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SilverLight
Asked: 2011-09-04 01:54:15 +0800 CST

how fix telnet at port 25 or 110 or 143 connection failed?

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I installed third party application on my Windows 2008 server to turn it into a mail server (MDaemon)...
I filled the info during its wizard very carefully without any changes in its options or preferences!
I configured it's IIS to use webAdmin and webClient and every thing is ok about them...
also this server acts as a web server (IIS and DNS are installed).

I turned my server and my pc firewall off...(both firewalls are node 32)

Executing these commands on the server are ok : 

telnet ip-address of server(127.0.0.1 on server) 25  
telnet ip-address of server(127.0.0.1 on server) 110  
telnet ip-address of server(127.0.0.1 on server) 143

but those commands fail on my local machine far away from that server!
What does that mean and what can I do to fix that?
I am system web developer , so I would appreciate some explanation about this situation!

windows-server-2008 email-server telnet

3 Answers

  1. Best Answer

    If you are running into the failed connection attempts from a remote system, then the firewall on the server may require configuration for those ports.

    If the failed connection attempts are occurring while on the server itself (via 127.0.0.1), then the server services themselves may not be running.

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  2. If I read the description correctly, you can telnet to the ports ON the server (locally) without a problem, but your remote machine can't get to the ports.

    That would imply that there is a firewall blocking the connection or the ports are not configured for machines outside localhost to connect to them.

    To see if the ports are open at all, you can run a portscanner like Nmap from your remote machine to the server to see what ports are showing up as open.

    On the server itself you should be able to verify that the ports are open and attached to processes by running Netstat.

    If Netstat on the server says the ports are open (and listening to your server's IP address interface, not JUST 127.0.0.1) then the next step is to diagnose either a lingering firewall issue or that the processes themselves are blocking outside access. Mail servers by default tend to block outside connections until they're configured to accept mail for the proper interface/domain, since otherwise they're spam-relay targets.

    After that you should verify that your client and server actually see each other (ping, traceroute) on the network and verify this isn't a connection issue.

    After that...I might look at a network dump using something like Wireshark to see if there's an issue with the handshake. Are the machines actually seeing each other, or is there a routing issue?

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  3. Error when I telnet localhost 143 : Could not open connection to the host on port 143

    My server is exchange server 2003.

    How this was resolved: Open Exchange System Manager Administrative Groups First administrative group Servers Mailserver Protocols IMAP4 Start the Default IMAP4 virtual server if not started. Restart if already started.

    In my case, I saw the Default IMAP4 virtual server in down position.

    Hope this help someone.

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