Here’s a collection of services, and ways to go about testing them:
25: SMTP
Simple Mail Transfer Protocol.
Test with telnet:
$ telnet simpleigh.com 25 Trying 46.137.167.228... Connected to simpleigh.com. Escape character is '^]'. 220 aws.simpleigh.com ESMTP Postfix (Ubuntu)
Check it responds:
$ EHLO example.com 250-aws.simpleigh.com 250-PIPELINING 250-SIZE 20480000 250-ETRN 250-STARTTLS 250-AUTH PLAIN LOGIN 250-AUTH=PLAIN LOGIN 250-ENHANCEDSTATUSCODES 250-8BITMIME 250 DSN
Try sending a message to a local user:
$ MAIL FROM: <nobody@example.com> 250 2.1.0 Ok $ RCPT TO: <blog@simpleigh.com> 250 2.1.5 Ok $ DATA 354 End data with <CR><LF>.<CR><LF> $ Email body goes here $ $ . $ 250 2.0.0 Ok: queued as 18E73288
Try logging in:
$ AUTH LOGIN 334 VXNlcm5hbWU6 $ [ base64-encoded username ] 334 UGFzc3dvcmQ6 $ [ base64-encoded password ] 235 2.7.0 Authentication successful
Exit:
$ QUIT 221 2.0.0 Bye Connection closed by foreign host.
You can test STARTTLS (where a secure channel is negotiated for an existing connection) functionality using OpenSSL‘s s_client:
$ openssl s_client -connect simpleigh.com:25 -crlf -starttls smtp ... loads of stuff 250 DSN $ EHLO ...
80: HTTP
Test with telnet:
$ telnet simpleigh.com 80 Trying 46.137.167.228... Connected to simpleigh.com. Escape character is '^]'. $ GET / HTTP/1.1 $ Host: simpleigh.com $ HTTP/1.1 301 Moved Permanently Date: Sun, 11 Aug 2013 19:54:30 GMT Server: Apache Location: http://www.simpleigh.com/ Vary: Accept-Encoding Content-Length: 233 Connection: close Content-Type: text/html; charset=iso-8859-1 <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"> <html><head> <title>301 Moved Permanently</title> </head><body> <h1>Moved Permanently</h1> <p>The document has moved <a href="http://www.simpleigh.com/">here</a>.</p> </body></html> Connection closed by foreign host.
110: POP3
Test with telnet:
$ telnet simpleigh.com 143 Trying 46.137.167.228... Connected to simpleigh.com. Escape character is '^]'. +OK Dovecot ready.
Try logging in:
$ USER [ username ] +OK $ PASS [ password ] +OK Logged in.
List messages:
$ LIST +OK 20 messages: ... loads of stuff
Exit:
$ QUIT DONE
143: IMAP
Internet Message Access Protocol.
Test with telnet:
$ telnet simpleigh.com 143 Trying 46.137.167.228... Connected to simpleigh.com. Escape character is '^]'. * OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE IDLE AUTH=PLAIN AUTH=LOGIN] Dovecot ready.
Try logging in:
$ a1 LOGIN [ username ] [ password ] a1 OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE IDLE SORT SORT=DISPLAY THREAD=REFERENCES THREAD=REFS MULTIAPPEND UNSELECT CHILDREN NAMESPACE UIDPLUS LIST-EXTENDED I18NLEVEL=1 CONDSTORE QRESYNC ESEARCH ESORT SEARCHRES WITHIN CONTEXT=SEARCH LIST-STATUS] Logged in
List folders:
$ a2 LIST "" "*" ... loads of stuff
Find out what’s in the Inbox:
$ a3 EXAMINE INBOX * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) * OK [PERMANENTFLAGS ()] Read-only mailbox. * 20 EXISTS * 1 RECENT * OK [UNSEEN 10] First unseen. * OK [UIDVALIDITY 1345668496] UIDs valid * OK [UIDNEXT 2543] Predicted next UID * OK [HIGHESTMODSEQ 1] Highest a3 OK [READ-ONLY] Select completed.
Exit:
$ a5 LOGOUT * BYE Logging out a5 OK Logout completed. closed
443: HTTPS
Just like HTTP, but use s_client:
$ openssl s_client -connect simpleigh.com:443 ... loads of stuff
465: SMTPS
Check using s_client:
$ openssl s_client -connect simpleigh.com:465 -crlf ... loads of stuff 220 aws.simpleigh.com ESMTP Postfix (Ubuntu)
993: IMAPS
Check using s_client:
$ openssl s_client -connect simpleigh.com:993 ... loads of stuff * OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE IDLE AUTH=PLAIN AUTH=LOGIN] Dovecot ready.
995: POP3S
Check using s_client:
$ openssl s_client -connect simpleigh.com:995 ... loads of stuff +OK Dovecot ready.
Summary
Almost everything can be driven via Telnet. If you need TLS, use s_client.
There’s a really handy OpenSSL command-line summary at http://www.madboa.com/geek/openssl/.