Help: No internet connection

R. G. Newbury newbury at mandamus.org
Mon Dec 14 16:58:36 UTC 2009


>>> 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












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