[TOOL] Sessionlimit - Rate Session Limiting Capabilities For OpenBSD's PF

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Sessionlimit - Rate Session Limiting Capabilities For OpenBSD's PF
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SUMMARY



DETAILS

Sessionlimit is a tool designed to interact with OpenBSD's PF in order to
contain the intruders activities after a compromise of a honeypot. It can
detect when a scan or DoS is initiated from a honeypot -- once the
activity is detected a rule is inserted to PF in order to block the
outgoing traffic. This rule is removed after specified time.

The sessionlimit program works by monitoring the state table for the
outgoing sessions. It blocks source IPs according to one of the following
criterias:

1. When the number of states associated with a source IP is increasing
too fast;
2. When the source IP has reached a predefined limit of outgoing
connections. The default is 20 connections.
3. When the number of bytes associated with an ICMP state has reached a
predefined limit. The default is 65k. This was developed to block stupid
DoS attacks, like ping -f victim;

If any of the above conditions is true sessionlimit inserts a new rule at
the top of the active ruleset, blocking all traffic from the offending IP
to the outside. The offending outgoing traffic will be blocked, but it is
important to note that the intruder's interactive session won't be
affected, since he is using an incoming keep state rule.

After some time (the default is 30 minutes), the rule will expire and will
be removed from the active ruleset.

It is important to note that the original intruder's incoming session is
not affected by the new rule. This means that the intruder can still
interact with the honeupot, but any new outgoing connection he tries to
initiate will be blocked.

To download the tool:
<http://www.lac.inpe.br/security/honeynet/tools/sessionlimit-0.3.tar.gz>
http://www.lac.inpe.br/security/honeynet/tools/sessionlimit-0.3.tar.gz


ADDITIONAL INFORMATION

The information has been provided by <mailto:jessen@xxxxxx> Klaus
Steding-Jessen and <mailto:cristine@xxxxxx> Cristine Hoepers.
To keep updated with the tool visit the project's homepage at:
<http://www.lac.inpe.br/security/honeynet/#tools>
http://www.lac.inpe.br/security/honeynet/#tools



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