Best tool to use for port knocking into server?

sudo nmap -sS -T Polite -p22,1,2,3,4 x.x.x.x

Starting Nmap 6.25 ( http://nmap.org ) at 2013-03-08 05:44 CST
Note: Host seems down. If it is really up, but blocking our ping probes, try -Pn
Nmap done: 1 IP address (0 hosts up) scanned in 9.64 seconds
jason-danckss-macbook:~ Jason$ ssh root@x.x.x.x
ssh: connect to host x.x.x.x port 22: Operation timed out


I tried 2 port knocking utilities, thinking something was wrong with the first one then I installed knockd on debian server, same command, no luck, I'm thinking nmap is not the utility to be using.

/etc/knockd snippet:

[openSSH]
sequence = 22,1,2,3,4
seq_timeout = 5
command = /sbin/iptables -A INPUT -s %IP% -p tcp --dport 22 -j ACCEPT
tcpflags = syn


Should I change the config to look for UDP packets instead or something?