PVC) pvcn Frame Relay Permanent Virtual Circuit interfaces Your system's network interfaces must be named according to the schemes specified above. The IP Traffic Monitor Executing the first menu item or specifying -i to the iptraf command takes you to the IP traffic monitor. The traffic monitor is a real-time monitoring system that intercepts all packets on all detected network interfaces, decodes the IP information on all IP packets and displays the appropriate information, most notably the source and destination addresses. It also determines the encapsulated protocol within the IP packet, and displays some important information about that as well. There are two windows in the traffic monitor, both of which can be scrolled with the Up and Down cursor keys. Just press W to move the Active indicator to the window you want to control.
The IP traffic monitor
The Upper Window The upper window of the traffic monitor displays the currently detected TCP connections. Information about TCP packets are displayed here. The window contains these pieces of information: Source address and port Packet count Byte count Source MAC address Packet Size Window Size TCP flag statuses Interface Note Previous versions of IPTraf showed both the source and destination addresses on each line. IPTraf 2 and higher show only the source host:port combination to save on screen real estate. TCP connection endpoints are still indicated with the green brackets (on color terminals) along the left edge of the screen. The Up and Down cursor keys move an indicator bar between entries in the TCP monitor, scrolling the window if necessary. The PgUp and PgDn keys display the previous and next screenfuls of entries respectively. The IP traffic monitor computes the data flow rate of the currently highlighted TCP flow and displays it on the lower-right corner of the screen. The flow rate is in kilobits or kilobytes per second depending on the Activity mode switch in the Configure... menu. Because this monitoring system relies solely on packet information, it does not determine which endpoint initiated the connection. In other words, it does not know which endpoints are the client and server. This is necessary because it can operate in promiscuous mode, and as such cannot determine the socket statuses for other machines on the LAN. However, a little knowledge of the well-known TCP port numbers can give a good idea about which address is that of the server. The system therefore displays two entries for each connection, one for each direction of the TCP connection. To make it easier to determine the direction pairs of each connection, a bracket is used to "join" both together. This bracket appears at the leftmost part of each entry. Just because a host entry appears at the upper end of a connection bracket doesn't mean it was the initiator of the connection. Each entry in the window contains these fields: Source address and port The source address and port indicator is in address:port format. This indicates the source machine and TCP port on that machine from which this data is coming. The destination is the host:port at the other end of the bracket. Packet count The number of packets received for this direction of the TCP connection Byte count The number of bytes received for this direction of the TCP connection. These bytes include total IP and TCP header information, in addition to the actual data. Data link header (e.g. Ethernet and FDDI) data are not included. Source MAC address The address of the host on your local LAN that delivered this packet. This can be viewed by pressing M once if Source MAC addrs in traffic monitor is enabled in the Configure... menu. Packet Size The size of the most recently received packet. This item is visible if you press M for more TCP information. This is the size of the IP datagram only, not including the data link header. Window Size The advertised window size of the most recently received packet. This item is visible if you press M for more TCP information. Flag statuses The flags of the most recently received packet. S SYN. A synchronization is taking place in preparation for connection establishment. If only an S is present (S---) the source is trying to initiate a connection. If an A is also present (S-A-), this is an acknowledgment of a previous connection request, and is responding. A ACK. This is an acknowledgment of a previously received packet P PSH. A request to push all data to the top of the receiving queue U URG. This packet contains urgent data RESET RST. The source machine indicated in this direction reset the entire connection. The direction entries for reset connections become available for new connections. DONE The connection is done sending data in this direction, and has sent a FIN (finished) packet, but has not yet been acknowledged by the other host. CLOSED The FIN has been acknowledged by the other host. When both directions of a connection are marked CLOSED, the entries they occupy become available for new connection entries. - The flag is not set Some other pieces of information can be viewed as well. The M key displays more TCP information. Pressing M once displays the MAC addresses of the LAN hosts that delivered the packets (if the Source MAC addrs in traffic monitor option is enabled in the Configure... menu). N/A is displayed if no packets have been received from the source yet, or if the interface doesn't support MAC addresses (such as PPP interfaces). If the Source MAC addrs in traffic monitor option is not enabled, pressing M simply toggles between the counts and the packet and window sizes. By default, only IP addresses are displayed, but if you have access to a name server or host table, you may enable reverse lookup for the IP addresses. Just enable reverse lookup in the Configure... menu. The rvnamed Process The IP traffic monitor starts a daemon called rvnamed to help speed up reverse lookups without sacrificing too much keyboard control and accuracy of the counts. While reverse lookup is being conducted in the background, IP addresses will be used until the resolution is complete. If for some reason rvnamed cannot start (probably due to improper installation or lack of memory), and you are on the Internet, and you enable reverse lookup, your keyboard control can become very slow. This is because the standard lookup functions do not return until they have completed their tasks, and it can take several seconds for a name resolution in the foreground to complete. rvnamed will spawn up to 200 children to process reverse DNS queries. Tip If you notice unusual SYN activity (too many initial (S---) but frozen SYN entries, or rapidly increasing initial SYN packets for a single connection), you may be under a SYN flooding attack or TCP port scan. Apply appropriate measures, or the targeted machines may begin denying network services. Entries not updated within a user-configurable amount of time may get replaced with new connections. The default time is 15 minutes. This is regardless of whether the connection is closed or not. (Some unclosed connections may be due to extremely slow links or crashes at either end of the connection.) This figure can be changed at the Configure... menu. Some early entries may have a > symbol in front of its packet count. This means the connection was already established when the monitor started. In other words, the figures indicated do not reflect the counts since the start of the TCP connection, but rather, since the start of the traffic monitor. Eventually, these > entries will close (or time out) and disappear. TCP entries without the > were initiated after the traffic monitor started, and the counts indicate the totals of the connection itself. Just consider entries with > partial. Some > entries may go idle if the traffic monitor was started when these connections were already half-closed (FIN sent by one host, but data still being sent by the other). This is because the traffic monitor cannot determine if a connection was already half-closed when it started. These entries will eventually time out. (To minimize these entries, an entry is not added by the monitor until a packet with data or a SYN packet is received.) Direction entries also become available for reuse if an ICMP Destination Unreachable message is received for the connection. The lower part of the screen contains a summary line showing the IP, TCP, UDP, ICMP, and non-IP byte counts since the start of the monitor. The IP, TCP, UDP, and ICMP counts include only the IP datagram header and data, not the data-link headers. The non-IP count includes the data-link headers. Technical note: IP Forwarding and Masquerading Previous versions of IPTraf issued a warning if the kernel had IP masquerading enabled due to the way the kernel masqueraded and translated the IP addresses. The new kernels no longer do it as before and IPTraf now gives output properly on masquerading machines. The -q parameter is no longer required to suppress the warning screen. On forwarding (non-masquerading) machines packets and TCP connections simply appear twice, one each for the incoming and outgoing interfaces if all interafaces are being monitored. On masquerading machines, packets and connections from the internal network to the external network also appear twice, one for the internal and external interface. Packets coming from the internal network will be indicated as coming from the internal IP address that sourced them, and also as coming from the IP address of the external interface on your masquerading machine. In much the same way, packets coming in from the external network will look like they're destined for the external interface's IP address, and again as destined for the final host on the internal network. Closed/Idle/Timed Out Connections A TCP connection entry that closes, gets reset, or stays idle too long normally gets replaced with new connections. However, if there are too many of these, active connections may become interspersed among closed, reset, or idle entries. IPTraf can be set to automatically remove all closed, reset, and idle entries with the TCP closed/idle persistence... configuration option. You can also press the F key to immediately clear them at any time. Note The TCP timeout... option only tells IPTraf how long it should take before a connection should be considered idle and open to replacement by new connections. This does not determine how long it remains on-screen. The TCP closed/idle persistence... parameter flushes entries that have been idle for the number of minutes defined by the TCP timeout... option. Sorting TCP Entries The TCP connection entries can be sorted by pressing the S key, then by selecting a sort criterion. Pressing S will display a box showing the available sort criteria. Press P to sort by packet count, B to sort by byte count. Pressing any other key cancels the sort. The sort operation compares the larger values in each connection entry pair and sorts the counts in descending order. Over time, the entries will go out of order as counts proceed at varying rates. Sorting is not done automatically so as not to degrade performance and accuracy.
