An adventure in connectivity - Chapter 1: Chasing the North American Wild Goose
It gets really frustrating trying to track down problems that don't really exist...
What seems like months ago, I installed RedHat on a box to use as a dial-on-demand/firewall type thingy for my home network. No GUI. No unnecesary stuff. Pretty much as basic as it can be. I checked the Modem HOWTO and all was well with my modem save for setting up a decent symlink to it in /dev. Then, I worked my way through the PPP HOWTO and all was going swimmingly. Until, that is, I got to the part where you start testing. I dialed out with Minicom, started pppd and life was good. (Well - it was good once I solved a minor routing issue.)
So I look at ifconfig and get the necessary IP addresses to check my connectivity. I ping localhost just fine and dandy like. No surprise there. So I ping the other side of my network card - also fine and unsurprising.
Next up? Ping a well known and highly available site by name to check DNS functionality. This time, not so much happy. So I ping the DNS servers themselves. No replies. OK - maybe a traceroute to see where it's breaking down. Nothing replies beyond the card's address. Now I'm becoming befuddled and beginning to think it's a subnet issue. Searching and asking friends nets a couple of things to try but they all look as they should. I checked subnet masks, default routes, .conf files, and way too many rc.foo init type files to absolutely no avail.
Anyway, after about 2 weeks of sporadically chasing my tail on this, I decided to try to ping the same sites and DNS servers from my Windows box which I (for now, anyway) use for my primary connectivity and on which I have no problems accessing any external resources. This time I got a surprise. No replies from any of them. Tracert gave me the same results.
I opened up an SSH client an pointed it toward a friend's box on which I have an account. It connected just fine.
Back to the dial-out box now to play with this new information.
Dial out? Check!
Damn the pings - full speed ahead!
Start up an ssh session to the external box and... BINGO!
So next I kicked off lynx and was able to surf with no problems.
So it seems that the giant conglomerate ISP that I am stuck with for the moment (because they bought the lovely little regional ISP from whom I got such good service and I haven't gotten all this stuff working yet in order to switch) must not be forwarding ICMP packets. And, of course, a search on there support web site (which I refuse to link to because it would only increase their Google page rank) says nothing about this. I don't dare call them either because they just kind of hem and haw when you mention anything other than Windows XP. Heaven forbid you even go outside the Redmond realm. Second tier support can't even handle that. (Oy.)
So I wasted WAY too much time troubleshoot a system that didn't really have any trouble to begin with. Like I said - frustrating.
Next step - automate the dial-out with a script and set up demand dialing.