Thanks @dbrgn, support for `esp` and `ah` added in ca2ab4c. 

@bendiken iptables (and ufw) works on transport layer (tcp, udp) and Internet layer (ip, ipsec) protocols. /etc/services actually maps well-known service names to tcp/udp ports, as explained in the [man page](http://manpages.ubuntu.com/manpages/precise/man5/services.5.html).