The IP traffic monitor sort criteria
Lower Window The lower window displays information about the other types of traffic on your network. The following protocols are detected internally: User Datagram Protocol (UDP) Internet Control Message Protocol (ICMP) Open Shortest-Path First (OSPF) Interior Gateway Routing Protocol (IGRP) Interior Gateway Protocol (IGP) Internet Group Management Protocol (IGMP) General Routing Encapsulation (GRE) Layer 2 Tunneling Protocol (L2TP) IPSec AH and ESP protocols (IPSec AH and IPSec ESP) Address Resolution Protocol (ARP) Reverse Address Resolution Protocol (RARP) Other IP protocols are looked up from the /etc/services file. If /etc/services doesn't contain information about that protocol, the protocol number is indicated. Non-IP packets are indicated as Non-IP in the lower window. Note The source and destination addresses for ARP and RARP entries are MAC addresses. Strictly speaking, ARP and RARP packets aren't IP packets, since they are not encapsulated in an IP datagram. They're just indicated because they are integral to proper IP operation on LANs. For all packets in the lower window, only the first IP fragment is indicated (since that contains the header of the IP-encapsulated protocol) but with no further information from the encapsulated protocol. UDP packets are also displayed in address:port format while ICMP entries also contain the ICMP message type. For easier location, each type of protocol is color-coded (only on color terminals such as the Linux console). UDPRed on White ICMPYellow on Blue OSPFBlack on Cyan IGRPBright white on Cyan IGPRed on Cyan IGMPBright green on Blue GREBlue on white ARPBright white on Red RARPBright white on Red Other IPYellow on red Non-IPYellow on Red The lower window can hold up to 512 entries. You can scroll the lower window by using the W key to move the Active indicator to it, and by using the Up and Down cursor keys. The lower window automatically scrolls every time a new entry is added, and either the first entry or last entry is visible. Upon reaching 512 entries, old entries are thrown out as new entries are added. Some entries may be too long to completely fit in a screen line. You can use the Left and Right cursor keys to vertically scroll the lower window when it is marked Active. If your terminal can be resized (e.g. xterm), you may do so before starting IPTraf. Entries for packets received on LAN interfaces also include the source MAC address of the LAN host which delivered it. This behavior is enabled by turning on the Source MAC addrs in traffic monitor toggle in the Configure... menu. Entry Details In general, the entries in the lower window indicate the protocol, the IP datagram size (full frame size for non-IP, including ARP and RARP), the source address, the destination address, and the network interface the packet was detected on. However, some protocols have a little more information. ICMP ICMP entries are displayed in this format: ICMP type [(subtype)] (size bytes) from source to destination [(src HWaddr srcMACaddress)] on interface where type could be any of the following: echo req, echo rply ICMP echo request and reply. Usually used by the ping program and other network monitoring and diagnostic program. dest unrch ICMP destination unreachable. Something failed to reach its target. The dest unreach type is supplemented with a further indicator of the problem. Destination unreachable messages for TCP traffic causes the corresponding TCP entry in the upper window to be made available for reuse by new connections. redirct ICMP redirect. Usually generated by a router to tell a host that a better gateway is available. src qnch The ICMP source quench is used to stop a host from transmitting. It's a flow control mechanism for IP. time excd Indicates a packet's time-to-live value expired before it got to its destination. Mostly happens if a destination is too far away. Also used by the traceroute program. router adv ICMP router advertisement router sol ICMP router solicitation timestmp req ICMP timestamp request timestmp rep ICMP timestamp reply info req ICMP information request info rep ICMP information reply addr mask req ICMP address mask request addr mask rep ICMP address mask reply param prob ICMP parameter problem bad/unknown An unrecognized ICMP packet was received, or the packet is corrupted. The destination unreachable message also includes information on the type of error encountered. Here are the destination unreachable codes: ntwk network unreachable host host unreachable proto protocol unreachable port port unreachable pkt fltrd packet filtered (normally by an access rule on a router or firewall) DF set the packet has to be fragmented somewhere, but its don't fragment (DF) bit is set. src rte fail source route failed src isltd source isolated (obsolete) net comm denied network communication denied host comm denied host communication denied net unrch for TOS network unreachable for specified IP type-of-service host unrch for TOS host unreachable for specified IP type-of-service prec violtn precedence violation prec cutoff precedence cutoff dest net unkn destination network unknown dest host unkn destination network unknown For more information on ICMP, see RFC 792. OSPF OSPF messages also include a little more information. The format of an OSPF message in the window is: OSPF type (a=area r=router) (sizebytes) from source to destination [(src HWaddr srcMACaddress)] on interface The type can be one of the following: hlo OSPF hello. Hello messages establish OSPF communications and keep routers informed of each other's presence. DB desc OSPF Database Description LSR OSPF Link State Request LSU OSPF Link State Update. Messages indicating the states of the OSPF network links LSA OSPF Link State Acknowledgment The entries in parentheses: a=area The area number of the OSPF message r=router The IP address of the router that generated the message. It is not necessarily the same as the source address of the encapsulating IP packet. Many times, the destination addresses for OSPF packets are class D multicast addresses in standard dotted decimal notation or (if reverse lookup is enabled), hosts under the MCAST.NET domain. Such multicast addresses are defined as follows: 224.0.0.5 (OSPF-ALL.MCAST.NET) OSPF all routers 224.0.0.6 (OSPF-DSIG.MCAST.NET) OSPF all designated routers See RFC 1247 for details on the OSPF protocol. Additional Information When started from the main menu and logging is enabled, the IP traffic monitor prompts you for a log file name. The default name is ip_traffic-n.log (where n is what instance of the traffic monitor this is (1, 2, 3, and so on). (e.g. if this is the first instance, the default file name will be ip_traffic-1.log.) When started with the -i parameter, the log filename can be specified with the -L parameter. See the Command-line Parameters section above for more information. On busy networks, the display may become cluttered with traffic you're not interested in. To control the traffic monitor's output, you can apply a filter. See Chapter 7, Filters for more information on IPTraf's filters. At any time, you can press X or Q to return to the main menu (or back to the shell if the monitor was started with iptraf -i). Network Interface Statistics There are two network interface statistics facilities: the general interface statistics, which displays a statistical summary of all attached interfaces, and the detailed interface statistics, which shows more statistical and load information about a single selected interface. General Interface Statistics The second menu option displays a list of attached network interfaces, and some general packet counts. Specifically, it displays counts of IP, non-IP, and bad IP packets (packets with IP checksum errors). It also includes an activity indicator, which shows the number of kilobits and packets the interface sees per second. All figures are for incoming and outgoing packets. (Again, considering promiscuous mode for LAN interfaces, which simply causes the machine to intercept all packets). This is useful for general monitoring of all attached interfaces. If byte counts and additional information are needed for a specific interface, the Detailed interface statistics option is also available. The activity indicators can be toggled between kbits/s and kbytes/s with the Activity mode configuration option. The general statistics window will dynamically add new entries as packets from newly-created interfaces (e.g. new PPP interfaces) are intercepted. Long lists can be scrolled with the Up, Down, PgUp, and PgDn keys. This monitor is affected by IPTraf's filters as described in Chapter 7. Copies of the statistics are written to the log file iface_stats_general.log at regular intervals if logging is enabled. See the Logging option int the Configuration chapter. This facility can be started directly from the command line with the -g option to the iptraf command. When started from the command line, the log filename and log interval can be specified with the -L and -I parameters respectively. See the Command-line Parameters section above for more information.
