on the yellowdog machine, you should see that the port number 3306 is open on all interfaces
netstat -an | grep 3306
should give a result with something like
tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN
this means that the computer is listening for any ip address to connect on to port 3306. also check and see if IPTABLES is running on that machine blocking that port.
iptables -L