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Connecting to Home Network


I am unable to connect some of the services that I host from my laptop at home, such as SMTP and MySQL on port numbers 25 and 3306 respectively.
But I am able to some services such as Telnet, Remote Desk Connection, SSH.
Here are my details
ISP: Time Warner
Connection Type: Cable
Router: Lynksys
Port Farwarding: enabled port farwarding to HTTP, Telnet, HTTPS, Remote Desktop Connection, SSH, MySQL etc to my laptop.
Connection Type on Laptop: wireless card
OS: Windows XP/ I also checked with SuSE linux
Firewall: I opened all ports for all the above mentioned ports
Netstat query results:

I would really appreciate if somebody helps me why I am unable to connect to my mysql and smtp servers, mind you, I am trying to connect from a private network, I don't know if that makes any difference.

Jun 5 '07 #1
1 2209
Hi ynyus75,

Try the following tests:
1.) from the laptop, try to telnet to (assuming that's your laptop's IP address)
2.) from another machine on the same subnet, try to telnet to
3.) from any machine on the same subnet, try to telnet to (assuming that is your router's public IP address).

If all three tests fail then the SMTP service may not be running, may not be bound to the right IP (check properties of the SMTP virtual server in the IIS mgmt console) or you may have a software firewall on the laptop that is interfering.

If 1 works but 2 & 3 fail then the problem is most likely a software firewall on the laptop.

If only 3 fails then the problem might be with the router's port forwarding (but on some routers this test will always fail)

If all three tests pass, then the ISP is almost certainly blocking the ports. This is a common practice used to help prevent spam/viruses. To test this, you can try changing the port that your SMTP server listens on to something you know is not blocked (i.e. try using port 23 but don't forget to stop your telnet service first).

Also, you can try running a network capture program like wireshark (http://www.wireshark.org) and then doing a port scan of your system from somewhere like www.grc.com. If wireshark doesn't see the traffic on port 25, and grc.com reports the port as closed or stealth then you can be pretty sure your ISP is blocking it, or the router's port forwarding is broken.

If you think the router's port forwarding is broken, make sure your software firewall is working then try removing all of the port forwarding rules and setting the router's DMZ address to (this is basically the same as port forwarding all ports).

If you think there might be a software firewall interfering, make sure that you have disabled the DMZ feature and re-enabled the port forwarding rules, then try disabling the firewall on your laptop completely (and make sure you don't accidentally have multiple firewalls installed - norton? mcafee? windows firewall? etc.) .

That's all I can think of right now.

Good luck!

Jan 12 '08 #2

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