This extension can be used if `--protocol icmp' is specified.  It
provides the following option:
.TP
.BR "--icmp-type " "[!] \fItypename\fP"
This allows specification of the ICMP type, which can be a numeric
ICMP type, or one of the ICMP type names shown by the command
.nf
 iptables -p icmp -h
.fi
