IPTABLES

iptables -nvL --line-number # show rules with line number
iptables -nvL -t nat --line-number # show rules with line number for NAT table
iptables -nvL -t mangle --line-number # show rules with line number for MANGLE table
iptables -S # show source command of rules

chain

iptables -L $CHAIN -v -n --line-numbers # list rules for chain $CHAIN
iptables -D $CHAIN $LINE_NUMBER # delete rule $LINE_NUMBER for chain $CHAIN
iptables -t $TABLE -D $CHAIN $LINE_NUMBER # delete rule $LINE_NUMBER for chain $CHAIN and specific table

FAIL2BAN

fail2ban client

fail2ban-client status # get global status
fail2ban-client status $jail # get ssh status
fail2ban-client get loglevel # get log level
fail2ban-client get setlogvel $level # set level for log
fail2ban-client get $jail ignoreip # get ignore ip for $jail
fail2ban-client set $jail addignoreip IP # add ignore ip IP for $jail