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.\" netsniff-ng - the packet sniffing beast
.\" Copyright 2013 Daniel Borkmann.
.\" Subject to the GPL, version 2.
.TH FLOWTOP 8 "03 March 2013" "Linux" "netsniff-ng toolkit"
.SH NAME
flowtop \- top-like netfilter TCP/UDP/SCTP/DCCP/ICMP(v6) flow tracking
.SH SYNOPSIS
\fB flowtop\fR { [\fIoptions\fR] }
.SH DESCRIPTION
flowtop is a top-like connection tracking tool that can run on an end host or
small home router. It is able to present TCP, UDP/UDP-lite, SCTP, DCCP, ICMP(v6)
flows that have been collected by the kernel's netfilter connection tracking
framework, thus no packet capturing in user space needs to be done.
flowtop is able to give you a quick overview of current connections on your
local system, e.g. for debugging purposes or to answer questions like:
* If you access website X, what other connections are being opened in
the background that I'm not aware of?
* What connections are active that pass ones router?
* I have this proprietary binary Y, where does it connect to?
* To which countries am I sending my data?
* Are there any suspicious background connections on my machine?
* How many connections has binary Z currently active?
The following information will be presented in flowtop's output:
* Application name and PID when run on local machine
* Reverse DNS for source and destination
* Geo-location information (country, city)
* Used protocols (IPv4, IPv6, TCP, UDP, SCTP, ICMP, ...)
* Flow port's service name heuristic
* Transport protocol state machine information
In order for flowtop to work, netfilter/iptables must be active resp. running
on your machine, thus kernel-side connection tracking is active.
flowtop's intention is just to get a quick look over your active connections.
If you want to have logging, have a look at netfilter's conntrack(8) tools
instead.
.SH OPTIONS
.SS -4, --ipv4
Display IPv4 flows. That's default when flowtop is started without
any arguments.
.SS -6, --ipv6
Display IPv6 flows. That's default when flowtop is started without
any arguments.
.SS -T, --tcp
Display TCP flows. That's default when flowtop is started without
any arguments.
.SS -U, --udp
Display UDP and UDP-lite flows.
.SS -D, --dccp
Display DCCP flows.
.SS -I, --icmp
Display ICMP version 4 and version 6 flows.
.SS -S, --sctp
Display SCTP flows.
.SS -s, --show-src
Also show source information of the flow, not only destination information.
.SS -u, --update
The built-in database update mechanism will be invoked to get Maxmind's
latest database. To configure search locations for databases, the file
/etc/netsniff-ng/geoip.conf contains possible addresses. Thus, to save
bandwidth or for mirroring Maxmind's databases (to bypass their traffic
limit policy), different hosts or IP addresses can be placed into geoip.conf,
separated by a newline.
.SS -v, --version
Show versioning information.
.SS -h, --help
Show user help.
.SH USAGE EXAMPLE
.SS flowtop
Default ncurses output for flowtop that tracks IPv4, IPv6 flows for TCP.
.SS flowtop -46UTDISs
This example enables maximum display options for flowtop.
.SH CONFIG FILES
Under /etc/netsniff-ng/ there are the following files stored that are used
by flowtop and can be extended if wished:
* tcp.conf - TCP port/services map
* udp.conf - UDP port/services map
* geoip.conf - GeoIP database mirrors
.SH BUGS
During fairly high till high connection tracking updates, flowtop's scrolling
can become shortly unresponsive. The right fix would be to replace flowtop's
connection management backend with a better design resp. locking approach.
Still on todo.
.SH LEGAL
flowtop is licensed under the GNU GPL version 2.0.
.SH HISTORY
.B flowtop
was originally written for the netsniff-ng toolkit by Daniel Borkmann. It
is currently maintained by Tobias Klauser <tklauser@distanz.ch> and Daniel
Borkmann <dborkma@tik.ee.ethz.ch>.
.SH SEE ALSO
.BR netsniff-ng (8),
.BR trafgen (8),
.BR mausezahn (8),
.BR ifpps (8),
.BR bpfc (8),
.BR astraceroute (8),
.BR curvetun (8)
.SH AUTHOR
Manpage was written by Daniel Borkmann.
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