Sendmail slow?

[Smoot Carl-Mitchell]

On Sat, 2009-02-14 at 17:15 -0800, Knute Johnson wrote:
> Smoot Carl-Mitchell wrote:
> > You might try running strace on the listening SMTP process with timer
> > option to see where the delay is creeping in.  Something like
> > 
> > sudo strace -f -p <pid> -o <output_file> -t
> > 
> > You need the -f to pick up the forked processes as the listening
> > sendmail handles the connections.  The -t will give you timestamps on
> > each system call.
> 
> I sent the whole output but it was too big and rejected.  Anyway, this 
> shows a 5 second gap but I don't know what it really means.  If you can 
> decipher it, great!
> 
> Thanks,
> 

Here is the blow by blow.

Read /etc/resolv.conf.  Likely getting the names of your nameservers.
> 5092  17:05:19 stat64("/etc/resolv.conf", {st_mode=S_IFREG|0644, 
> st_size=91, ...}) = 0
> 5092  17:05:19 socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 5

Connect to 207.181.0.10 (would not happen to be one of your
nameservers?)  The connection descriptor is 5.
> 5092  17:05:19 connect(5, {sa_family=AF_INET, sin_port=htons(53), 
> sin_addr=inet_addr("207.181.0.10")}, 28) = 0
> 5092  17:05:19 poll([{fd=5, events=POLLOUT, revents=POLLOUT}], 1, 0) = 1

Send a request to descriptor 5.  This does look like a DNS request.
> 5092  17:05:19 send(5, 
> "\331S\1\0\0\1\0\0\0\0\0\0\6knute2\faerioconnect"..., 41, MSG_NOSIGNAL) = 41
> 5092  17:05:19 poll([{fd=5, events=POLLIN, revents=POLLIN}], 1, 5000) = 1
> 5092  17:05:19 ioctl(5, FIONREAD, [57]) = 0

Read the response.
> 5092  17:05:19 recvfrom(5, 
> "\331S\205\200\0\1\0\1\0\0\0\0\6knute2\faerioconnect"..., 1024, 0, 
> {sa_family=AF_INET, sin_port=htons(53), 
> sin_addr=inet_addr("207.181.0.10")}, [16]) = 57

Close the connection.
> 5092  17:05:19 close(5)                 = 0

Now set up a socket on port 587 which is the submit port. This is using
descriptor 8. What is host 216.240.58.140, BTW?
> 5092  17:05:19 getsockname(8, {sa_family=AF_INET, sin_port=htons(587), 
> sin_addr=inet_addr("216.240.58.140")}, [16]) = 0

Read /etc/services.
> 5092  17:05:19 open("/etc/services", O_RDONLY|0x80000 /* O_??? */) = 5
> 5092  17:05:19 fstat64(5, {st_mode=S_IFREG|0644, st_size=18449, ...}) = 0
> 5092  17:05:19 mmap2(NULL, 4096, PROT_READ|PROT_WRITE, 
> MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7ed6000
> 5092  17:05:19 read(5, "# Network services, Internet sty"..., 4096) = 4096
> 5092  17:05:19 close(5)                 = 0


> 5092  17:05:19 munmap(0xb7ed6000, 4096) = 0
> 5092  17:05:19 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
> 5092  17:05:19 rt_sigprocmask(SIG_BLOCK, [ALRM], [], 8) = 0
> 5092  17:05:19 time(NULL)               = 1234659919
> 5092  17:05:19 rt_sigaction(SIGALRM, {0xb7f9e170, [], SA_RESTART}, 
> {0xb7f9e170, [], SA_RESTART}, 8) = 0

Set an alarms for 5 seconds.
> 5092  17:05:19 alarm(5)                 = 0
> 5092  17:05:19 rt_sigprocmask(SIG_UNBLOCK, [ALRM], [ALRM], 8) = 0

New socket on descriptor 5.
> 5092  17:05:19 socket(PF_INET, SOCK_STREAM, IPPROTO_IP) = 5

Bind it to the address 216.240.58.140 which I assume is one of your
local interface addresses.
> 5092  17:05:19 bind(5, {sa_family=AF_INET, sin_port=htons(0), 
> sin_addr=inet_addr("216.240.58.140")}, 16) = 0

And connect on descriptor 5.  This is connecting on port 113 which
looking at /etc/services is the auth port. This trying to authenticate
the sender of the email using the AUTH protocol. See RFC1413.  Your
sendmail is trying to use AUTH to detemine the identity of the sender.
You can disable this in your sendmail.mc file by adding

define(`confTO_IDENT',    `0s')dnl

to your sendmail.mc and yor submit.mc file after the include for
debian-mta or debian-msp and redoing the make in /etc/mail.
 
> 5092  17:05:19 connect(5, {sa_family=AF_INET, sin_port=htons(113), 
> sin_addr=inet_addr("216.240.58.138")}, 16 <unfinished ...>


The alarm is triggered after 5 seconds which is the delay you are
seeing.  So the AUTH protocol is the source of the delay.
> 16288 17:05:24 <... select resumed> )   = 0 (Timeout)

-- 
Smoot Carl-Mitchell
Computer Systems and
Network Consultant
smoot at tic.com
+1 480 922 7313
cell: +1 602 421 9005