Fail2ban

Languages:

English

Fail2ban for SME Server

	Skill level: Easy
	The instructions on this page can be followed by a beginner.

Maintainer

Daniel B.
Firewall Services
mailto:daniel@firewall-services.com

Description

Fail2ban operates by monitoring log files (e.g. /var/log/pwdfail, /var/log/auth.log, etc.) for selected entries and running scripts based on them. Most commonly this is used to block selected IP addresses that may belong to hosts that are trying to breach the system's security. It can ban any host IP that makes too many login attempts or performs any other unwanted action within a time frame defined by the administrator. Fail2ban is typically set up to unban a blocked host within a certain period, so as to not "lock out" any genuine connections that may have been temporarily misconfigured. However, an unban time of several minutes is usually enough to stop a network connection being flooded by malicious connections, as well as reducing the likelihood of a successful dictionary attack.

	Tip:
	fail2ban is not only a tool against brute force attack on ssh but it can be a tool useful against http protocol attacks or spam attacks on your server. See the jail section

Requirements

This contrib has been developped and tested on SME Server 8 and later. It probably won't work on SME 7.

Installation

Configure Firewall-Services's repository:

db yum_repositories set fws repository \
BaseURL http://repo.firewall-services.com/centos/\$releasever \
EnableGroups no GPGCheck yes \
Name "Firewall Services" \
GPGKey http://repo.firewall-services.com/RPM-GPG-KEY \
Visible yes status disabled

Configure EPEL's repository: For SME 8.x,

/sbin/e-smith/db yum_repositories set epel repository \
Name 'Epel - EL5' \
BaseUrl 'http://download.fedoraproject.org/pub/epel/5/$basearch' \
MirrorList 'http://mirrors.fedoraproject.org/mirrorlist?repo=epel-5&arch=$basearch' \
EnableGroups no \
GPGCheck yes \
GPGKey http://dl.fedoraproject.org/pub/epel/RPM-GPG-KEY-EPEL \
Visible no \
status disabled

signal-event yum-modify

• install the rpms

yum --enablerepo=fws --enablerepo=epel install smeserver-fail2ban

	Note:
	you have to install the fail2ban version of fws repository and not the epel version

• Appply the needed configuration:

expand-template /etc/rc.d/init.d/masq
/etc/init.d/masq restart
signal-event fail2ban-conf

or

signal-event post-upgrade; signal-event reboot

	Warning:
	Failing to run either of these command will completly lock network access next time iptables rules are reloaded

DB command

there is no panel yet you can manage the contrib by the db configuration, it is quite simple

# config show fail2ban 
fail2ban=service
   Mail=enabled
   status=enabled

Available options are below:

• IgnoreIP: a comma separated list of IP or CIDR networks which will never be blocked by fail2ban. Exemple: 12.15.22.4,17.20.0.0/16. All your local networks and networks allowed to access the server-manager are already automatically whitelisted
• FilterLocalNetworks can be enabled or disabled (default is disabled). If set to enabled, local networks won't be whitelisted, and fail2ban can also ban hosts from the internal networks. Note that networks allowed to access the server-manager are not affected (they will never be blocked)
• BanTime: Duration (in seconds) of a ban. Default to 1800
• FindTime: The window fail2ban will check, in seconds. Default is 900. So, this mean fail2ban will only check for the number of failed login attempts in the last 15 minuts
• MaxRetry: Number of failed attempts in the last FindTime seconds to trigger a ban. Default is 3
• Mail: can be enabled or disabled (default is enabled). If enabled, each ban will be notified by mail
• MailRecipient: if Mail is enabled, the email address which should receive ban notifications. Default is root (the admin account will receive)

Use Fail2ban

List all jails

[root@sme8 ~]# fail2ban-client status 
Status
|- Number of jail:	10
`- Jail list:		http-overflows, http-noscript, http-auth, sogo, pam-generic, ssh-ddos, http-scan, ssh, qpsmtpd, recidive

List IP banned from a specific jail

[root@sme8 ~]# fail2ban-client status ssh

choose the specific jail with the command above which lists the Jail-list.

