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 |
---|---|---|---|---|---|
309 | Develop | [c] 마우스 따라다니는 고양이 - 네코95 (WinAPI) | hooni | 2013.04.23 | 7945 |
308 | Develop | [c] 로또(Lotto) 번호 생성기 | hooni | 2013.04.23 | 7174 |
307 | Develop | [c] 레포트용으로 제출했던 여러 소스코드 모음 | hooni | 2003.04.23 | 8086 |
306 | Develop | [c] 라인수 입력받아 마름모꼴 출력하기.. | hooni | 2003.04.23 | 6869 |
305 | Develop | [c] 디피-헬만 키교환(Diffie–Hellman key exchange) 샘플 코드.. ㅋㄷ | hooni | 2013.04.23 | 9111 |
304 | Develop | [c] 도스 공격(DoS Attack) 프로그램 | hooni | 2013.04.23 | 11578 |
303 | Develop | [c] 도메인(호스트)으로 IP정보 알아오기.. (nslookup과 비슷) | hooni | 2013.04.23 | 6934 |
302 | Develop | [c] 도메인 소켓(Unix Domain Socket) UDP | hooni | 2013.04.23 | 9284 |
301 | Develop | [c] 더블(이중) 연결리스트 예제.. | hooni | 2013.04.23 | 7470 |
300 | Develop | [c] 달팽이 배열? 인지 먼지.. ㅋㅋ | hooni | 2013.04.23 | 7130 |
299 | Develop | [c] 단어 입력/수정 프로그램 소스 | hooni | 2003.04.23 | 7026 |
298 | Develop | [c] 단기과정[01/24] 정렬 알고리즘 | hooni | 2003.04.23 | 6955 |