XPost: comp.os.linux.networking, comp.os.linux.misc   
   From: tauno.voipio@notused.fi.invalid   
      
   On 26.8.10 3:06 , Mark Hobley wrote:   
   > On Tue, 24 Aug 2010 09:50:56 +0000, Mark Hobley wrote:   
   >   
   >> I'm not sure how much of this is attributable to the Edimax unit, and   
   >> how much is due to a limitation of using Three Mobile as a provider.   
   >   
   >>> Someone more experienced will have to answer. I think your machine is   
   >>> not to blame, but it could be any other equipment between you and the   
   >>> SMTP server.   
   >   
   > I don't know where the fault lies, but after applying the following   
   > workaround, the reportbug tool no longer freezes:   
   >   
   > As root:   
   >   
   > echo 1>  /proc/sys/net/ipv4/ip_no_pmtu_disc   
   >   
   > Cheers,   
   >   
   > Mark.   
      
      
   This is not a very good idea. PMTU (Path Maximum Transfer Unit)   
   discovery finds how big TCP segment can be transferred without   
   IP fragmentation. It is one of the core operations in TCP.   
      
   Some guesses why this happens:   
      
   A) Some node in the path to the mail server has disabled ICMP   
       messages to prevent pings to the host (clueless security),   
      
   B) Your host uses ECN (Explicit Congestion Notification) but   
       the host at the other end does not understand it.   
      
   For controlling ECN, google for it. It is much less disturbing   
   to TCP to disable ECN than PMTU discovery.   
      
   --   
      
   Tauno Voipio   
   tauno voipio (at) iki fi   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)