-----Original Message----- From: cour...@lists.sourceforge.net [mailto:cour...@lists.sourceforge.net]On Behalf Of John Belmonte Sent: Wednesday, December 10, 2003 9:32 AM To: cour...@lists.sourceforge.net Subject: [courier-users] connection to courier SMTP server from certain machines has long delay

Hello,

I'm using Courier 0.42.2. My email client was showing a symptom of a long delay (30-40 seconds) when connecting to a Courier SMTP server. I've tracked this delay down to the SMTP server. If you just telnet to the server, the delay happens between the initial connection and when the server sends the "220 machine.example.net ESMTP" message. The puzzling thing is that the delay only occurs when I telnet from my local network. Testing from two locations outside my network, there is no delay. The only difference I notice is that the address of my local network is not ping-able from the internet, while the other locations I tested are.

I've compared the strace output of the SMTP server for the two cases. In the bad case, some connection attempt is timing out. In the good case, that connection attempt is being refused immediately. Anyone know what's going on?

=== Bad case ===

[pid 15290] getsockname(6, {sin_family=AF_INET6, sin6_port=htons(587), inet_pton(AF_INET6, "::ffff:212.13.199.71", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, [28]) = 0 [pid 15290] socket(PF_INET6, SOCK_STREAM, 0) = 7 [pid 15290] bind(7, {sin_family=AF_INET6, sin6_port=htons(0), inet_pton(AF_INET6, "::ffff:212.13.199.71", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = 0 [pid 15290] time([1071075593]) = 1071075593 [pid 15290] fcntl64(7, F_SETFL, O_RDONLY|O_NONBLOCK) = 0 [pid 15290] connect(7, {sin_family=AF_INET6, sin6_port=htons(113), inet_pton(AF_INET6, "::ffff:64.185.132.156", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = -1 EINPROGRESS (Operation now in progress) *** LONG DELAY HERE *** [pid 15290] select(8, NULL, [7], NULL, {30, 0}) = 0 (Timeout) [pid 15290] close(7) = 0 [pid 15290] open("/etc/resolv.conf", O_RDONLY) = 7 . . .

=== Good case ===

[pid 15443] getsockname(6, {sin_family=AF_INET6, sin6_port=htons(587), inet_pton(AF_INET6, "::ffff:212.13.199.71", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, [28]) = 0 [pid 15443] socket(PF_INET6, SOCK_STREAM, 0) = 7 [pid 15443] bind(7, {sin_family=AF_INET6, sin6_port=htons(0), inet_pton(AF_INET6, "::ffff:212.13.199.71", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = 0 [pid 15443] time([1071076240]) = 1071076240 [pid 15443] fcntl64(7, F_SETFL, O_RDONLY|O_NONBLOCK) = 0 [pid 15443] connect(7, {sin_family=AF_INET6, sin6_port=htons(113), inet_pton(AF_INET6, "::ffff:192.17.3.4", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = -1 EINPROGRESS (Operation now in progress) [pid 15443] select(8, NULL, [7], NULL, {30, 0}) = 1 (out [7], left {29, 903810}) [pid 15443] connect(7, {sin_family=AF_INET6, sin6_port=htons(113), inet_pton(AF_INET6, "::ffff:192.17.3.4", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = -1 ECONNREFUSED (Connection refused) [pid 15443] close(7) = 0 [pid 15443] open("/etc/resolv.conf", O_RDONLY) = 7 . . .