{"id":1755,"date":"2016-05-02T22:04:19","date_gmt":"2016-05-03T03:04:19","guid":{"rendered":"http:\/\/swildow.darktech.org\/wp\/?p=1755"},"modified":"2016-05-02T22:05:15","modified_gmt":"2016-05-03T03:05:15","slug":"how-to-test-smtp-auth-using-telnet","status":"publish","type":"post","link":"https:\/\/www.wildow.com\/blog\/?p=1755","title":{"rendered":"How to Test SMTP AUTH using Telnet"},"content":{"rendered":"

How to Test SMTP AUTH using Telnet<\/a><\/h1>\n
\n

Below are instructions on how to test SMTP<\/abbr> AUTH against a mail server using Telnet and entering the commands by hand.<\/p>\n

The first thing you need to do is get a base64 encoding of your username and password. There are a couple ways to do this, the example below uses Perl<\/abbr>:<\/p>\n

website to help with conversion:\u00a0 http:\/\/www.hcidata.info\/base64.htm<\/a><\/p>\n

@ symbol was messing with perl<\/p>\n

\n
\n
?<\/a><\/div>\n\n\n\n<\/tfoot>\n<\/table>\n<\/div>\n<\/div>\n

What will be returned from each command is a base64 encoding of the username and password; save these as you will need them later. Now connect to the mail server using Telnet:<\/p>\n

\n
1<\/div>\n
2<\/div>\n<\/td>\n
\n
\n
perl -MMIME::Base64 -e <\/code>'print encode_base64(\"username\");'<\/code><\/div>\n
perl -MMIME::Base64 -e <\/code>'print encode_base64(\"password\");'<\/code><\/div>\n<\/div>\n

\u00a0\u25b4<\/span><\/td>\n<\/tr>\n<\/thead>\n

\n\n\n<\/tfoot>\n<\/table>\n<\/div>\n<\/div>\n

Greet the mail server:<\/p>\n

\n
1<\/div>\n<\/td>\n
\n
\n
telnet mailserver.com 25<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/thead>\n
\n\n\n<\/tfoot>\n<\/table>\n<\/div>\n<\/div>\n

Tell the server you want to authenticate with it:<\/p>\n

\n
1<\/div>\n<\/td>\n
\n
\n
EHLO mailserver.com<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/thead>\n
\n\n\n<\/tfoot>\n<\/table>\n<\/div>\n<\/div>\n

The server should have returned 334 VXNlcm5hbWU6;<\/code> this is a base64 encoded string asking you for your username, paste the base64 encoded username you created earlier, example:<\/p>\n

\n
1<\/div>\n<\/td>\n
\n
\n
AUTH LOGIN<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/thead>\n
\n\n\n<\/tfoot>\n<\/table>\n<\/div>\n<\/div>\n

Now the server should have returned 334 UGFzc3dvcmQ6;<\/code>. Again this is a base64 encoded string now asking for your password, paste the base64 encoded password you created, example:<\/p>\n

\n
1<\/div>\n<\/td>\n
\n
\n
dXNlcm5hbWUuY29t<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/thead>\n
\n\n\n<\/tfoot>\n<\/table>\n<\/div>\n<\/div>\n

Now you should have received a message telling you that you successfully authenticated. If it failed your user\/pass may have been wrong or your mailserver is broken.<\/p>\n

Below is a log of a real successful SMTP<\/abbr> AUTH connection over Telnet:<\/p>\n

\n
1<\/div>\n<\/td>\n
\n
\n
bXlwYXNzd29yZA==<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/thead>\n
\n\n\n
\n
1<\/div>\n
2<\/div>\n
3<\/div>\n
4<\/div>\n
5<\/div>\n
6<\/div>\n
7<\/div>\n
8<\/div>\n
9<\/div>\n
10<\/div>\n
11<\/div>\n
12<\/div>\n
13<\/div>\n
14<\/div>\n
15<\/div>\n
16<\/div>\n
17<\/div>\n
18<\/div>\n
19<\/div>\n
20<\/div>\n
21<\/div>\n<\/td>\n
\n
\n
user@localhost [~]# telnet exampledomain.com 25<\/code><\/div>\n
Trying 1.1.1.1...<\/code><\/div>\n
Connected to exampledomain.com (1.1.1.1).<\/code><\/div>\n
Escape character is '^]'.<\/code><\/div>\n
220-server1.exampledomain.com ESMTP Exim 4.66 #1 Wed, 09 May 2007 23:55:12 +0200<\/code><\/div>\n
220-We do not authorize the use of this system to transport unsolicited,<\/code><\/div>\n
220 and\/or bulk e-mail.<\/code><\/div>\n
EHLO exampledomain.com<\/code><\/div>\n
250-server1.exampledomain.com Hello\u00a0 [1.1.1.2]<\/code><\/div>\n
250-SIZE 52428800<\/code><\/div>\n
250-PIPELINING<\/code><\/div>\n
250-AUTH PLAIN LOGIN<\/code><\/div>\n
250-STARTTLS<\/code><\/div>\n
250 HELP<\/code><\/div>\n
AUTH LOGIN<\/code><\/div>\n
334 VXNlcm5hbWU6<\/code><\/div>\n
dXNlcm5hbWUuY29t<\/code><\/div>\n
334 UGFzc3dvcmQ6<\/code><\/div>\n
bXlwYXNzd29yZA==<\/code><\/div>\n
<\/div>\n
235 Authentication succeeded<\/code><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/thead>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

How to Test SMTP AUTH using Telnet Below are instructions on how to test SMTP AUTH against a mail server using Telnet and entering the commands by hand. The first thing you need to do is get a base64 encoding … Read More »<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1755","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/www.wildow.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1755","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.wildow.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.wildow.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.wildow.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.wildow.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1755"}],"version-history":[{"count":2,"href":"https:\/\/www.wildow.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1755\/revisions"}],"predecessor-version":[{"id":1757,"href":"https:\/\/www.wildow.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1755\/revisions\/1757"}],"wp:attachment":[{"href":"https:\/\/www.wildow.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1755"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.wildow.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1755"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.wildow.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1755"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}