The general interface statistics screen
You can press X or Q to return to the main menu. Detailed Interface Statistics The third menu option displays packet statistics for any selected interface. It provides basically the same information as the General interface statistics option, with additional details. This facility provides the following information: Total packet and byte counts IP packet and byte counts TCP packet and byte counts UDP packet and byte count ICMP packet and byte counts Other IP-type packet and byte counts Non-IP packet and byte counts Checksum error count Interface activity Broadcast packet and byte counts All IP byte counts (IP, TCP, UDP, ICMP, other IP) include IP header data and payload. The data link header is not included. The full frame length (including data-link header) is included in the non-IP and Total byte count. All data-link headers are also included in the Total byte counts.
The detailed interface statistics screen
The upper portion of the screen contains the packet and byte counts for all IP and non-IP packets intercepted on the interface. The lower portion contains the total, incoming, and outgoing interface data rates. This facility also displays incoming and outgoing counts and data rates. The packet size breakdown in versions prior to 2.0.0 has been moved to its own facility under Statistical breakdowns.../By packet size as described in Chapter 5. An outgoing packet is one that exits your interface, regardless of whether it originated from your machine or came from another machine and was routed through yours. An incoming packet is one that enters your interface, either addressed to you directly, broadcast, multicast, or captured promiscuously. The rate indicators can be set to display kbits/s or kbytes/s with the Activity mode configuration option. Note Buffering and some other factors may affect the data rates, notably the outgoing rate, causing it to reflect a higher figure than the actual rate at which the interface is sending. The figures are logged at regular intervals if logging is enabled. The default log file name at the prompt is iface_stats_detailed-iface.log where iface is the selected interface for this session (for example, iface_stats_detailed-eth0.log). If you wish to start this facility directly from the command line, you can specify the -d parameter and an interface to monitor. For example, iptraf -d eth0 starts the statistics for eth0. The interface must be specified, or IPTraf will not start the facility. When started from the command line, the log filename and log interval can be specified with the -L and -I parameters respectively. See the Command-line Parameters section above for more information. Note In both the general and detailed statistics screens, as well as in the IP traffic monitor, the packet counts are for actual network packets (layer 2), not the logical IP packets (layer 3) that may be reconstructed after fragmentation. That means, if a packet was fragmented into four pieces, and these four fragments pass over your interface, the packet counts will indicate four separate packets. The figure for the IP checksum errors is a packet count only, because the corrupted IP header cannot be relied upon to give a correct IP packet length value. This facility's output is also affected by IPTraf's filters. See Chapter 7 for more information on filters. Pressing X or Q takes you back to the main menu (if this facility was started with the command-line option, X or Q drops you back to the shell). Statistical Breakdowns Statistical breakdowns contain two facilities that break down traffic counts by either packet size or TCP/UDP port. Packet Sizes The packet size breakdown facility used to be incorporated into the detailed interface statistics. It has since been moved to its own facility. It is entered by selecting Statistical Breakdowns/By packet size. The packet size breakdown takes the interface's Maximum Transmission Unit (MTU) size and divides it into 20 brackets, each bracket containing a range of sizes. As a packet is captured, its size is determined and the appropriate bracket is incremented. This facility provides an idea as to the packet sizes passing over your network, and can aid in network (re)design decisions.
The packet size statistical breakdown
If logging is enabled, copies of the statistics are written at regular intervals to a log file. The default log file name is packet_size-iface.log where iface is the selected interface for this session (for example, packet_size-eth0.log). IPTraf's filters do not affect this facility. The packet size breakdown can also be invoked straight from the command line by specifying the -z iface parameter. The interface parameter is required. For example, this command runs the facility on interface eth0. iptraf -z eth0 When started from the command line, the log filename and log interval can be specified with the -L and -I parameters respectively. See the Command-line Parameters section above for more information. To exit, press X or Ctrl+X. TCP and UDP Traffic Statistics IPTraf also includes a facility that generates statistics on TCP and UDP traffic. This facility displays counts of all TCP and UDP packets with source or destination ports numbered less than 1024. Ports 1 to 1023 are reserved for the TCP/IP application protocols (well-known ports).
The TCP/UDP service monitor
The statistics window indicates the protocol (TCP or UDP), the port number, the total packets and bytes counted for this particular protocol/port combination, the packets and bytes destined for that protocol and port, and the packets and bytes coming from that protocol and port. Byte counts include the IP header and payload only. The data link header is not included. The protocol/port indicators are color-coded for easier identification on color terminals. TCP indicators are in yellow, UDP in bright green. Some network applications or protocols may use port numbers higher than 1023. Examples of these include application proxy servers (HTTP proxy servers typically use values like 8000, 8080, 8888, and the like), and IRC (IRC servers commonly accept connections on ports 6660 to 6669). These ports are by default not included in the counts. If you do want to include a higher-numbered port in the statistics, you can add them yourself from the Configure.../Additional ports... menu item. See the section below. If logging is enabled, The statistics are also written to a log file (the default name is tcp_udp_services-iface.log, where iface is the selected interface (for example, tcp_udp_services-eth0.log). IPTraf computes the total, incoming, outgoing, and data rates of the protocol currently indicated by the facility's highlight bar. The data rates are indicated at the bottom of the screen. If logging is enabled, the average data rates since the start of the facility are placed in the log file. The Up and Down cursor keys move the highlight bar. Pressing X or Ctrl+X exits and returns to the main menu (or the shell if it was started from the command line). Sorting TCP/UDP Entries Pressing the S key brings up a window which allows you to select the field by which the entries will be sorted. You can press R to sort by port, P to sort by total packets, B to sort by total bytes, T to sort by incoming packets (packets to), O to sort by incoming bytes (bytes to), F to sort by outgoing packets (packets from) and M to sort by outgoing bytes (bytes from). Pressing any other key cancels the sort. Port numbers are sorted in ascending order (least first) but statistics are sorted in descending order (largest counts first). As with the IP traffic monitor, sorting is performed only with this sequence. Automatic sorting is not performed so as not to affect performance.
