On 2011-02-24 13:09, Wietse Venema wrote: > Stanisław Findeisen: >> Hi >> >> I am getting such errors in the log: >> >> Feb 24 10:03:21 * postfix/smtp[9203]: C2EFF1823C1: lost connection with >> ASPMX.L.GOOGLE.COM[74.125.43.27] while sending end of data -- message >> may be sent more than once >> >> This happens many times a day with various servers --- not just >> google.com. Otherwise everything works fine. >> >> What do you think the problem is? > > Don't speculate, measure. Look at packet traces with tcpdump, > and see at what point the connection breaks. > > - Does the problem only happen with connections that use TCP window > scaling? If so, you have a borked firewall that mis-implements TCP. > > - Does the problem go away with small messages? If so, you have a > broken IP path MTU problem. > > And so on, there are many reasons why TCP can break. > > Wietse
Thank you, Wietse. Indeed the problem was with too big (1500) IPv4 packets going out. It is not clear yet why is the MTU calculation broken. Some hop must really be broken there, because there is DF flag set on outgoing IPv4 packets and we're not getting any ICMP Fragmentation Needed back (we're just getting nothing). Anyway this doesn't seem to be Postfix related. -- Eisenbits - proven software solutions: http://www.eisenbits.com/ OpenPGP: DFD9 0146 3794 9CF6 17EA D63F DBF5 8AA8 3B31 FE8A
signature.asc
Description: OpenPGP digital signature
