.TH IFTOP 8 .\" .\" iftop.8: .\" Manual page for iftop. .\" .\" $Id$ .\" .SH NAME iftop - display bandwidth usage on an interface by host .SH SYNOPSIS \fBiftop\fP \fB-h\fP | [\fB-d\fP] [\fB-p\fP] [\fB-i\fP \fIinterface\fP] [\fB-f\fP \fIfilter code\fP] .SH DESCRIPTION \fBiftop\fP listens to network traffic on a named \fIinterface\fP, or \fBeth0\fP if none is specified, and displays a table of current bandwidth usage by pairs of hosts. When run, \fBiftop\fP displays, for each pair of hosts, the rate at which data is sent and received averaged over 2, 10 and 40 second intervals. The direction of data flow is indicated by arrows, <= and =>. In addition, a simple bar graph shows the 10-second average. The pairs of hosts which consume the most bandwidth are displayed at the top of the screen, and totals for all hosts are shown at the bottom of the screen. By default, \fBiftop\fP will look up the hostnames associated with addresses it finds in packets. This can cause substantial traffic of itself, and may result in a confusing display. You may wish to suppress display of DNS traffic by using filter code such as \fBnot port domain\fP, or switch it off entirely, by using the \fB-d\fP option or by pressing \fBR\fP when the program is running. By default, \fBiftop\fP shows all IP packets that pass through the filter, and the direction of the packet is determined according to the direction the packet is moving across the interface. Using the \fB-n\fP option it is possible to get \fBiftop\fP to show packets entering and leaving a given network. For example, \fBiftop -n 10.0.0.0/255.0.0.0\fP will analyse packets flowing in and out of the 10.* network. \fBiftop\fP must be run as root. Some other filter ideas: .TP \fBnot ether host ff:ff:ff:ff:ff:ff\fP Ignore ethernet broadcast packets. .TP \fBport http and not host \fP\fIwebcache.example.com\fP Count web traffic only, unless it is being directed through a local web cache. .TP \fBicmp\fP How much bandwith are users wasting trying to figure out why the network is slow? .SH OPTIONS .TP \fB-h\fP Print a summary of usage. .TP \fB-d\fP Don't do hostname lookups. This setting may be altered at run time. .TP \fB-p\fP Run in promiscuous mode, so that traffic which does not pass directly through the specified interface is also counted. .TP \fB-i\fP \fIinterface\fP Listen to packets on \fIinterface\fP. .TP \fB-f\fP \fIfilter code\fP Use \fIfilter code\fP to select the packets to count. Only IP packets are ever counted, so the specified code is evaluated as \fB(\fP\fIfilter code\fP\fB) and ip\fP. .TP \fB-n\fP \fInet/mask\fP Specifies a network for traffic analysis. If specified, iftop will only include packets flowing in to or out of the given network, and packet direction is determined relative to the network boundary, rather than to the interface. .SH SEE ALSO .BR tcpdump (8), .BR pcap (3), .BR driftnet (1) .SH AUTHOR Paul Warren .SH VERSION $Id$ .SH COPYING This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.