The TCP/UDP monitor's sort criteria
Additional Information IPTraf's filters affect the output of this facility. See Chapter 7, Filters for more information about filters. If you wish to start this facility from the command line, you can use the -s option followed by an interface to monitor. For example, iptraf -s eth0 brings up this module for traffic on eth0. The interface must be specified, or IPTraf will drop back to the shell. When started from the command line, the log filename and log interval can be specified with the -L and -I parameters respectively. See the Command-line Parameters section above for more information. LAN Station Statistics The LAN station monitor (Ethernet station monitor on versions prior to 1.3.0) discovers MAC addresses and displays statistics on the number of incoming, and outgoing packets. It also includes figures for incoming and outgoing kilobits per second for each discovered station. The entry above each line of statistics is the station's LAN type (Ethernet, PLIP, Token Ring, or FDDI) and the hardware MAC address. Each statistics line consists of the following information: Total packets incoming IP packets incoming Total bytes incoming Incoming rate Total packets outgoing IP packets outgoing Total bytes outgoing Outgoing rate The byte counts include the data link header. The activity indicators can be set to display kbits/s or kbytes/s with the Activity mode configuration option. This facility works only for Ethernet, PLIP, Token Ring, and FDDI frames. Loopback. ISDN, and SLIP/PPP networks are not monitored here.
The LAN station monitor
Copies of the statistics are written to a log file at regular intervals if logging is enabled. The default log file name is lan_statistics-n.log, where n is the instance number of this facility (for example, if this is the first instance, the generated default log file name is lan_statistics-1.log). Sorting the LAN Station Monitor Entries Press S to sort the entries. A box will pop up and display the keys you can press to select the field by which the entries will be sorted. Press P to sort by total incoming packets, I to sort by incoming IP packets, B to sort by total incoming bytes, K to sort by total outgoing packets, O to sort by outgoing IP packets, and Y to sort by total outgoing bytes. Pressing any other key cancels the sort.
The LAN station monitor's sort criteria When started from the command line, the log filename and log interval can be specified with the -L and -I parameters respectively. See the Command-line Parameters section above for more information. Additional Information The window can be scrolled with the Up and Down cursor keys. Press X or Q to return to the main menu (or the shell if this facility was started with the -l command-line option). The output of this facility is affected by any applied IPTraf filter. Filters Filters are used to control the information displayed by all facilities. You may want to view statistics only on particular traffic so you must restrict the information displayed. The filters also apply to logging activity. The IPTraf filter management system is accessible through the Filters... submenu.
The Filters submenu
IP Filters The Filters/IP... menu option allows you to define a set of rules that determine what IP traffic to pass to the monitors. Selecting this option pops up another menu with the tasks used to define and apply custom IP filters.
The IP filter menu
Defining a New Filter A freshly installed program will have no filters defined, so before anything else, you will have to define a filter. You can do this by selecting the Define new filter... option. Selecting this option displays a box asking you to enter a short description of the filter you are going to define. Just enter any text that clearly identifies the nature of the filter.
The IP filter name dialog
Press Enter when you're done with that box. As an alternative, you can also press Ctrl+X to cancel the operation. The Filter Rule Selection Screen After you enter the filter's description, you will be taken to a blank rule selection box. At this screen you manage the various rules you define for this filter. You can opt to insert, append, edit, or delete rules.
The filter rule selection screen. Selecting an entry displays that set for editing
Any rules defined will appear here. You will see the source and destination addresses, masks and ports (long addresses and masks may be truncated) and whether this rule includes or excludes matching packets. Between the source and destination parameters is an arrow that indicates whether the rule matches packets (single-headed) only exactly or whether it matches packets flowing in the opposite direction (double-headed). At this screen, press I to insert at the current position of the selection bar, A to append a rule to the end of the list, Enter to edit the highlighted rule and D to delete the selected rule. With an empty list, A or I can be used to add the first rule. To add the first rule, press A or I. You will then be presented with a dialog box that allows you to enter the rule's parameters. Entering Filter Rules You can enter addresses of individual hosts, networks, or a catch-all address. The nature of the address will be determined by the wildcard mask. You'll notice two sets of fields, marked Source and Destination. You fill these out with the information about your source and targets. Fill out the host name or IP address of the hosts or networks in the first field marked Host name/IP Address. Enter it in standard dotted-decimal notation. When done, press Tab to move to the Wildcard mask field. The wildcard mask is similar but not exactly identical to the standard IP subnet mask. The wildcard mask is used to determine which bits to ignore when processing the filter. In most cases, it will work very closely like a subnet mask. Place ones (1) under the bits you want the filter to recognize, and keep zeros (0) under the bits you want the filter to ignore. For example: To recognize the host 207.0.115.44 IP address207.0.115.44 Wildcard mask255.255.255.255 To recognize all hosts belonging to network 202.47.132.x IP address202.47.132.0 Wildcard mask255.255.255.0 To recognize all hosts with any address: IP address0.0.0.0 Wildcard mask0.0.0.0 The IP address/wildcard mask mechanism of the display filter doesn't recognize IP address class. It uses a simple bit- pattern matching algorithm. The wildcard mask also does not have to end on a byte boundary; you may mask right into a byte itself. For example, 255.255.255.224 masks 27 bits (255 is 11111111, 224 is 11100000 in binary). IPTraf also accepts host names in place of the IP addresses. IPTraf will resolve the host name when the filter is loaded. When the filter is interpreted, the wildcard mask will also be applied. This can be useful in cases where a single host name may resolve to several IP addresses. Tip See the Linux Network Administrator's Guide if you need more information on IP addresses and subnet masking. Tip IPTraf allows you to specify the wildcard mask in Classless Interdomain Routing (CIDR) format. This format allows you to specify the number of 1-bits that mask the address. CIDR notation is the form address/bits where the address is the IP address or host name and bits is the number of 1-bits in the mask. For example, if you want to mask 10.1.1.0 with 255.255.255.0, note that 255.255.255.0 has 24 1-bits, so instead of specifying 255.255.255.0 in the wildcard mask field, you can just enter 10.1.1.0/24 in the address field. IPTraf will translate the mask bits into an appropriate wildcard mask and fill in the mask field the next time you edit the filter rule. If you specify the mask in CIDR notation, leave the wildcard mask fields blank. If you fill them up, the wildcard mask fields will take precedence. The Port fields should contain a port number or range of any TCP or UDP service you may be interested in. If you want to match only a single port number, fill in the first field, while leaving the second blank or set to zero. Fill in the second field if you want to match a range of ports (e.g. 80 to 90). Leave the first field blank or set to zero to let the filter ignore the ports altogether. You will most likely be interested in target ports rather than source ports (which are usually unpredictable anyway, perhaps with the exception of FTP data). Non-TCP and non-UDP packets are not affected by these fields, and these are used only when filtering TCP or UDP packets. Fill out the second set of fields with the parameters of the opposite end of the connection. Tip Any address or mask fields left blank default to 0.0.0.0 while blank Port fields default to 0. This makes it easy to define filter rules if you're interested only in either the source or destination, but not the other. For example, you may be interested in traffic originating from network 61.9.88.0, in which case you just enter the source address, mask and port in the Source fields, while leaving the Destination fields blank. The next fields let you specify which IP-type protocols you want matched by this filter rule. Any packet whose protocol's corresponding field is marked with a Y is matched against the filter's defined IP addresses and ports, otherwise they don't pass through this filter rule. If you want to evaluate all IP packets just mark with Y the All IP field. For example, if you want to see only all TCP traffic, mark the TCP field with Y. The long field marked Additional protocols allows you to specify other protocols by their IANA number. (You can view the common IP protocol number in the /etc/protocols file). You can specify a list of protocol numbers or ranges separated by commas, Ranges have the beginning and ending protocol numbers separated with a hyphen. For example, to see the RSVP (46), IP mobile (55), and protocols (101 to 104), you use an entry that looks like this: 46, 55, 101-104 It's certainly possible to specify any of the protocols listed above in this field. Entering 1-255 is functionally identical to marking All IP with a Y. The next field is marked Include/Exclude. This field allows you to decide whether to include or filter out matching packets. Setting this field to I causes the filter to pass matching packets, while setting it to E causes the filter to drop them. This field is set to I by default. The last field in the dialog is labeled Match opposite. When set to Y, the filter will match packets flowing in the opposite direction. Previous versions of IPTraf used to match TCP packets flowing in either direction, so the source and destination address/mask/port combinations were actually interchangeable. Starting with IPTraf 3.0, when filters extended to more than just the IP traffic monitor, this behavior is no longer the default throughout IPTraf except in the IP traffic monitor's TCP window. Note For TCP packets, this field is used in all facilities except the IP traffic monitor. Because the IP traffic monitor must capture TCP packets in both directions to properly determine a closed connection, the filter automatically matches packets in the opposite direction, regardless of this field's setting. However iin all other facilities, automatic matching of the reverse packets is not performed unless you set this field to Y. Filters for UDP and other IP protocols do not automatically match packets in the opposite direction unless you set the field to Y, even in the IP traffic monitor. Press Enter to accept all parameters when done. The parameters will be accepted and you'll be taken back to the rule selection box. You can then add more rules by pressing A or you can insert new rules at any point by pressing I. Should you make a mistake, you can press Enter to edit the selected filter. You may enter as many sets of parameters as you wish. Press Ctrl+X when done. Note Because of the major changes in the filtering system since IPTraf 2.7, old filters will no longer work and will have to be redefined.
