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In attempt to understand PAT, I've setup the following setup where I have a Linux Router that masquerades from in internal interface to the external. Thus both clients are able to talk to outside Server with IP translation happening in the Linux Router PC.

  +---------------+
  | client 1      |
  | src port 4567 |--+
  +---------------+  | +--------+     +--------------+
                     +-| Linux  |-----| Server listen|
                     +-| Router |     | on port 9584 |
  +---------------+  | +--------+     +--------------+
  | client 2      |  |
  | src port 4567 |--+
  +---------------+

I did a simple echo call using nc from client 1 and client 2 to Server PC and noticed the source port of the packet was in fact 4567. When I ran the nc with the same src port number from both clients, one connection cause the other to break! (The clients are different computers btw) so I had the assumption that iproute hides the port number too and does some translation much like IP mapping. Is this problem fixable?

ArmenB
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  • If you take the router out of the picture do you see the same behavior for your netcat connections? – Zoredache Aug 26 '13 at 16:59
  • I'm in a company network and the `src port` number gets changed on the way out. I say this because I do `tcpdump` on the server computer and I visually see that the `port` number is not `4567`. – ArmenB Aug 26 '13 at 17:01

0 Answers0