UDP and firewall problem

Hello. I am currently developing a test chat application. I send data using UDP. Will it be a problem if user is behind a firewall?
[138 byte] By [mastertaoa] at [2007-10-3 2:58:11]
# 1
Like all other network traffic you need to let the port of the receiving client to be opened. Or you can of course use a tunnel.
emeratiusa at 2007-7-14 20:47:36 > top of Java-index,Core,Core APIs...