The IP filter parameters dialog
Examples To see all traffic to/from host 202.47.132.1 from/to 207.0.115.44, regardless of TCP port Host name/IP Address202.47.132.2207.0.115.44 Wildcard mask255.255.255.255255.255.255.255 Port00 ProtocolsTCP: Y Include/ExcludeI Match oppositeY To see all traffic from host 207.0.115.44 to all hosts on network 202.47.132.x Host name/IP Address207.0.115.44202.47.132.0 Wildcard mask255.255.255.255255.255.255.0 Port00 ProtocolsAll IP: Y Include/ExcludeI Match oppositeN To see all Web traffic (to and from port 80) regardless of source or destination Host name/IP Address0.0.0.00.0.0.0 Wildcard mask0.0.0.00.0.0.0 Port800 ProtocolsTCP: Y Include/ExcludeI Match oppositeY To see all IRC traffic from port 6666 to 6669 Host name/IP Address0.0.0.00.0.0.0 Wildcard mask0.0.0.00.0.0.0 Port06666 to 6669 ProtocolsTCP: Y Include/ExcludeI Match oppositeY To see all DNS traffic, (TCP and UDP, destination port 53) regardless of source or destination Host name/IP Address0.0.0.00.0.0.0 Wildcard mask0.0.0.00.0.0.0 Port053 ProtocolsTCP: Y UDP: Y Include/ExcludeI Match oppositeY To see all mail (SMTP) traffic to a single host (202.47.132.2) from anywhere Host name/IP Address0.0.0.0202.47.132.2 Wildcard mask0.0.0.0255.255.255.255 Port025 ProtocolsTCP: Y Include/ExcludeI Match oppositeN To see traffic from from/to host sunsite.unc.edu to/from cebu.mozcom.com Host name/IP Addresssunsite.unc.educebu.mozcom.com Wildcard mask255.255.255.255255.255.255.255 Port00 ProtocolsAll IP: Y Include/ExcludeI Match oppositeY To omit display of traffic to/from 140.66.5.x from/to anywhere Host name/IP Address140.66.5.00.0.0.0 Wildcard mask255.255.255.00.0.0.0 Port00 ProtocolsAll IP: Y Include/ExcludeE Match oppositeY You can enter as many parameters as you wish. All of them will be interpreted until the first match is found. Excluding Certain Sites Filters follow an implicit "no-match" policy, that is, only packets matching defined rules will be matched, others will be filtered out. This is similar to the access-list policy "whatever is not explicitly permitted is denied". If you want to show all traffic to/from everywhere, except certain places, you can specify the sites you wish to exclude, mark them with E in the Include/Exclude field, and define a general catch-all entry with source address 0.0.0.0, mask 0.0.0.0, port 0, and destination 0.0.0.0, mask 0.0.0.0, port 0, tagged with an I in the Include/Exclude field as the last entry. For example: To see all traffic except all SMTP (both directions), Web (both directions), and traffic (only) from 207.0.115.44 Host name/IP address0.0.0.00.0.0.0 Wildcard mask0.0.0.00.0.0.0 Port250 ProtocolsTCP: Y Include/ExcludeE Match oppositeY Host name/IP address0.0.0.0 0.0.0.0 Wildcard mask0.0.0.00.0.0.0 Port800 ProtocolsTCP: Y Include/ExcludeE Match oppositeY Host name/IP address207.0.115.440.0.0.0 Wildcard mask255.255.255.2550.0.0.0 Port00 ProtocolsAll IP: Y Include/ExcludeE Match oppositeN Host name/IP address0.0.0.00.0.0.0 Wildcard mask0.0.0.00.0.0.0 Port00 ProtocolsAll IP: Y Include/ExcludeI Match oppositeN Tip To filter out all TCP, define a filter with a single entry, with a source of 0.0.0.0 mask 0.0.0.0 port 0, and a destination of 0.0.0.0 mask 0.0.0.0 port 0, with the Include/Exclude field marked E (exclude). Then apply this filter. Applying a Filter The above steps only add the filter to a defined list. To actually apply the filter, you must select Apply filter... from the menu. You will be presented with a list of filters you already defined. Select the one you want to apply, and press Enter. The applied filter stays in effect over exits and restarts of the IPTraf program until it is detached. Editing a Defined Filter Select Edit filter... to modify an existing filter. Once you select this option, you will be presented with the list of defined filters. Select the filter you want to edit by moving the selection bar and press Enter. Edit the description if you wish. Pressing Ctrl+X at this point will abort the operation, and the filter will remain unmodified. Press Enter to accept any changes to the filter description. After pressing Enter, you will see the filter's rules. To edit an existing filter rule, move the selection bar to the desired entry and press Enter. A prefilled dialog box will appear. Edit its contents as desired. Press Enter to accept the changes or Ctrl+X to discard. You can add a new filter rule by pressing I to insert at the selection bar's current position. When you press I, you will be presented with a dialog box asking you to enter the new rule data. Pressing A results in a similar operation, except the rule will be appended as the last entry in the rule list. Pressing D deletes the currently pointed entry. Press X or Ctrl+X to end the edit and save the changes. Note If you're editing the currently applied filter, you will need to re-apply the filter for the changes to take effect. Note Be aware that the filter processes the rules in order. In other words, if a packet matches more than one rule, only the first matching rule is followed. Deleting a Defined Filter Select Delete filter... from the menu to remove a filter from the list. Just move the selection bar to the filter you want to delete, and press Enter. Detaching a Filter The Detach filter option deactivates the filter currently in use. Selecting this option causes all TCP traffic to be passed to the monitors. When you're done with the menu, just select the Exit menu option. ARP, RARP, and other Non-IP Packet Filters The Non-IP filter option toggles the display and logging of all non-IP packets, except ARP and RARP, which are toggled separately. Configuring IPTraf IPTraf can be easily configured with the Configure... item in the main menu. The configuration is stored in the /var/local/iptraf/iptraf.cfg file. If the file is not found, IPTraf uses the default settings. Any changes to the configuration immediately get stored in the configuration file.
