fail2ban-client

Command

1. Comment

   The subprocess is immediately sent to the background, but fail2ban-client waits on a return code from the subprocess. The banip command will hang until the subprocess returns.
   Sudo

   This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.

   Remarks

   If there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....

   fail2ban-client add x
   fail2ban-client set x addaction x
   fail2ban-client set x action x actionban /path/to/command
   fail2ban-client start x
   fail2ban-client set x banip 999.999.999.999
   fail2ban-client set x unbanip 999.999.999.999
   fail2ban-client stop x

   Output

   The commands are executed but their output is hidden from the attacker.
2. Sudo

   This function is performed by the privileged user if executed via sudo because the acquired privileges are not dropped.

   Remarks

   If there are environment variables involved, they must be passed via sudo VAR=value ... or exported then sudo -E ....

   cat >/path/to/temp-dir/fail2ban.conf <<EOF
   [Definition]
   EOF
   
   cat >/path/to/temp-dir/jail.local <<EOF
   [x]
   enabled = true
   action = x
   EOF
   
   mkdir -p /path/to/temp-dir/action.d/
   cat >/path/to/temp-dir/action.d/x.conf <<EOF
   [Definition]
   actionstart = /path/to/command
   EOF
   
   mkdir -p /path/to/temp-dir/filter.d/
   cat >/path/to/temp-dir/filter.d/x.conf <<EOF
   [Definition]
   EOF
   
   fail2ban-client -c /path/to/temp-dir/ -v restart

   Output

   The commands are executed but their output is hidden from the attacker.