~ overflow ~

Problem:

How to test retrieve and send emails by raw telnet?

Solution:

Retrieving emails (bold lines are the commands, italics are outputs)

telnet mail.yourserver.com 110
Trying 1.2.3.4…
Connected to mail.yourserver.com.
Escape character is ‘^]’.
+OK Dovecot ready.
user your_email@yourserver.com
+OK
pass your_password
+OK Logged in.
list
+OK 1 messages:
1 1133

.

retr 1

message

.

quit

Sending emails:

telnet mail.youremailserver.com 25
Trying 1.2.3.4…
Connected to mail.youremailserver.com.
Escape character is ‘^]’.
220 youremailserver.com ESMTP Postfix
helo yourdomain.com
250 youremailserver.com
auth login
334 VXNlcm5hbWU6
eW91cmVtYWlsQHlvdXJkb21haW4uY29t (youremail@yourdomain.com base64 encoded)
334 UGFzc3dvcmQ6
eW91cnBhc3N3b3Jk (yourpassword base64 encoded)
235 2.0.0 Authentication successful
mail from:youremail@yourdomain.com
250 2.1.0 Ok
rcpt to: someone@somedomain.com
250 2.1.5 Ok
data
354 End data with <CR><LF>.<CR><LF>
subject: test

hi
.

250 2.0.0 Ok: queued as 8B65ED40075
quit
Note that there’s many different authentication protocols, base64 is the less secure one, some servers may require a better authentication mechanism, or even use an ecrypted port, which will not work with telnet, try open ssl instead.

Problem:

How to do a port scan on a specific ip/hostname on linux?

Solution:

nc -z <ip> <port-range>

eg.: nc -z 127.0.0.1 1-1024

Source:

ciberciti