The IPTraf configuration menu
Toggles Reverse DNS Lookups Activating reverse lookup causes IPTraf to find out the name of the hosts with the addresses in the IP packets. When this option is enabled, IPTraf's IP traffic monitor starts the rvnamed DNS lookup server to help resolve IP addresses in the background while allowing IPTraf to continue capturing packets. This option is off by default. TCP/UDP Service Names This option, when on, causes IPTraf to display the TCP/UDP service names (smtp, www, pop3, etc.) instead of their numeric ports (25, 80, 110, etc). The number-to-name mappings will depend on the systems services database file (usually /etc/services). Should there be no corresponding service name for the port number, the numeric form will still be displayed. This setting is off by default. Note Reverse lookup and service name lookup take some time and may impact performance and increase the chances of dropped packets. Performance and results are best (albeit more cryptic) with both these settings off. Force promiscuous If this option is enabled, your LAN interfaces will capture all packets on your LAN. Using this option enables you to see all TCP connections and packets passing your LAN segment, even if they're not from or for your machine. When this option is active in the statistics windows, the Activity indicators will show a good estimate of the load on your LAN segment. When this option is disabled, you'll only receive information about packets coming from and entering your machine. The setting of this option affects all LAN ( Ethernet, FDDI, some Token Ring) interfaces on your machine, if you have more than one. The interface's promiscuous flag is set only when a facility is started, and turned off when it exits. However, if promiscuous mode was already set when a facility was started, it remains set on exit. If multiple instances of IPTraf are started, the promiscuous setting is restored only upon exit of the last facility. Note Do not use other programs that change the interface's promiscuous flag at the same time you're using IPTraf. The programs can interfere with each other's expected operations. While IPTraf tries to obtain the initial setting of any promiscuous flags for restoration upon exit, other programs may not be as well-behaved, and they may turn off the promiscuous flags while IPTraf is still monitoring. Color Turn this on with color monitors. Turn it off with black-and- white monitors or non-color terminals (like xterms). Changes to this setting will take effect the next time the program is started. Color is on by default on consoles and color xterms, off on non-color terminals like xterms and VT100s. Logging When this option is active, IPTraf will log information to a disk file, which can be examined or analyzed later. Since IPTraf 2.4.0, IPTraf prompts you for the name of the file to which to write the logs. It will provide a default name, which you are free to accept or change. The IP traffic monitor and LAN station monitor will generate a log file name that is based on what instance they are (first, second, and so on). The general interface statistics' default log file name is constant, because it listens to all interfaces at once, and only one instance can run at one time. The other facilities generate a log file name based on the interface they're listening on. See the descriptions on the facilities above for the default log file names. Press Enter to accept the log file name, or Ctrl+X to cancel. Canceling will turn logging off for that session. The IP traffic monitor will write the following pieces of information to its log file: Start of the traffic monitor Receipt of the first TCP packet for a connection. If that packet is a SYN, (SYN) will be indicated in the log entry. (Of course, the traffic monitor may start in the middle of established connections. It will still count those packets. This also explains why some connection entries may become idle if the traffic monitor is started in the middle of a half-closed connection, and miss the first FIN. Such entries time out in a while.) Receipt of a FIN (with average flow rate) ACK of a FIN Timeouts of TCP entries (with average flow rate) Reset connections (with average flow rate) Everything that appears in the bottom window of the traffic monitor Stopping of the traffic monitor Each log entry includes the date and time the entry was written. Logging is also affected by the defined filters. Log files can grow very fast, so be prepared with plenty of free space and delete unneeded logs. Log write errors are not indicated. Copies of the interface statistics, TCP/UDP statistics, packet size statistics, and LAN host statistics are also written to the log files at regular intervals. See Log Interval... in this chapter. IPTraf closes and reopens the active log file when it receives a USR1 signal. This is useful in cases where a facility is run for long periods of time but the log files have to be cleared or moved. To clear or move an active log file, rename it first. IPTraf will continue to write to the file despite the new name. Then use the UNIX kill command to send the running IPTraf process a USR1 signal. IPTraf will then close the log file and open another with the original name. You can then safely remove or delete the renamed file. Do not delete an open log file. Doing so will only result in a file just as large but filled with null characters (ASCII code 0). Logging comes disabled by default. The USR1 signal is caught only if logging is enabled, it is ignored otherwise. A valid specification of -L on the command line with automatically enable logging for that particular session. The saved configuration setting is not affected. Activity mode Toggles activity indicators in the interface and LAN statistics facilities between kilobits per second (kbits/s) or kilobytes per second (kbytes/s). The default setting is kilobits per second. Source MAC addrs in traffic monitor When enabled, the IP traffic monitor retrieves the packets' source MAC addresses if they came in on an Ethernet, FDDI, or PLIP interface. The addresses appear in the lower window for non-TCP packets, while for TCP connections, they can be viewed by pressing M. No such information is displayed if the network interface doesn't use MAC addresses (such as PPP interfaces). This can be used to determine the actual source of the packets on your local LAN. The traffic monitor also logs the MAC addresses with this option enabled. The default setting is off. Timers The Timers... submenu allows you to IPTraf's interval and timeout functions.
