Network connection only transmits UDP?

  • a_mcleod

    a_mcleod - 2006-01-29

      I'm running coLinux under XP, and I have the TAP driver installed, and bridged to my Local Area Connection.  Inside coLinux, I can resolve domain names into IPs, but nothing else seems to work (this is why I suspect only UDP is getting through).  For instance, 'ping' returns:
    PING ( 56 data bytes

    ...And subsequently gets %100 packet loss.  On the Wiki's suggestion, I fiddled with the hardware checksumming switch on my NIC driver (3Com 3C940), but this didn't help.  I can ping coLinux from Windows, but not the other way around. 

      Does anyone have any ideas about how to fix this?  Do I need to specifically TELL the tap driver to send TCP packets or something? 



    • Ken Lux

      Ken Lux - 2006-01-30

      I would check winxp firewall settings.  I think there is a default not to respond to ICMP packets (which ping uses).  Can you try to access google trhough http (assuming you have Xvnc server running and KDE or Gnome windows managers installed).  You might also try nmap, as in:

      nmap -P0 -p80

      This will check to see if TCP port 80 is open on the host (-P0 does a stealth scan in that it doesn't use pings which in your case aren't getting though).

      I think that if you are getting domain name resolution, that you must have the gateway set up correctly.  If not, you might still be able to get domain name resolution from the xp machine.  In which case you could try

      nmap -P0

      where is your winxp IP address.  This should scan all common ports from 1-255.  You should see a few listed as open.

      If you can see ports, then it's just pings that are being blocked. You should be able to allow them through the ICMP settings on the Advanced tab of the Windows firewall settings.


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