Telnet Confusion

[osuman]

I have 2 routers in different physical locations, each router has 2 WAN interfaces from separate ISPs. All the WAN interfaces are up and carry traffic.

My problem arises when I try to telnet to either router from a different location (i.e. home). For the sake of discussion, let's say the IP address for the WAN interfaces are as follows:

Router 1 - WAN 1 - 1.1.1.1
Router 1 - WAN 2 - 2.2.2.2
Router 2 - WAN 1 - 3.3.3.3
Router 2 - WAN 2 - 4.4.4.4

For some reason, when I'm at home and try to telnet to 1.1.1.1, I can't make the connection, nor can I ping the address. However, when I am at work, I can successfully telnet to 1.1.1.1. Also, when I'm at home I can telnet to 2.2.2.2.

To make things even more confusing, I have a similar problem with router 2. From home I can't telnet 3.3.3.3 but can to 4.4.4.4. However, if I first telnet to router 1 using the 2.2.2.2 network and then, from the router, open a connection to 3.3.3.3, it works!

I don't believe this is a problem with the WAN interfaces. It seems like my ability to telnet to some of the interfaces depends on where I'm coming from. However, everything is setup the same as far as permissions, routing, etc.

Any ideas?

 

[jneiberger]

The most likely problem is that the Internet provider you use at work does not advertise their serial link IP addresses to the rest of the world. If you try to ping or Telnet from within the ISPs address space then you succeed. If you try to do either from a connection that uses a different ISP, it will fail because your ISP doesn't know how to get to those addresses.