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 of your username and password. There are a couple ways to do this, the example below uses Perl:
perl -MMIME::Base64 -e 'print encode_base64("username");' perl -MMIME::Base64 -e 'print encode_base64("password");'
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:
telnet mailserver.com 25
Greet the mail server:
EHLO mailserver.com
Tell the server you want to authenticate with it:
AUTH LOGIN
The server should have returned 334 VXNlcm5hbWU6;
this is a base64 encoded string asking you for your username, paste the base64 encoded username you created earlier, example:
dXNlcm5hbWUuY29t
Now the server should have returned 334 UGFzc3dvcmQ6;
. Again this is a base64 encoded string now asking for your password, paste the base64 encoded password you created, example:
bXlwYXNzd29yZA==
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.
Below is a log of a real successful SMTP AUTH connection over Telnet:
user@localhost [~]# telnet exampledomain.com 25 Trying 1.1.1.1... Connected to exampledomain.com (1.1.1.1). Escape character is '^]'. 220-server1.exampledomain.com ESMTP Exim 4.66 #1 Wed, 09 May 2007 23:55:12 +0200 220-We do not authorize the use of this system to transport unsolicited, 220 and/or bulk e-mail. EHLO exampledomain.com 250-server1.exampledomain.com Hello [1.1.1.2] 250-SIZE 52428800 250-PIPELINING 250-AUTH PLAIN LOGIN 250-STARTTLS 250 HELP AUTH LOGIN 334 VXNlcm5hbWU6 dXNlcm5hbWUuY29t 334 UGFzc3dvcmQ6 bXlwYXNzd29yZA== 235 Authentication succeeded
번호 | 분류 | 제목 | 글쓴이 | 날짜 | 조회 수 |
---|---|---|---|---|---|
829 | Develop | [iphone] performSelector:withObject:afterDelay: 에 대한 내용 | hooni | 2013.04.23 | 65862 |
828 | Develop | [Android] 2010년에 만들었던 세미나 자료. | hooni | 2013.05.28 | 64659 |
827 | Develop | [c#] 간단한 IPC 통신 예제 | hooni | 2013.04.23 | 63722 |
826 | Develop | [vb] 비주얼 베이직 자격증용 ㅎㅎ | hooni | 2003.04.23 | 61356 |
825 | Develop | [android] Canvas를 이용해 이미지 확대/축소 하기 | hooni | 2013.04.23 | 60733 |
824 | Develop | [sh] 쉘스크립트 if 비교 연산 | hooni | 2020.05.26 | 59000 |
823 | Develop | [vb] 비주얼 베이직 141페이지 | hooni | 2003.04.23 | 58901 |
822 | Develop | [c#] Json 라이브러리 (System.Net.Json.dll) | hooni | 2013.04.23 | 58528 |
821 | Develop | [vb] 비주얼 베이직 순위 정렬 루틴 | hooni | 2003.04.23 | 58313 |
820 | Develop | [vb] 비주얼 베이직 131페이지 | hooni | 2003.04.23 | 58040 |
819 | Develop | 레고 NXT 마인드스톰 밸런싱 로봇 ㅎㅎ | hooni | 2013.04.23 | 57709 |
818 | Develop | [android] SurfaceView를 이용한 애니메이션 ㅎㅎ | hooni | 2013.04.23 | 57700 |