Go Back   TechArena Community > Technology > Networking & Security
Become a Member!
Forgot your username/password?
Register Tags Active Topics RSS Search Mark Forums Read

Sponsored Links



Telnet disconnects while testing Port 25 SMTP

Networking & Security


Reply
 
Thread Tools Search this Thread
  #1  
Old 05-04-2010
Member
 
Join Date: Nov 2009
Posts: 43
Telnet disconnects while testing Port 25 SMTP
  

I have Windows Server 2008 R2 operating system on the server. The server is not running any Active Directory and is not a part of any Domain. The problem which I am facing is, I cannot run any hMailserver program on the computer. The remote mail client does not connect and hence I tried to use Telnet. While using Telnet is shows that the server is connected to port 25 SMTP successfully but when the telnet is used on client machine, it get disconnected immediately. The hMailerserver log shows that the telnet request was received and responded to, but the connection was disconnected. Therefore If anybody knows why Telnet disconnects while testing Port 25 SMTP then please share some information about the topic. For additional information, all the client machines are running on Windows 7 operating system. Thanks in advance.

Reply With Quote
  #2  
Old 05-04-2010
Member
 
Join Date: May 2009
Posts: 1,072
Re: Telnet disconnects while testing Port 25 SMTP

Are there any firewalls running on the computer? If yes then it could be the reason behind the Telnet session getting disconnected. All the firewalls have a tendency to block all the unknown traffic originating or terminating on the computer. Due to this tendency sometimes the traffic desired by the user is also blocked which gives rise to the problem similar to the one you are facing. Try adding the process of the hMailserver program to the known applications list of the firewall and then see if you are able to connect using Telnet.
Reply With Quote
  #3  
Old 05-04-2010
Member
 
Join Date: Jul 2009
Posts: 1,107
Re: Telnet disconnects while testing Port 25 SMTP

I think there is some problem with the network configured due to which you are facing such problems. There is an application known as Wireshark which gives logs of all the events on the network. Install the Wireshark on the server and then see all the errors when the telnet connection is tried to establish. It will give exact errors while the data packets are being transferred between Client and the server machine which will help you in diagnosing the problem with your network.
Reply With Quote
  #4  
Old 05-04-2010
Member
 
Join Date: Nov 2009
Posts: 43
Re: Telnet disconnects while testing Port 25 SMTP

Thanks for replying to the post really fast. As suggested I tried to move the process of the mail server to the white list of the firewall but still the telnet session disconnected frequently. Also I installed Wireshark on the server ti monitor all the logs of the data packets and found out that while using telnet, the system gives error saying "Telnet session disconnected due to improper header". How to solve this problem? Please help.
Reply With Quote
  #5  
Old 05-04-2010
Member
 
Join Date: Nov 2009
Posts: 846
Re: Telnet disconnects while testing Port 25 SMTP

The default IP version of Windows 7 is IPv6 while the default IP version of Windows 2008 server is Ipv4. Therefore when the computer running on Windows 7 is connected on the network, it causes protocol mismatch. Hence you will have to disable the IPv6 support of Windows 7 inorder to make the network work properly. To disable the Ipv6 support, go to network connection and then open the TCP/IP properties. Now remove the check mark from the "Enable IPv6 support" and save the settings. Reboot and see if the telnet is successful or not.
Reply With Quote
  #6  
Old 05-04-2010
Member
 
Join Date: Jun 2009
Posts: 886
Re: Telnet disconnects while testing Port 25 SMTP

You will have to set the priority of the server higher than the mail server to make the telnet connection work. To make the priority of the server higher, Set the priority of the local IP address of the server higher than the hmailservers autoban level. Once done, restart the firewall with Automatic Protection. If the firewall does not restart then reboot the whole system. After rebooting the telnet connection will work.
Reply With Quote
Reply

  TechArena Community > Technology > Networking & Security
Tags: , , , , , , , ,



Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads for: "Telnet disconnects while testing Port 25 SMTP"
Thread Thread Starter Forum Replies Last Post
What port does telnet use? SadyQ Networking & Security 4 02-01-2012 09:29 PM
No response to telnet on port 25 Hamlet Networking & Security 5 01-04-2010 10:59 AM
How can i telnet to port Drogbaa Networking & Security 4 16-07-2009 10:21 PM
SBS2003 SMTP Port Outgoing Port ERro CaspaR Small Business Server 1 20-06-2009 10:05 AM
testing connection with telnet RaeS Windows Vista Mail 3 28-04-2008 11:15 PM


All times are GMT +5.5. The time now is 02:59 PM.