This mail is from: From: "Hostmaster methusalix.net" <[EMAIL PROTECTED]>
Hostmaster methusalix.net wrote: > Hi there, > > since the last days I am examining a strange problem while connecting to a > SMTP server which does not show the banner. At first I thought it is a > problem with exim from testing but after testing with telnet from several > different boxes, I noticed that the problem seems to be more deeper. And > by the way it has nothing to do with DNS oder ident problems. It is only > this single server to now, which makes trouble. > Telneting from non-debian boxes works. If trying to connect from a > debian box, tcpdump output looks like this: > > 15:36:18.330348 me.1413 > them.smtp: S 227803692:227803692(0) win 16060 <mss > 1460,sackOK,timestamp 69383157 0,nop,wscale 0> (DF) [tos 0x10] > 15:36:18.380285 them.smtp > me.1413: S 905637469:905637469(0) ack 227803693 > win 30660 <mss 1460,sackOK,timestamp 140675877 69383157,nop,wscale 0> [tos > 0x60] > 15:36:18.380326 me.1413 > them.smtp: . ack 1 win 16060 <nop,nop,timestamp > 69383162 140675877> (DF) [tos 0x10] > 15:36:21.795097 them.smtp > me.1413: S 905637469:905637469(0) ack 227803693 > win 30660 <mss 1460,sackOK,timestamp 140676220 69383157,nop,wscale 0> [tos > 0x60] > 15:36:28.231108 me.1413 > them.smtp: P 1:7(6) ack 1 win 16060 > <nop,nop,timestamp 69384147 140676220> (DF) [tos 0x10] > 15:36:28.257714 them.smtp > me.1413: . ack 7 win 30660 <nop,nop,timestamp > 140676867 69384147> [tos 0x60] > > while the last lines repeats after some time. > > Comparing the dump with a non-debian box shows, that the second to last line > is repeated after a short time and then the communication works. I'm not a > tcp expert, but for me it looks like the other SMTP server is waiting for > something and repeats its requests. Sending HELO without waiting for the > banner works by the way and I can send mail by hand via telnet. > > My current guess is, that it maybe has something to do with the kernel or > with its configuration. Until now, there are no ipchains rules and all > /proc/sys/net/ipv4 settings are the default from potato. > I'm using 2.2.19 and the other side runs straight-out-the box SuSe 7.0. > They said, they had already some SMTP problems with other hosts, but they > fixed it with a newer Sendmail version which is now at 8.10. > > Hope someone understands this :o) > > jps -- Crap can work. Given enough thrust pigs will fly, but it's not necessary a good idea.
