Hi Tapani Tarvainen, I got your modification working only when telnet gives a prompt, something like,
kuria...@debian:~$ telnet 192.168.0.20 25 Trying 192.168.0.20... Connected to 192.168.0.20. Escape character is '^]'. 220 rhel.virusk.org ESMTP Sendmail 8.13.8/8.13.8; Tue, 14 Apr 2009 22:34:26 +0530 But, when this server has a firewall block, then, kuria...@debian:~$ telnet 192.168.0.20 25 Trying 192.168.0.20... So, it didn't bring us to the telnet prompt and I think, it works only when telnet is successful and gives a prompt. Do advice. Regards, Kurian Thayil. On Thu, 2009-04-16 at 08:19 +0300, Tapani Tarvainen wrote: > You could abort the telnet using its escape sequence instead of > using smtp quit, i.e., > > #! /bin/bash > case "$( (sleep 5; echo -e '\033q') | telnet 192.168.0.20 25 2>&- )" > in > *' > 220 '*) echo Success ;; > *) echo Failed ;; > esac > > If you want to be friendly to the mail server you could do both: > > case "$( (sleep 5; echo quit; sleep 5; echo -e '\033q') | telnet > 192.168.0.20 25 2>&- )" in > > That will look a bit nicer in the mail server logs and may avoid > tripping some spam/attack detection tools. > > Also, you may need to adjust the delays: the time a mail server > takes to respond to initial connection may vary a lot, > depending on things like its load and whatnot. > Quite a few even deliberately wait some 10 seconds just > to trip spamming software known to be too impatient. -- Kurian Mathew Thayil. (GPG KeyID: E232394F)
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