Fail2ban named-refused jail not working resolution at arm’s length with these troubleshooting tips by our experts. 

At Bobcares, we offer solutions for every query, big and small, as a part of our Server Management Services.

Let’s take a look at how our Support Team helped our customers when Fail2ban named-refused jail not working.

How to fix: Fail2ban named-refused jail not working

Are you having trouble with fail2ban recently? One of our customers faced an issue where a jail called “named-refused” exists. Additionally, although the banned IPs make their way to the fail2ban.log file, these IPs are not actually blocked. Interestingly, the root cause behind this error is a missing expression in the named-denied filter to block IP.

Our Support Techs put together a solution to resolve the issue. It involves adding the following filter to the filter:

failregex = ^(?:view (?:internal|external): )?query(?: \(cache\))?

and commenting out the earlier rule “failregex = denied”. This will probably resolve the named-refused jail not working issue.

If the above solution does not help, our Support Techs have one more ace up their sleeve.

1. To begin with, check the fail2ban service is currently running without error by restarting it with the following command:

   systemctl restart fail2ban.service
2. Next, verify the jails are enabled with this command:

   fail2ban-client status

   This command will return the number of jails. If it returns 0, we have to enable the correct jails by going to jail.local file.

   For instance,

   #
   # SSH servers
   #
   
   [sshd]
   
   # To use more aggressive sshd modes set filter parameter "mode" in jail.local:
   # normal (default), ddos, extra or aggressive (combines all).
   # See "tests/files/logs/sshd" or "filter.d/sshd.conf" for usage example and details.
   #mode   = normal
   enabled = true
   mode    = aggressive
   port    = ssh
   logpath = %(sshd_log)s
   backend = %(sshd_backend)s

Let us know which troubleshooting tip helped resolved the Fail2ban named-refused jail not working issue at your end.

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Conclusion

In a nutshell, our skilled Support Engineers at Bobcares demonstrated two ways to solve Fail2ban named-refused jail not working issue.