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Fail2ban: Denial of Service


1.  Gentoo Linux Security Advisory

Version Information

Advisory Reference GLSA 200702-05 / fail2ban
Release Date February 16, 2007
Latest Revision February 16, 2007: 01
Impact normal
Exploitable remote
Package Vulnerable versions Unaffected versions Architecture(s)
net-analyzer/fail2ban < 0.6.2 >= 0.6.2 All supported architectures

Related bugreports: #157166


A flaw in Fail2ban may allow remote attackers to deny access to arbitrary hosts.

2.  Impact Information


Fail2ban monitors log files for failed authentication attempts and can block hosts responsible for repeated attacks.


A flaw in the method used to parse log entries allows remote, unauthenticated attackers to forge authentication attempts from other hosts.


A remote attacker can add arbitrary hosts to the block list, denying legitimate users access to a resource.

3.  Resolution Information


There is no known workaround at this time.


All Fail2ban users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=net-analyzer/fail2ban-0.6.2"

4.  References


Page updated February 16, 2007

Summary: This is a Gentoo Linux Security Advisory

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