The Timers configuration submenu
TCP Timeout This figure determines the amount of time (in minutes) a connection entry may remain idle before it becomes eligible for replacement by a new connection. The default is 15 minutes. You may want to reduce this on an isolated (not connected to the Internet) LAN or a LAN connected to the Internet with high-speed links. Just enter the new value and press Enter. You can press Ctrl+X to leave the current value unchanged. Log Interval This figure determines the number of minutes between logging of interface statistics, TCP/UDP figures, and LAN host statistics. The default is 60 minutes. This figure is meaningless if logging is disabled. This configuration item can be overridden with the -I when a facility is directly invoked from the command line (not accessed via the main menu), and remains effective for that particular session. The configured value is not affected. Screen Update Interval This value determines the rate in seconds at which the screen is updated. The default is 0, which means the screen is updated as fast as possible, giving close-to-realtime reflection of network activity. However, this high-speed update can cause incredible amounts of traffic if IPTraf is run on a remote terminal (e.g. a Telnet or Secure Shell session). You can set this to a higher value, such as 1 or 2 seconds to slow down the updates. This figure does not affect the rate of data capture. Only the screen refresh is affected. The figures are still updated as fast as possible, although the figure display will no longer be as close to realtime. The default setting is 0, which shouldn't be a problem on the console. Set it to a slightly higher value on remote terminals or slow links. The setting affects all monitoring facilities. Note Updating the screen is one of the slowest operations in a program. Older versions of IPTraf had a problem once network activity became very high. Because each packet caused a screen update, IPTraf began spending more time with the screen updates, causing a loss of packets once network activity reached a certain point. However, since many users like rapid counts on their screen, a compromise was incorporated. Even when the screen update interval is set to 0, there is still a 50ms delay between screen updates (except the LAN station monitor, which has a 100 ms delay). This is still visually fast, but provides more time to the packet capture routine. Higher delays may result in better accuracy of counts and activity. In any case, this setting only affects screen updates. Capture still proceeds as fast as possible. TCP closed/idle persistence This parameter determines the interval (in minutes) at which the IP Traffic Monitor clears from the TCP display window all closed, idle, and timed out entries. Enter 0 to keep such entries on the screen indefinitely, disappearing only when replaced by new connections. Note The TCP timeout... option only tells IPTraf how long it should take before a connection should be considered idle and open to replacement by new connections. This does not determine how long it remains onscreen. The TCP closed/idle persistence... parameter flushes entries that have been closed or reset, or idle for the number of minutes defined by the TCP timeout... option. Custom Information The remaining configuration items allow you to enter information which IPTraf uses for its displays and logs. Additional ports Select this item to enter a port number to be included in the TCP/UDP counts in the TCP/UDP service statistics main menu item described above. By default, port numbers above 1023 are not monitored. If you do have a higher-numbered port to monitor, enter it here. You will see two fields. If you have only one port to enter, just fill up the first field. To specify a range, fill both fields, the first port in the first field, the last port in the second field. You can select this option multiple times to add more values or ranges. Delete port/range Select this item to remove a higher-numbered port number or port range you entered earlier with the Additional ports... option. A window will come up containing the entered ports and ranges. Select the entry you want delete and press Enter. LAN Station Identifiers The LAN station statistics facility monitors stations based on their respective MAC addresses. The hexadecimal notation of these addresses make them even more difficult to remember than the dotted-decimal IP addresses, so these facilities were added to help you better determine which station is which. Selecting the Ethernet/PLIP host descriptions... or FDDI/Token Ring host descriptions... options brings up a submenu asking you to add, edit, or delete descriptions. To add a new description, select the Add description... option. A dialog box will appear, asking you for the MAC address and an appropriate description. Type in the address in hexadecimal notation with no punctuation of any kind. The dialog box is case-insensitive for the address; the alphabetical digits A to F will be stored in lowercase. Use the Tab key to move between fields and Enter to accept. Press Ctrl+X to discard this dialog and return to the main menu. The description may be anything: the IP address, a fully-qualified domain name, or a description of your liking as long as the field can hold. Enter as many descriptions as you need. Press Ctrl+X at a blank dialog after you have entered the last entry These descriptions will be displayed alongside the MAC addresses in the LAN station monitor, together with the type of frame (Ethernet, PLIP, or FDDI). An existing address or description may be edited by selecting the Edit description... option from the submenu. A panel will appear with a list of existing address descriptions. Select the one you wish to edit and press Enter. A dialog box identical to that when you add a description will appear with prefilled fields. Just backspace over and edit the fields. Press Enter to accept or Ctrl+X to cancel. Selecting the Delete description... submenu item brings up the selection panel. Select the description you want to delete and press Enter. You can also press Ctrl+X to cancel the operation. IPTraf 2.4 and later also recognizes the /etc/ethers file. Should a hardware address be present in the IPTraf definition files and in /etc/ethers, the IPTraf definition will be used. Note The description file for Ethernet and PLIP is ethernet.desc, while the FDDI and Token Ring mappings are stored in fddi.desc in the IPTraf working directory. These files are in colon-delimited text format. Database engines or custom scripts can be told to append data lines to those files. Each line follows this simple format: address:description For example 00201e457e:Cisco 3640 gateway Do not put colons, periods, or any invalid characters in the MAC address. Background Operation IPTraf's facilities can be placed in the background solely for logging. When running in the background, it doesn't display any output on the screen, and doesn't receive input from the keyboard, and drops you back to the shell. Before starting a statistical facility in the background, configure IPTraf in the usual way (set filters, add TCP/UDP ports, etc). Once that's done, exit all instances of IPTraf on the system, then invoke IPTraf from the command line with the parameter to start the facility you want, the timeout (-t) parameter if you wish, and the -B parameter to actually daemonize the program. For example, to run the IP traffic monitor in the background for all interfaces, issue the command iptraf -i all -B To run the detailed interface statistics on interface eth0 for 5 minutes in the background: iptraf -d eth0 -t 5 -B If the timeout parameter is not specified, the facility will run until the process receives a USR2 signal. To stop a facility in the background, do a ps x at the command line, and find the process id (pid) of the iptraf process you're looking for. Then send that process a USR2 signal with the kill command: kill -USR2 pid Since IPTraf cannot send error messages to the terminal, all messages are written to the file daemon.log in the IPTraf logging directory. The -B parameter automatically enables logging regardless of its configured setting. The parameter is ignored if not used with one of the parameters to start a facility from the command line. The log file can be specified with the -L command-line parameter. If this parameter is not specified, the default log file name for the facility will be used (see the descriptions of the facilities above for the default log name patterns). If you don't specify an path, the log file will be placed in /var/log/iptraf. The logging interval for all facilities (except the IP traffic monitor) can also be overriden with the -I command-line parameter. Messages IPTraf's messages are presented in two ways. In interactive mode, messages are displayed in a distictive message box. In daemon (background) mode, appropriate messages are written to the iptraf.log file in the IPTraf log directory (normally /var/log/iptraf. IPTraf Messages Unable to create config file IPTraf cannot create the configuration file. The most likely cause of this is that you didn't properly install the program, and the necessary directory /var/local/iptraf does not exist. Can also be generated if you have a disk problem or if you have too many files open. Unable to read config file The configuration record cannot be read. You most likely have a disk problem. Unable to write config file The configuration file cannot be written. You either have a disk problem, or (more likely), your disk is full. Enter an appropriate description for this filter Enter something to clearly describe the filter you are defining. Error loading filter list file IPTraf cannot access the list of defined TCP or UDP filters. Can also be an indicator of a bad disk. Error writing filter list file The filter list file cannot be written to. You may have trouble accessing your filters. Unable to read TCP/UDP/misc IP filter file IPTraf cannot read the filter data off the file. Could be caused by a bad disk. Error opening filter data file IPTraf cannot open the filter file. Could be caused by a shortage of file descriptors or a bad disk. Unable to write filter data IPTraf cannot add the newly defined filter to the filter list. This may be due to a bad disk. Cannot create filter data file IPTraf cannot create the filter record file. The defined filter is lost. Unable to save filter changes IPTraf cannot save the changes you made to the filter. You probably have a disk