Simpler Navigation for Servers and Operating Systems - Please Update Your Bookmarks
Completed: a much simpler Servers and Operating Systems section of the Community. We combined many of the older boards, so you won't have to click through so many levels to get at the information you need. Check the consolidated boards here as many sub-forums are now single boards.
If you have bookmarked forums or discussion boards in Servers and Operating Systems, we suggest you check and update them as needed.
Networking
cancel
Showing results for 
Search instead for 
Did you mean: 

Dial-up versus LAN connection

Stefano_80
Occasional Advisor

Dial-up versus LAN connection

Hi all,

my problem is the following.
I have a system made up by these components:

PC A--> Router A (NAT) ---> Router B ---> PC B

PC A and Router A belong to the same LAN1.
Router B belongs to LAN2 and accepts only a given range of addresses not belonging to LAN1. Router B nats correctly source addresses coming from LAN1 into the given range of admitted addresses.
When inserted into LAN1, PC A can ping PC B, its address being correctly natted by router B.

Yet when using a dial-up connection landing on a Linux machine acting as a RAS, PC A gets an address from LAN1 ... BUT it cannoct reach destination PC B.

Is this a mystery? I suspect it depends on the configuration of the Linux machine (RAS).

Could you help me with some hints?

Thanks in advance,

Stefano.
2 REPLIES
Ron Kinner
Honored Contributor

Re: Dial-up versus LAN connection

Can PC A ping Router A when dialed up?

What does

netstat -rn

look like on PC A?

Are you positive that router B's NAT source list includes PC A's RAS address? (And that PC B knows how to get to them?)

Could someone have squatted on the IP addresses assigned by RAS? Had that happen where I work. Of 12 addresses in the RAS pool, 6 were occupied by squatters (people would ping an address and if no response assume it was vacant). Try pinging all addresses from a device on A when the RAS does not have any calls.

Does the linux box do any filtering? IPCHAINS or the like?

Ron
Stefano_80
Occasional Advisor

Re: Dial-up versus LAN connection

Thanks Ron for the reply!

I found the solution myself and it was simply depending on the fact that no routes to PC B had been set on the RAS Linux machine... Once I provided the RAS with this information, everything turned up right! (PC A could ping router A when connected via dial-up and the range of available addresses was very large [an entire subnet!])

Thank you anyway for the list of possible causes! Always useful!

Stefano.