Fail2Ban is great but sometimes you ban wrongly.
Here's how to unban an IP banned by Fail2Ban.
Log to server as root.
List the banned ip with the command:
> iptables -L
You'll get something like:
... Chain fail2ban-apache-botseeker-adf (1 references) target prot opt source destination DROP all -- APoitiers-551-1-48-250.w92-146.abo.wanadoo.fr anywhere DROP all -- ip-83-134-25-126.dsl.scarlet.be anywhere DROP all -- ADijon-154-1-14-132.w90-33.abo.wanadoo.fr anywhere DROP all -- cnv94-6-88-185-61-237.fbx.proxad.net anywhere DROP all -- mau78-1-88-184-109-30.fbx.proxad.net anywhere DROP all -- APlessis-Bouchard-154-1-33-207.w90-3.abo.wanadoo.fr anywhere DROP all -- crawl-66-249-68-133.googlebot.com anywhere DROP all -- ABordeaux-257-1-85-192.w90-50.abo.wanadoo.fr anywhere DROP all -- 220.127.116.11.rev.sfr.net anywhere DROP all -- ANancy-256-1-30-55.w90-26.abo.wanadoo.fr anywhere DROP all -- AAnnecy-158-1-62-25.w90-48.abo.wanadoo.fr anywhere DROP all -- ALagny-152-1-28-44.w83-112.abo.wanadoo.fr anywhere DROP all -- pub30-175.mobius.fr anywhere DROP all -- APuteaux-651-1-273-223.w90-44.abo.wanadoo.fr anywhere DROP all -- 81-67-122-188.rev.numericable.fr anywhere DROP all -- 18.104.22.168.rev.sfr.net anywhere DROP all -- 22.214.171.124.rev.sfr.net anywhere DROP all -- crawl-66-249-71-209.googlebot.com anywhere RETURN all -- anywhere anywhere ...
We can see on the penultimate line that Fail2Ban banned the crawler from Google, just that. I don't know about you, but it's not a target I was planning to ban.
You have to count the number of IP lines banned up to the one you want to unban. This is the 18th line.
Then a small command line, you will of course have to replace “fail2ban-apache-botseeker-adf” by the name of the filter that banned the ip and “18" by the corresponding line number.
> iptables -D fail2ban-apache-botseeker-adf 18
Restart the first command to verify that the IP is no longer in the list of banned addresses.
If like me, you have implemented a ban strategy based on Apache error logs to avoid robots, consider monitoring Fail2Ban with a tool like Munin or Cacti and checking from time to time who you have banned.