Solved: IP Communicator 7.0.6

tconnorbok · ‎03-19-2012

I am trying to get a users IP communicator to work but our firewalls guys are seeing our TFTP server getting blocked when it tries talking back on UDP port 1545. Does anyone know why it would be using this UDP port? I haven't found anything on the cisco site referencing this port and our firewall guys will not allow this port unless there is some documentation as to why.

Aaron Harrison · ‎03-19-2012

Hi

TFTP uses random ports. From http://en.wikipedia.org/wiki/Trivial_File_Transfer_Protocol:

... Data transfer is initiated on port 69, but the data transfer ports are chosen independently by the sender and receiver during initialization of the connection. The ports are chosen at random according to the parameters of the networking stack, typically from the range of Ephemeral ports.

Aaron

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!

View solution in original post

Aaron Harrison · ‎03-19-2012

Hi

TFTP uses random ports. From http://en.wikipedia.org/wiki/Trivial_File_Transfer_Protocol:

... Data transfer is initiated on port 69, but the data transfer ports are chosen independently by the sender and receiver during initialization of the connection. The ports are chosen at random according to the parameters of the networking stack, typically from the range of Ephemeral ports.

Aaron

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!

barry · ‎03-19-2012

Aaron has it (+5). Generally configuring application inspection on your firewall for the TFTP protocol (called a service policy on an ASA, other firewalls call it different things) will generally cause the firewall to automatically open the correct inbound ports.

HTH. Barry

Barry Hesk

Intrinsic Network Solutions