So here's the problem, I can not download email from any external mail server. WBS one, no issues there. The first wierd part is sending (ala SMTP) is perfect, and secondly if the mail box is empty it works fine. If there is mail in the mail box it connects to the POP3 server and the timesout while downloading the email. The size does not matter (most emails I'm talking about are < 4k anyway).
It's not port related since I tried switching the port from 110 to 2001. It's also not mail server related since 3 seperate mail servers (one being Tiscali's/World Online) all show it. It's not email client related since I've tried Outlook, OE, and Thunderbird. It's not client machine/os related since I've tried it on 10 machines, which have three (more correctly 2 and a half) different OS's between them (WinXP, Win98, WinME) and on 2 different iBurst accounts at two different locations (~30km in between them).
The only constant in each setup is that there is a linux firewall (using IPTables to do the firewall). The linux box does nat'ting to the internal network as well. The linux box does not suffer from this problem itself, it can happily download email. Putting the iBurst direct on a workstations, and it works fine. Changing the IPTables rules to allow anything through (so just nat'ting going on) also does not work. This is only an iBurst problem, since connect via ADSL or Sentech and it works perfectly. Everything else works fine to the workstations (HTTP, Skype, FTP etc...), it's just the actual downloading of email. And the final bit of fun, is when I encrypt the POP3 (either SSH tunnel or SSL) it works perfectly in every setup.
What I am thinking is that the stateful packet inspection is somehow marking the packets or altering them, they hit the linux box (firewall) which can not understand how to correctly nat them so it drops them.
Any one got any ideas on how to get around this?
It's not port related since I tried switching the port from 110 to 2001. It's also not mail server related since 3 seperate mail servers (one being Tiscali's/World Online) all show it. It's not email client related since I've tried Outlook, OE, and Thunderbird. It's not client machine/os related since I've tried it on 10 machines, which have three (more correctly 2 and a half) different OS's between them (WinXP, Win98, WinME) and on 2 different iBurst accounts at two different locations (~30km in between them).
The only constant in each setup is that there is a linux firewall (using IPTables to do the firewall). The linux box does nat'ting to the internal network as well. The linux box does not suffer from this problem itself, it can happily download email. Putting the iBurst direct on a workstations, and it works fine. Changing the IPTables rules to allow anything through (so just nat'ting going on) also does not work. This is only an iBurst problem, since connect via ADSL or Sentech and it works perfectly. Everything else works fine to the workstations (HTTP, Skype, FTP etc...), it's just the actual downloading of email. And the final bit of fun, is when I encrypt the POP3 (either SSH tunnel or SSL) it works perfectly in every setup.
What I am thinking is that the stateful packet inspection is somehow marking the packets or altering them, they hit the linux box (firewall) which can not understand how to correctly nat them so it drops them.
Any one got any ideas on how to get around this?
I take it as a bit of a support desk excuse, but at this point I will try anything. Anyway the MTU is set to 1432 atm. Although thats on the ppp0 side, the ethernet port is still set to 1500. Wondering if I should change that as well?
