These are just installation notes and this should not be considered a complete howto.
The fail2ban script runs as a daemon and bans an IP address after too many failed login attempts. We use it for blocking failed login attempts for SSH, ProFTP and Postfix.
Fail2ban is very effective at stopping the brute-force attacks now common to all Internet-connected hosts. We have found it reliable and functional without causing problems.
Installation on Centos 5
wget http://superb-west.dl.sourceforge.net/sourceforge/fail2ban/fail2ban-0.8.1.tar.bz2
tar -xjvf fail2ban-0.8.1.tar.bz2
cd fail2ban-0.8.1
python setup.py install
vi /etc/fail2ban/jail.conf
Enable only the sections you need and do them one at a time. We enable SSH and ProFTP (both use /var/log/secure) as well as Postfix.
Set your local networks and any other networks you consider 'safe'. You certainly don't want to block your own clients!
ignoreip = 127.0.0.1 192.245.12.0/24 207.182.32.0/19 204.27.149.0/24
Installation on SME 7
NEEDS Python 2.4!! (NOT CURRENTLY AVAILABLE)
(SME 7 uses /var/log/messages)
Startup
cp files/redhat-initd /etc/init.d/fail2ban
chkconfig --add fail2ban
chkconfig fail2ban on
service fail2ban start
Tools
Show failed SSH logins by date:
cat /var/log/secure* | grep 'Failed password' | grep sshd | awk '{print $1,$2}' | sort | uniq -c
Search for correct log file:
grep such /var/log/messages*
grep ftp /var/log/messages*
grep -r NOQUEUE /var/log
This should match Postfix bans:
grep rejected /var/log/maillog
Configuration
Adjust the following sample configuration files to your needs.
# Fail2Ban jail.local configuration file
################################################
# www.sonoracomm.com
#
# The DEFAULT allows a global definition of the options. They can be override
# in each jail afterwards.
[DEFAULT]
# ignore Opus IP ranges
ignoreip = 127.0.0.1 192.245.12.0/24 207.182.32.0/19 204.27.149.0/24
# "bantime" is the number of seconds that a host is banned.
bantime = 600
# A host is banned if it has generated "maxretry" during the last "findtime"
# seconds.
findtime = 600
# "maxretry" is the number of failures before a host get banned.
maxretry = 3
# Don't know how well other backend options work.
backend = polling
[ssh-iptables]
enabled = true
filter = sshd
action = iptables[name=SSH, port=ssh, protocol=tcp]
sendmail-whois[name=SSH, dest=
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, sender=
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]
logpath = /var/log/secure
maxretry = 3
[proftpd-iptables]
enabled = true
filter = proftpd
action = iptables[name=ProFTPD, port=ftp, protocol=tcp]
sendmail-whois[name=ProFTPD, dest=
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, sender=
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]
logpath = /var/log/secure
maxretry = 3
[postfix]
enabled = true
filter = postfix
action = iptables[name=Postfix, port=smtp, protocol=tcp]
sendmail-whois[name=Postfix, dest=
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, sender=
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]
logpath = /var/log/maillog
maxretry = 5
# Fail2Ban filter.d/postfix.local configuration file
################################################
# www.sonoracomm.com
#
[Definition]
failregex = reject: RCPT from (.*)\[<HOST>\]: 554
reject: RCPT from (.*)\[<HOST>\]: 550
reject: RCPT from (.*)\[<HOST>\]: 450
ignoreregex =
# Fail2Ban action.d/sendmail-whois.local configuration file
################################################
# www.sonoracomm.com
#
[Definition]
actionstart = echo -en "Subject: [Fail2Ban] <name>: started
From: Fail2Ban <<sender>>
To: <dest>\n
Hi,\n
The jail <name> has been started successfully.\n
Regards,\n
Fail2Ban" | /usr/sbin/sendmail -f <sender> <dest>
actionstop = echo -en "Subject: [Fail2Ban] <name>: stopped
From: Fail2Ban <<sender>>
To: <dest>\n
Hi,\n
The jail <name> has been stopped.\n
Regards,\n
Fail2Ban" | /usr/sbin/sendmail -f <sender> <dest>
actioncheck =
actionban = echo -en "Subject: [Fail2Ban] <name>: banned <ip>
From: Fail2Ban <<sender>>
To: <dest>\n
Hi,\n
The IP <ip> has just been banned by Fail2Ban after
<failures> attempts against <name>.\n\n
Here are more information about <ip>:\n
`/usr/bin/dig -x <ip>`\n
Regards,\n
Fail2Ban" | /usr/sbin/sendmail -f <sender> <dest>
actionunban =
[Init]
name = default
dest = root
sender = fail2ban
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