portsentry - detect portscan activity

Author

portsentry was written by Craig H. Howland <crowland@users.sf.net>.

       This  manual  page  was  stitched  together  by Guido Guenther <agx@debian.org>, for the Debian GNU/Linux
       system (but may be used by others). Some parts are just a cut and paste from the original documentation.

                                                                                                   PORTSENTRY(8)

Configuration Files

portsentry keeps all its configuration files in /etc/portsentry.portsentry.conf is portsentry's main
configuration file. See portsentry.conf(5) for details.

The file portsentry.ignore contains a list of all hosts that are ignored, if they connect to a tripwired
port. It should contain at least the localhost(127.0.0.1), 0.0.0.0 and the IP addresses of all local
interfaces. You can ignore whole subnets by using a notation <IP Address>/<Netmask Bits>. It is *not*
recommend putting in every machine IP on your network. It may be important for you to see who is
connecting to you, even if it is a "friendly" machine. This can help you detect internal host compromises
faster.

If you use the /etc/init.d/portsentry script to start the daemon, portsentry.ignore is rebuild on each
start of the daemon using portsentry.ignore.static and all the IP addresses found on the machine via
ifconfig.

/etc/default/portsentry specifies in which protocol modes portsentry should be startet from
/etc/init.d/portsentry There are currently two options:

TCP_MODE=
either tcp, stcp or atcp (see OPTIONS above).

UDP_MODE=
either udp, sudp or audp (see OPTIONS above).

The options above correspond to portsentry's commandline arguments. For example TCP_MODE="atcp" has the
same effect as to start portsentry using portsentry-atcp. Only one mode per protocol can be started at
a time (i.e. one tcp and one udp mode).

Description

       This  manual  page documents briefly the portsentry command.  This manual page was written for the Debian
       GNU/Linux distribution because the original program does not have a manual page.

       portsentry is a program that tries to detect portscans on network interfaces with the ability  to  detect
       stealth  scans.  On  alarm portsentry can block the scanning machine via hosts.deny (see hosts_access(5),
       firewall rule (see ipfwadm(8),ipchains(8) and iptables(8)) or dropped route (see route(8)).

Files

/etc/portsentry/portsentry.conf main configuration file

       /etc/portsentry/portsentry.ignore
              IP addresses to ignore

       /etc/portsentry/portsentry.ignore.static
              static IP addresses to ignore

       /etc/default/portsentry
              startup options

       /etc/init.d/portsentry
              script responsible for starting and stopping the daemon

       /var/lib/portsentry/portsentry.blocked.*
              blocked hosts(cleared upon reload)

       /var/lib/portsentry/portsentry.history
              history file

Name

       portsentry - detect portscan activity

Options

       For details on the various modes see /usr/share/doc/portsentry/README.install-tcp   tcp   portscan   detection   on   ports   specified   under   TCP_PORTS   in   the   config   file
              /etc/portsentry/portsentry.conf.

       -stcp  As above but additionally detect stealth scans.

       -atcp  Advanced  tcp or inverse mode. Portsentry binds to all unused ports below ADVANCED_PORTS_TCP given
              in the config file /etc/portsentry/portsentry.conf.

       -udp   udp   portscan   detection   on   ports   specified   under   UDP_PORTS   in   the   config   file
              /etc/portsentry/portsentry.conf.

       -sudp  As above but additionally detect "stealth" scans.

       -audp  Advanced  udp or inverse mode. Portsentry binds to all unused ports below ADVANCED_PORTS_UDP given
              in the config file /etc/portsentry/portsentry.conf.

Synopsis

portsentry[-tcp|-stcp|-atcp]portsentry[-udp|-sudp|-audp]