Why won't routers route back inside LAN?

pquiring · 09-03-2008, 07:22 PM

I have a DNS name at my office that is updated with dyndns.org
Let's say the domain name is domain.com.
Let's say I have an email server running on a server at the office on a static IP, say 192.168.1.3.
The router is setup to redirect ports 25 and 110 to the email server.
From the Internet I can connect no problem:
telnet domain.com 25
or
telnet domain.com 110
Works fine.
But if I try these commands from "inside" the office it doesn't work.

Why???

Thanks.

**johnwill** · 09-05-2008, 09:37 AM

Your router doesn't have NAT loopback, which is why it doesn't work.

pquiring · 09-06-2008, 11:57 AM

Thanks.

I noticed this issue on many different routers. Such as cheap home-routers (linksys). We are using a cisco router at work so I'll see if our ISP can set this up for us.

Thanks again.

**johnwill** · 09-06-2008, 03:21 PM

I can't believe that the Cisco won't do this, so you probably should be able to get it working.

09-03-2008, 07:22 PM	#1 (permalink)
pquiring Registered User Join Date: Sep 2008 Posts: 4 OS: Window XP Vista Server 2003	Why won't routers route back inside LAN? I have a DNS name at my office that is updated with dyndns.org Let's say the domain name is domain.com. Let's say I have an email server running on a server at the office on a static IP, say 192.168.1.3. The router is setup to redirect ports 25 and 110 to the email server. From the Internet I can connect no problem: telnet domain.com 25 or telnet domain.com 110 Works fine. But if I try these commands from "inside" the office it doesn't work. Why??? Thanks.

09-05-2008, 09:37 AM	#2 (permalink)
johnwill Manager, Networking Forums Join Date: Sep 2002 Location: S.E. Pennsylvania, US Posts: 41,899 OS: Windows 7, XP-Pro, Vista, Linux Blog Entries: 1	Re: Why won't routers route back inside LAN? Your router doesn't have NAT loopback, which is why it doesn't work. __________________ If TSF has helped you, Tell us about it! or Donate to help keep the site up! Microsoft MVP - Windows Desktop Experience

09-06-2008, 11:57 AM	#3 (permalink)
pquiring Registered User Join Date: Sep 2008 Posts: 4 OS: Window XP Vista Server 2003	Re: Why won't routers route back inside LAN? Thanks. I noticed this issue on many different routers. Such as cheap home-routers (linksys). We are using a cisco router at work so I'll see if our ISP can set this up for us. Thanks again.

09-06-2008, 03:21 PM	#4 (permalink)
johnwill Manager, Networking Forums Join Date: Sep 2002 Location: S.E. Pennsylvania, US Posts: 41,899 OS: Windows 7, XP-Pro, Vista, Linux Blog Entries: 1	Re: Why won't routers route back inside LAN? I can't believe that the Cisco won't do this, so you probably should be able to get it working. __________________ If TSF has helped you, Tell us about it! or Donate to help keep the site up! Microsoft MVP - Windows Desktop Experience