Comment 6 for bug 764933

typo, how do the printer report back?
There shouldn't be any problems if we know that.

It might be that ufw filters multicasts, which is shouldn't.

Try in one terminal window to run this "sudo tail -f /var/log/syslog' and then start hp-probe to discover your printer. That would to start some error reports showing up looking likt this:

[UFW BLOCK] IN=eth0 OUT= MAC= SRC=192.168.1.20 DST=239.255.255.250 LEN=122 TOS=0x00 PREC=0x00 TTL=1 ID=0 DF PROTO=UDP SPT=53194 DPT=1900 LEN=102

You can post only the ones comming from your printer here.