Help: No internet connection

[Rick Sewill]

On Mon, 2009-12-14 at 11:58 -0500, R. G. Newbury wrote: 
> >>> On Sun, 2009-12-13 at 13:35 -0700, simon.schneebeli at okko.org wrote:
> 
> >>>> At my brothers place I managed to connect to the internet with no
> >>>> problem. All programmes worked, so I could add all the additional
> >>>> programs I needed and install the latest updates.
> 
> >> RPM: "Couldn't resolve host"
> >>
> >> To mention again: These messages appear immediately, not only after some
> >> seconds like the server doesn't answer...
> > 
> > What strikes me about that list is the ones that don't work are
> > NetworkManager aware - I wonder if NetworkManager is telling them the
> > connection is offline.
> 
> Check that your router has IP address entries for your ISP's DNS server(s).
> 
> Check that you have not forgotten that you turned on access restrictions 
> on your router, and in particular that you have not limited the number 
> of DHCP addresses which the router can serve out, and that you are not 
> over that limit. (Been *there*...real hair-puller!). This is a likely 
> possibility given that you got things to work at your brother's house.. 
> Maybe he has NO security settings enabled??? Check that DHCP is turned ON.
> 
> Check that system-config-network has IP address entries for your ISP's 
> DNS server(s) and that the gateway address in on the correct network (ie 
> 192.168.1.1 and not by mistake 192.168.0.1 etc.) You might want to try 
> settings a STATIC IP address to avoid DHCP contention errors. This will 
> not help if you have MAC address filtering turned ON, at the router.
> 
> At a console enter:
> 'service NetWorkManager stop'
> 'service wpa_supplicant stop'
> 'service ip6tables stop'
> 
> With a WIRED connection ONLY:
> 'service iptables restart'
> 'service network restart'
> 
> This should A) stop all the wireless services and things we don't want 
> in the way, and B) start ONLY the things we want to see.
> 
> Then:
> 'ifconfig eth0'  should show, in the second line something like:
> "inet addr:192.168.1.99  Bcast:192.168.1.255  Mask:255.255.255.0"
> If not, try 'ifup eth0' then 'ifconfig eth0' again.
> 
> If you have an address, start with 'ping 192.168.1.1' (or whatever your 
> router's IP address is). That *should* work. Then try 'ping yahoo.com'. 
> If that works, then the problem(s) are internal to the configuration of 
> the programs you are running (ie proxy settings in Firefox)
> 
> If you used a static IP, but cannot ping the router, then it is likely 
> the wiring or router setup. If you get no address reported, then the 
> network setup is wrong. (This is why a static address is useful for this 
> case).
> 
> If you get an IP address and can ping the router, but cannot ping 
> externally, then it is probably the router's DNS setup. When the wired 
> connection works, THEN you can try to set up wireless (and/or revert to 
> a DHCP IP scheme).
> 
> And if you ARE going to set up wireless then I strongly recommend wicd 
> (at wicd.sourceforge.net) as a replacement for NetworkManager. It works 
> at least as well as NM, but has a MUCH more transparent setup and 
> control structure and can remember/act upon different wireless and wired 
> connections, such as you need for a laptop at work and at home. For this 
> it helps if you use 'static DHCP' where the router parses the MAC 
> address and delivers an address accordingly, triggered by the DHCP 
> request from the laptop etc.
> 
> Geoff

Also, please do "netstat -rn" to see your routing table on your PC.
You indicated you could ping an Internet address,
when you type ping www.xxx.yyy.zzz, which led me to believe 
you have a default route pointing to your router, but I would check.
You may have other routes in your routing table, which explicitly 
route certain IP address ranges to the wrong gateway IP address.
"netstat -rn" should give us the needed routing table information.

-Rick