Проверка HTTP, SMTP по telnet

Почти у всех устройств в cli есть telnet клиент. С помощью него можно проверить доступность сервисов HTTP, SMTP и других.

HTTP

C2911-RND-INT#telnet 10.110.255.2 8080 /vrf TEST
Trying 10.110.255.2, 8080 ... Open
GET /index.htm HTTP/1.1
host: 10.110.255.2

HTTP/1.1 404 Not Found
Content-Type: text/html
Accept-Ranges: bytes
Server: HFS 2.2f

далее идёт html код.

SMTP

telnet mail.domain.ext 25

You should receive a reply like:

Trying ???.???.???.???...

Connected to mail.domain.ext.

Escape character is '^]'.

220 mail.domain.ext ESMTP Sendmail ?version-number?; ?date+time+gmtoffset?

You will then need to delcare where you are sending the email from:

HELO local.domain.name - dont worry too much about your local domain name although you really should use your exact fully qualified domain name as seen by the outside world the mail server has no choice but to take your word for it as of RFC822-RFC1123.

This should give you:

250 mail.domain.ext Hello local.domain.name [loc.al.i.p], pleased to meet you

Now give your email address:

(On many mailservers the space after the : is required rather that optional. Thanks to Justing Goldberg)

MAIL FROM: mail@domain.ext

Should yeild:

250 2.1.0 mail@domain.ext... Sender ok

If it doesn't please see possible problems.

Now give the recipients address:

RCPT TO: mail@otherdomain.ext

Should yeild:

250 2.1.0 mail@otherdomain.ext... Recipient ok

If it doesn't please see possible problems.

To start composing the message issue the command DATA

If you want a subject for your email type Subject:-type subject here- then press enter twice (these are needed to conform to RFC 882)

You may now proceed to type the body of your message (e.g. hello mail@otherdomain.ext from mail@domain.ext)

To tell the mail server that you have completed the message enter a single "." on a line on it's own.

The mail server should reply with: 250 2.0.0 ???????? Message accepted for delivery

You can close the connection by issuing the QUIT command.

The mailserver should reply with something like:221 2.0.0 mail.domain.ext closing connection

Connection closed by foreign host.