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 |
---|---|---|---|---|---|
757 | Develop | [ios] 동영상 플레이어 샘플 (for Local File) | hooni | 2017.02.07 | 1215 |
756 | Develop | [ios] FlckrFeed Example App (Swift) | hooni | 2016.11.27 | 1215 |
755 | Develop | [ios] UIView 계층구조 | hooni | 2015.01.03 | 1231 |
754 | Develop | [maven] Mac OS에 메이븐(maven) 설치하기 | hooni | 2015.01.21 | 1233 |
753 | Develop | [ubuntu] 우분투 18.04에 PHP5 설치하기 | hooni | 2020.11.14 | 1244 |
752 | Develop | [ios] Objective-C Types & Storage Capacity | hooni | 2015.07.22 | 1264 |
751 | Develop | GPL, AGPL, MPL,.. 한눈에 보는 오픈소스SW 라이선스 | hooni | 2014.10.14 | 1273 |
750 | Develop | [ios] 코코아 프로그래밍의 네이밍 룰(명명 규칙) | hooni | 2017.05.11 | 1296 |
749 | Develop | [coding] Find all anagrams in a string | hooni | 2017.06.27 | 1306 |
748 | Develop | [js] Click button copy to clipboard | hooni | 2018.04.05 | 1308 |
747 | Develop | [ios] NavigationController 에서 왼쪽(back) 버튼 후킹하기 | hooni | 2015.10.23 | 1308 |
746 | Develop | [android] Calling activity function from separate class | hooni | 2016.11.15 | 1319 |