Installing and Configuring Fail2Ban on OmniOS
Fail2Ban is a program that will trigger actions based on patterns found in logs. I am setting up fail2ban to stop ssh brute forcing on my external ssh port. With the configuration below a user that fails to log in 5 times within 10 minutes will have all traffic to and from their IP blocked for 24 hours.
Fail2ban has been built in this repo, so let’s add it.
[email protected]:~# pkg set-publisher -g http://pkg.cs.umd.edu/ cs.umd.edu
The repo that we enabled above has fail2ban already built, so we can just install it with pkg.
[email protected]:~$ sudo pkg install fail2ban
Let’s edit the default configuration file to whitelist the local subnets and define a new rule. The new rule, called sshd-ipfilter will search the authlog for any failed logins and then block the rule with ipfilter. Edit the /ets/fail2ban/jail.conf file and add the following lines.
ignoreip = 127.0.0.1 192.168.5.0/24 10.0.1.0/24 ... [sshd-ipfilter] enabled = true filter = sshd action = ipfilter logpath = /var/log/authlog maxretry = 5 bantime = 84600 findtime = 600
We need to change the path in the ipfilter.conf so that it points to the correct ipf binary. The command below will update the file with the new path.
[email protected]:~$ sudo sed -i 's/\/sbin\/ipf/\/usr\/sbin\/ipf/' /etc/fail2ban/action.d/ipfilter.conf
The default configuration for syslog does not log the auth.info to the authlog. Luckily sshd logs to auth.info by default, so we can change the /etc/syslog.conf and add the following line.
After making the change to the syslog.conf file, we need to restart the system-log service.
[email protected]:/etc/fail2ban/action.d$ sudo svcadm restart system-log
The problem with the fail2ban pkg install is that it does not come with an SMF service. So we would either have to start it manually or write up a script to put in /etc/init.d. I went searching and found that someone else has already written the necessary files for SMF for fail2ban.
Let’s get the XML file.
[email protected]:/tmp$ wget https://github.com/fail2ban/fail2ban/raw/master/files/solaris-fail2ban.xml
There is one thing I want to change in the XML file. It has dependencies listed, but ipfilter is not one of them. Edit the solaris-fail2ban.xml file and add the following lines under the other dependencies. Note: if you want to change the user that fail2ban runs as, you can do that in this file.
<dependency name='net' grouping='require_all' restart_on='none' type='service'> <service_fmri value='svc:/network/ipfilter'></service_fmri> </dependency>
Let’s go a head and import the XML file.
[email protected]:/tmp$ sudo svccfg import solaris-fail2ban.xml
Now the second part of the service is the methods script. Let’s download that as well.
[email protected]:/tmp$ wget https://raw.github.com/fail2ban/fail2ban/master/files/solaris-svc-fail2ban
The script has different paths in it for the fail2ban binaries. We need to update it to look in /usr/bin.
[email protected]:/tmp$ sed -i 's/\/usr\/local\/bin\/fail2ban/\/usr\/bin\/fail2ban/g' solaris-svc-fail2ban
Now we can put it into place and change the permissions on it.
Let’s check the service definition and make sure that our dependencies list is there.
[email protected]:/tmp$ svcs -d fail2ban STATE STIME FMRI disabled 22:50:44 svc:/network/ipfilter:default online 22:50:46 svc:/network/loopback:default online 22:51:47 svc:/system/filesystem/local:default
It all looks good, so we can start the services.
I went ahead and made some invalid log in attempts to verify that the IPs would get blocked. Here is the line that is in the /var/log/fail2ban.log when it banned the IP.
2013-03-18 14:56:28,188 fail2ban.actions: WARNING [sshd-ipfilter] Ban 126.96.36.199
Below are the rules that fail2ban put in place for banning the IP.
[email protected]:/var/log$ sudo ipfstat -io ... block in quick from 188.8.131.52/32 to any
Everything works as we expected.
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