I'm trying to debug a connection issue with network printer that is refusing to connect to a specific smtp server. While capturing from the same switch that the printer is connected to I can see packets coming up and down but, even smtp communication with "other smtp servers" but NOT to this particular one. the smtp server is alive as I can ping it and telnet it to port 25, and I can even send mails from email clients and all this will be visible with wireshark, not the failed connection to the problematic smtp.server4 I found that when the printer connect to the other smtp servers the packet length is 1514 so I suspected an mtu issue, but shouldn't I be able to see the the requests from mac source at least?
asked 31 Jan '12, 06:37
edited 31 Jan '12, 09:20
The real and deep reason why I couldn't see the specific smtp packets is still escaping to me, but it was solved hooking up an old hub instead of a switch.
answered 01 Feb '12, 07:03