Testing SMTP-AUTH from the command line

I’m building a new pair of ‘mail-relay’ servers for customers to mail out through. Customers can only use SMTP-AUTH to send mail, but i needed a method of testing the mechanism. Actually I’ll be using MySQL based usernames and passwords, but before I get stuck into pam-mysql i needed to test it was working on system accounts. To test you need to base64 encode the username and password to submit them via the command line. Ive added an account allied ‘mutest’ with a password of ‘mytest99’ to demonstrate. Don’t’t worry, the account has now been deleted! First job is to get the encoded hashes for which we use a command line perl script.

# perl -MMIME::Base64 -e 'print encode_base64("mytest")'
bXl0ZXN0
# perl -MMIME::Base64 -e 'print encode_base64("mytest99")'
bXl0ZXN0OTk=

Ok thats the hashing done, now we can test the SMTP-AUTH system.

# telnet 127.0.0.1 25
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 mailout1.gconnect.net ESMTP Mail Service; Wed, 4 Jan 2012 12:41:44 GMT
ehlo gconnect.net
250-mailout1.gconnect.net Hello localhost [127.0.0.1], pleased to meet you
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-EXPN
250-VERB
250-8BITMIME
250-SIZE 30000000
250-DSN
250-ETRN
250-AUTH LOGIN PLAIN
250-DELIVERBY
250 HELP
auth login
334 VXNlcm5hbWU6
bXl0ZXN0
334 UGFzc3dvcmQ6
bXl0ZXN0OTk=
235 2.0.0 OK Authenticated

So thats a success! Although we need to test a failure too, so i’ll make a new hash of the wrong password:

# perl -MMIME::Base64 -e 'print encode_base64("mytest98")'
bXl0ZXN0OTg=

Now i’ll do it all again with the incorrect password.

[root@mailout1 ~]# telnet 127.0.0.1 25
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 mailout1.gconnect.net ESMTP Mail Service; Wed, 4 Jan 2012 12:45:40 GMT
ehlo gconnect.net
250-mailout1.gconnect.net Hello localhost [127.0.0.1], pleased to meet you
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-EXPN
250-VERB
250-8BITMIME
250-SIZE 30000000
250-DSN
250-ETRN
250-AUTH LOGIN PLAIN
250-DELIVERBY
250 HELP
auth login
334 VXNlcm5hbWU6
bXl0ZXN0
334 UGFzc3dvcmQ6
bXl0ZXN0OTg=
535 5.7.0 authentication failed

Pretty straightforward, but not something we do every day.

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