sudo fail2ban-client status
Inspect one jail:
sudo fail2ban-client status sshd
Unban an IP address from a specific jail:
sudo fail2ban-client set sshd unbanip 203.0.113.10
If you do not know which jail banned the address, check the fail2ban log:
sudo grep 203.0.113.10 /var/log/fail2ban.log