Tag Archives: linux

Technical

Knocking out multiple fail2ban notifications to admin

Ever since I’ve been troubleshooting and tweaking Fail2ban, it seems the ban notifications sent to the server admin email address has steadily increased. For example, a ban event currently sends 5 identical emails to the server admin.

I thought it was my limited understanding of how Fail2ban worked. But I soon realized that the culprit had to be multiple instances of Fail2ban causing the behavior. I had to dig up some Linux/Centos knowledge on how to figure out where to pull up processes (similar to the Windows services and task manager).

To show a master list of processes and pids:
ps aux || less

To display a list of pids with the name “fail2ban”:
pgrep fail2ban

To kill all pids with the name “fail2ban”:
pkill fail2ban

However, this kills all but one server instance of the Fail2ban server. I still had to start the server, reload the configuration and verify the status to ensure that it worked.

Remember to save and reload iptables prior to and after the above operations.

Technical

Killing stopped jobs

Sometimes I’ve had to CTRL-Z my way out of a Linux (Centos) command line that won’t work, accumulating a list of stopped jobs. This makes exiting impossible because the server will report that there are stopped jobs.

Use the following command line to get a list of stopped jobs:

jobs

Then by applying the following, the job can be killed and terminated right away without resorting to a process id number. Just enter the corresponding jobs number after the percent sign:

kill -9 %1

Once all the stopped jobs are killed, you can exit gracefully.