Ugo Bellavance wrote:

Brett Schroeder wrote:

...

Ugo Bellavance wrote:

...

Hi,

I installed sendmail on a centos-4 openvz VM.  I set up SMTP-AUTH

and when I try to send mail using this server, there is a big delay in which my e-mail client (Mozilla Thunderbird) just hangs. The server, on the other hand, is idle at the same time. It does that no matter if I use no encryption, TLS, or SSL. When the client is 'hung' sendmail, on the server side haven't logged anything yet for this connection.

Any idea?

Since nothing is logged on the server, it sounds like there is a firewall (or other networking problem) in the way. You should use WireShark (or tcpdump) on the client to capture the network traffic.

I disabled the firewall on the server, no luck. I tried sniffing, I see nothing weird.

5.512292 74.59.221.180 -> 72.55.149.51 TCP 17274 > submission [PSH, ACK] Seq=350 Ack=10923 Win=17461 Len=53 5.512984 72.55.149.51 -> 74.59.221.180 TCP submission > 17274 [PSH, ACK] Seq=10923 Ack=403 Win=7504 Len=277 5.724172 74.59.221.180 -> 72.55.149.51 TCP 17274 > submission [ACK] Seq=403 Ack=11200 Win=17184 Len=0 22.884013 74.59.221.180 -> 72.55.149.51 TCP 17274 > submission [PSH, ACK] Seq=403 Ack=11200 Win=17184 Len=53 22.884918 72.55.149.51 -> 74.59.221.180 TCP submission > 17274 [PSH, ACK] Seq=11200 Ack=456 Win=7504 Len=85 22.970714 74.59.221.180 -> 72.55.149.51 TLSv1 Application Data 22.971120 72.55.149.51 -> 74.59.221.180 TLSv1 Application Data

(I removed all lines containing SSH or ssh).

Thanks,

Ugo

Ray Van Dolson wrote:

On Wed, Jul 25, 2007 at 07:35:58PM -0400, Ugo Bellavance wrote:

...

Ugo Bellavance wrote:

...

Brett Schroeder wrote:

...

Ugo Bellavance wrote:

...

Hi,

I installed sendmail on a centos-4 openvz VM. I set up SMTP-AUTH and when I try to send mail using this server, there is a big delay in which my e-mail client (Mozilla Thunderbird) just hangs. The server, on the other hand, is idle at the same time. It does that no matter if I use no encryption, TLS, or SSL. When the client is 'hung' sendmail, on the server side haven't logged anything yet for this connection.

Any idea?

Since nothing is logged on the server, it sounds like there is a firewall (or other networking problem) in the way. You should use WireShark (or tcpdump) on the client to capture the network traffic.

I disabled the firewall on the server, no luck. I tried sniffing, I see nothing weird.

5.512292 74.59.221.180 -> 72.55.149.51 TCP 17274 > submission [PSH, ACK] Seq=350 Ack=10923 Win=17461 Len=53 5.512984 72.55.149.51 -> 74.59.221.180 TCP submission > 17274 [PSH, ACK] Seq=10923 Ack=403 Win=7504 Len=277 5.724172 74.59.221.180 -> 72.55.149.51 TCP 17274 > submission [ACK] Seq=403 Ack=11200 Win=17184 Len=0 22.884013 74.59.221.180 -> 72.55.149.51 TCP 17274 > submission [PSH, ACK] Seq=403 Ack=11200 Win=17184 Len=53 22.884918 72.55.149.51 -> 74.59.221.180 TCP submission > 17274 [PSH, ACK] Seq=11200 Ack=456 Win=7504 Len=85 22.970714 74.59.221.180 -> 72.55.149.51 TLSv1 Application Data 22.971120 72.55.149.51 -> 74.59.221.180 TLSv1 Application Data

Can you run strace on sendmail during a connection and see what it's doing? DNS is often the culprit when delays are concerned, so look for anything along those lines.

Ray

Here is an interesting part, but I can't tell why it took 2.292863 seconds to do that:

09:07:47 time(NULL) = 1185455267 <0.000007> 09:07:47 rt_sigprocmask(SIG_UNBLOCK, [ALRM], [ALRM], 8) = 0 <0.000008> 09:07:47 select(8, [4 5 6 7], NULL, NULL, {5, 0}) = 1 (in [6], left {2, 707000}) <2.292863> 09:07:49 accept(6, {sa_family=AF_INET, sin_port=htons(25919), sin_addr=inet_addr("74.59.221.180")}, [16]) = 9 <0.000023> 09:07:49 rt_sigprocmask(SIG_BLOCK, [ALRM], [], 8) = 0 <0.000010> 09:07:49 time(NULL) = 1185455269 <0.000007> 09:07:49 pipe([10, 11]) = 0 <0.000021> 09:07:49 rt_sigprocmask(SIG_BLOCK, [CHLD], [ALRM], 8) = 0 <0.000008> 09:07:49 clone(Process 16312 attached

Some operations are unfinished like this one:

[pid 31853] 09:07:49 select(8, [4 5 6 7], NULL, NULL, {5, 0} <unfinished ...>

There is a 5-second gap here (from one PID to the other, weird):

[pid 16312] 09:07:49 time(NULL) = 1185455269 <0.000010> [pid 16312] 09:07:49 read(9, 0x8968260, 5) = -1 EAGAIN (Resource temporarily unavailable) <0.000012> [pid 16312] 09:07:49 time(NULL) = 1185455269 <0.000009> [pid 16312] 09:07:49 select(10, [9], NULL, [9], {3600, 0} <unfinished ...> [pid 31853] 09:07:54 <... select resumed> ) = 0 (Timeout) <4.999631> [pid 31853] 09:07:54 rt_sigprocmask(SIG_BLOCK, [ALRM], [], 8) = 0 <0.000008> [pid 31853] 09:07:54 time(NULL) = 1185455274 <0.000008> [pid 31853] 09:07:54 open("/proc/loadavg", O_RDONLY) = 9 <0.000037> [pid 31853] 09:07:54 fstat64(9, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0 <0.000008> [pid 31853] 09:07:54 read(9, "0.01 0.02 0.00 3/49 16395\n", 1024) = 26 <0.000015> [pid 31853] 09:07:54 close(9) = 0 <0.000013> [pid 31853] 09:07:54 time(NULL) = 1185455274 <0.000007> [pid 31853] 09:07:54 open("/proc/loadavg", O_RDONLY) = 9 <0.000015>