error. Unable to write filter state information The current state of the filters cannot be saved. IPTraf will be unable to correctly reload the filters the next time it's started. This can be caused by a bad disk or improper installation. Unable to save interface flags IPTraf was unable to save the flags of the network interfaces. This is probably due to a bad installation or full filesystem. Unable to retrieve saved interface flags IPTraf was unable to retrieve the save interface flags. Probably again due to a bad installation or full filesystem. protocol filter data file in use; try again later Filter state file in use; try again later Another IPTraf process is modifying the TCP, UDP or miscellaneous IP filter data or the filter state file and has locked the files or file. Try again once the other IPTraf process has terminated or completed its modifications and unlocked the files. Unable to resolve hostname The indicated host name in the filter cannot be resolved into an IP address. Check the local hosts database /etc/hosts or your machine's DNS configuration or DNS server. The filter parameters will not be used. Unable to open host description file IPTraf cannot open the file containing the descriptions for Ethernet or FDDI addresses. Could be due to a bad disk or a hit on the file descriptor limit. Unable to write host description IPTraf was unable to write the description record for this Ethernet or FDDI address. Could be due to a bad disk or corrupted filesystem. No descriptions You tried to edit or delete a description with no previous descriptions defined. Cannot open log file There is a problem opening the log file. There is most likely a problem with the disk, or there are too many open files. Unable to obtain interface list IPTraf was unable to retrieve the list of network interfaces from the /proc filesystem. This may be due to a badly configured kernel. IPTraf needs /proc filesystem support. No active interfaces. Check their status or the /proc filesystem. IPTraf found no active interfaces. Either all interfaces are down or the /proc/net/dev file was empty or unavailable. Activate at least one interface or check the /proc/net/dev file. Unable to obtain interface parameters for interface The system call to retrieve the interface's flags failed. Check your interface or kernel driver. Promisc change failed for interface The system call to change the promiscuous flag failed. Check your interface or its kernel driver. Unable to open raw socket for flag change IPTraf was unable to open the necessary socket for the promiscuous change operation. May be due to a shortage of file descriptors. Unable to open socket for MTU determination Returned by the facility for detailed interface statistics if the raw socket's opening sequence failed. The facility will abort. Unable to open raw socket IPTraf was unable to open the raw socket for packet capture. May be due to a shortage of file descriptors. Reminder IPTraf 2.x.x requires Linux kernel 2.2.x, with the Packet Socket option compiled in or installed as a module. IPTraf 2.x will return this error on a pre-2.2 kernel or on a 2.2 kernel without Packet Socket. Unable to obtain interface MTU The detailed statistics facility was unable to obtain the maximum transmission unit (MTU) for the selected interface. The facility will abort. Specified interface not supported The interface specified with the -i, -d, -s, -l, or -z command-line parameters is not supported by IPTraf. Specified interface not active The interface specified with the -i, -d, -s, -l, or -z command-line parameters is supported, but not currently activated. Fatal: memory allocation error May occur if you have too little memory to allocate for windows, the menu system, or dialog boxes. IPTraf tries to prevent further allocations if memory runs out during a monitor. However, this could also mean a bug if you're reasonably sure you're not out of memory. An instructional message on bug reporting follows this message. Technical note This is actually a response to the segmentation fault error (SIGSEGV). This program can be run only by the system administrator IPTraf normally does not allow anybody but uid 0 (root) to run it. This measure is included for safety reasons. See the section on recompiling the program below if you want to override this. This feature is built in, and not part of the configuration Your TERM variable is not set The TERM (terminal type) environment variable must be set to a valid terminal type so that the screen management routines can function properly. Set it to the appropriate terminal type. Linux consoles typically have their TERM variables set to linux. Received TERM signal Not related to the previous message. The TERM (terminate) signal is normally used to gracefully shut down a program. This message simply indicates that the TERM signal was caught and IPTraf is attempting to shut down as gracefully as possible. Invalid option or missing parameter, use iptraf -h for help The -i, -d, -s, -l, or -z options were specified but no interface was specified on the command line. These parameters require a valid interface name (or all for -i or -l). This message also appears if an unknown option is passed to the iptraf command. Warning: unable to tag this process IPTraf normally tags itself when it runs to prevent multiple instances of the statistical facilities from running. This message means the program was unable to create the necessary tag file. This may be due to a bad or improper installation. Try running the make install procedure or the Setup in the distribution's top-level directory. Warning: unable to tag facility IPTraf was unable to create the tag file for the facility you started. The facility will still run, but other instances of IPTraf that may be running simultaneously will allow the same facility to run. This may cause both instances of the facility to malfunction. This could be due to a bad disk or bad installation. facility already running/listening on interface The facility you tried to start is currently running on the indicated interface in another IPTraf process on the machine. This restriction is placed to prevent conflicts involving internal sockets or the log files. General interface statistics already active in another process Only one instance of the general interface statistics can run at a time. Duplicate port/range entry You entered a port number or range that was already added to the list of additional ports to be monitored by the TCP/UDP service monitor No custom ports There are no ports or port ranges earlier added. There's nothing to delete. Can't start rvnamed; lookups will block IPTraf cannot start the rvnamed daemon; probably due to a bad installation. IPTraf will fall back to blocking lookups. Can't spawn new process; lookups will block IPTraf cannot start a new process. This may be due to memory shortage. IPTraf will fall back to blocking lookups. Fork error, IPTraf cannot run in background IPTraf cannot start a new process, and can go into the background. This may be due to memory shortage. IPTraf aborts. No memory for new filter entry IPTraf was unable to allocate memory for a new filter entry. Most likely due to memory shortage. Memory Low This indicator appears if memory runs low due to a lot of entries in a facility. Should critical functions fail (window creation, internal allocation), the program could terminate with a segmentation violation. Note Any message or indicator about low memory means that your system does not have enough memory to handle the entries. It is almost certain that sooner or later, IPTraf or other applications will abort due to the failure of important system calls or library functions. Memory must be added right away. IPC Error This indicator appears if an error occurs receiving data from the rvnamed program (IPC stands for Interprocess Communication). This indication should not occur under normal circumstances. Report instances of this condition and the circumstances under which it happens. You may also include data from the rvnamed.log file. Error opening terminal: terminal The screen management routines cannot find the terminfo entry for your terminal. IPTraf expects the terminfo database located in /usr/share/terminfo. This error could occur when your terminfo database is located somewhere else. See the section on controlling the terminfo search path. This will end your IPTraf session In interactive mode IPTraf asks you to confirm your exit command. Press Enter to return to the shell or any other key to cancel your command and return to the main menu. rvnamed Messages As a daemon, rvnamed does not send messages to the screen. It writes its messages to the file rvnamed.log in the IPTraf log directory. Unable to open child communication socket rvnamed was unable to open the communication endpoint for data reception from the children it creates. This is highly unusual, and should it occur, report the circumstances. Unable to open client communication socket rvnamed was unable to open the communication endpoint for data exchange with the IPTraf program. This is highly unusual, and should it occur, report the circumstances. Error binding client communication socket Error binding child communication socket rvnamed was unable to assign a name to the indicated communication socket. This may be due to a bad, full, or corrupted filesystem. Fatal error: no memory for descriptor monitoring rvnamed ran out of memory. IPTraf will resort to blocking, and may freeze. Error on fork, returning IP address rvnamed had a problem spawning a copy of itself to resolve the IP address. rvnamed will simply return the IP address in its literal, dotted-decimal notation. IPTraf will still function normally. This may be due to lack of memory or a process limit hit. Maximum child process limit reached rvnamed has reached its maximum number of child processes. This is intended as a "brake" to prevent too many rvnamed children from hogging your computer's resources and possibly crashing it. Unless IPTraf is monitoring an extremely busy network without filters, this shouldn't happen, at least, not that often. If you notice this message, try applying filters or check your DNS server. Many times, this can happen when the DNS server goes down for whatever reason, and you have rvnamed children taking too long to resolve. GNU Free Documentation License Version 1.1, March 2000
Copyright (C) 2000 Free Software Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.
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