port 25 can send/recieve outside but cant telnet from outside

robertkwild · 10-22-2015, 04:44 AM

hi all,

got a wierd problem, which i cant figure out

i CAN send and recieve emails from roundcube webmail to my gmail and vica versa, its on a vm which consists of postfix (SMTP)/dovecot (IMAP) and roundcube (webmail)

my postfix uses port 25 and i have enabled this through my pfsense firewall so it port forwards to my postfix server

so obviously it works as i can send recieve email from rouncube to my gmail and my friends hotmail, outlook accounts

but when i try to telnet to my postfix server ie telnet robina.ddns.net 25, it says connecting but it doesnt responed

can only one please help me on this

cheers,

rob

Skaperen · 10-22-2015, 04:50 AM

where you are telnetting FROM may have port 25 blocked. try telnetting to port 22 and see what happens. if you see "SSH" then just press return/enter.

descendant_command · 10-22-2015, 04:56 AM

From your telnet client machine, does robina.ddns.net resolve to your local server IP or your external IP?
If the latter, you won't be able to connect unless your router specifically supports NAT loopback.
You should use the hosts file or a local DNS server to provide correct local resolution or just telnet to the local name or IP.

robertkwild · 10-22-2015, 05:24 AM

mmm... but its wierd

if i change my postfix server to use port 587 and change my pfsense firewall NAT rule to the postfix server to use port 587 from my work pc i can telnet in to my postfix server at my home no problem

also this is the case if i change to use port 465 aswell

i will get the logs tonight when i get home

but it still doesnt explain why i can send/recieve from port 25 but cannot telnet into it

if i telnet port 25 it works internal but not external

descendant_command · 10-22-2015, 05:36 AM

Quote:

Originally Posted by Skaperen

where you are telnetting FROM may have port 25 blocked.

this

robertkwild · 10-22-2015, 06:47 AM

damn, they may block 25 out, i will check this out on my friends computer (as his router should allow all outbound) and get back to you guys

Emerson · 10-22-2015, 07:14 AM

http://www.canyouseeme.org/

Habitual · 10-22-2015, 07:18 AM

Code:

nmap 86.3.95.34 -p 25

Starting Nmap 6.40 ( http://nmap.org ) at 2015-10-22 08:18 EDT
Nmap scan report for cpc6-epso5-2-0-cust801.6-3.cable.virginm.net (86.3.95.34)
Host is up.
PORT   STATE    SERVICE VERSION
25/tcp filtered smtp

robertkwild · 10-24-2015, 11:49 AM

You were right, our companys firewall was blocking it so i downloaded a telent app for my mobile used 3g data and i could telent to my smtp server no probs