Play with a script which list How many ip are banned from all jails

nano /root/checklist_ban

#!/bin/bash
#lancer le script en sudo 
JAILS=$(fail2ban-client status | grep " Jail list:" | sed 's/`- Jail list:\t\t//g' | sed 's/,//g')
for j in $JAILS
do
echo "$j $(fail2ban-client status $j | grep " Currently banned:" | sed 's/   |- Currently banned:\t//g')"
done

chmod 700 /root/checklist_ban

to launch the script, do the following command:

/root/checklist_ban

Unban an IP

In certain case you would to unban an IP immediately because you don't want waste time to wait the automatic IP unban process of fail2ban. In first you you have to find the specific jail which has blocked you IP, you can refer to the mail that the admin user has received or you can list a specific jail.

fail2ban-client status qpsmtpd

Status for the jail: qpsmtpd
|- filter
|  |- File list:	/var/log/qpsmtpd/current /var/log/sqpsmtpd/current 
|  |- Currently failed:	5
|  `- Total failed:	119
`- action
   |- Currently banned:	1
   |  `- IP list:	93.17.128.20 
   `- Total banned:	1

If you want to know all you active jail, then do :

fail2ban-client status

Therefore you have to play with this command to unban your IP

fail2ban-client set qpsmtpd unbanip 93.17.128.20 

the generic command is :

fail2ban-client set JAIL unbanip MYIP

Jail.conf

The jail.conf is templated and the default file contains the configuration as below. You can add your own template of jail.conf at

/etc/e-smith/templates/etc/fail2ban/jail.conf

and do this to expland templates

expand-template /etc/rc.d/init.d/masq
/etc/init.d/masq restart
signal-event fail2ban-conf

default jail.conf

[DEFAULT]
ignoreip = 127.0.0.0/8 192.168.XXX.XXX 192.168.XXX.0/24
bantime  = 1800
findtime  = 900
maxretry = 3
usedns = yes
backend = auto

	Note:
	Your network and your server are in the list of ignored IP by fail2ban (see IgnoreIP)

[ssh]
enabled  = true
filter   = sshd
logpath  = /var/log/sshd/current
action   = smeserver-iptables[port="22",protocol=tcp,bantime=1800]
          smeserver-sendmail[name="SSH",dest=root]

[ssh-ddos]
enabled  = true
filter   = sshd-ddos
logpath  = /var/log/sshd/current
action   = smeserver-iptables[port="22",protocol=tcp,bantime=1800]
          smeserver-sendmail[name="SSH",dest=root]

[qpsmtpd]
enabled  = true
filter   = qpsmtpd
logpath  = /var/log/*qpsmtpd/current
maxretry = 9
action   = smeserver-iptables[port="25,465",protocol=tcp,bantime=1800]
          smeserver-sendmail[name="Qpsmtpd",dest=root]

[http-overflows]
enabled  = true
filter   = apache-overflows
logpath  = /var/log/httpd/error_log
action   = smeserver-iptables[port="80,443",protocol=tcp,bantime=1800]
          smeserver-sendmail[name="Apache (overflows)",dest=root]

[http-noscript]
enabled  = true
filter   = apache-noscript
logpath  = /var/log/httpd/error_log
action   = smeserver-iptables[port="80,443",protocol=tcp,bantime=1800]
          smeserver-sendmail[name="Apache (noscript)",dest=root]

[http-scan]
enabled  = true
filter   = apache-scan
logpath  = /var/log/httpd/error_log
action   = smeserver-iptables[port="80,443",protocol=tcp,bantime=1800]
          smeserver-sendmail[name="Apache (scan)",dest=root]

[http-auth]
enabled  = true
filter   = apache-auth
logpath  = /var/log/httpd/error_log
action   = smeserver-iptables[port="80,443",protocol=tcp,bantime=1800]
          smeserver-sendmail[name="Apache (auth)",dest=root]

[pam-generic]
enabled  = true
filter   = pam-generic
logpath  = /var/log/secure
maxretry = 6
action   = smeserver-iptables[bantime=1800]
          smeserver-sendmail[name="PAM generic",dest=root]

[recidive]
enabled  = true
filter   = recidive
logpath  = /var/log/fail2ban/daemon.log
bantime  = 604800
findtime = 86400
maxretry = 5
backend  = polling
action   = smeserver-iptables[bantime=604800]
          smeserver-sendmail[name="Recidive",dest=root]

Uninstall

yum remove smeserver-fail2ban

Bugs

Please raise bugs under the SME-Contribs section in bugzilla and select the smeserver-fail2ban component or use this link .