Internet connection on Linux

Thanks for the replies - I'll have a play the next time I get a chance
(probably towards the end of the week)..

Chris

On 2008-04-26, CCW <c.c.wood@gmail.com> wrote:
> Hi,
>
> I've got a FC7 server, running a workgroup with ~10 windows PCs. I'm
> sharing the internet connection via FC7, so my setup is:
>
>
> Router (192.168.0.1) ------ (eth0) 192.168.0.2 - (eth1) 192.168.1.1
> ------ Windows computers (1.2 - 1.10)
>
> All of the windows computers can use the internet fine, but my FC7
> server can't! I can access websites / ping by ip address but not by
> name. I've checked the dns settings, and they seem to be ok, and I'm
> a bit lost as to what else to check! Any ideas what could be wrong?
>

I encountered a similar problem and was able to fix it a couple days
ago. The cause of the problem may be completely different from yours,
but in case it's the same or similar, here's a brief summary - put in
vague, nontechnical terms because I'm not a DSL or networking expert and
I didn't investigate in detail what was happening:

The DSL modem I was using appeared to have an inside line of
communictation to the windows machines (probably with respect to DHCP
and/or NAT). My firewall was getting an address via DHCP from the modem
of 192.168.0.6 instead of something sensible (and expected), such as my
current valid address: 75.166.182.133. The windows machines (on the
same internal network as my Linux machine, protected by the firewall)
were able to deal with this wierdness, but my Linux system, at least
with respect to browsing, was not. (The firewall is configured to
perform NAT via iptables - perhaps the modem was also doing NAT.)

The fix was to change back to a modem I was using before - it gave my
firewall reasonable IP addresses (i.e., passed on the address obtained
from the qwest server) and the problem went away. (I had switched to
the other [problem] modem during a call to qwest tech. support to check
whether a problem with slow speeds [unrelated to the above problem] was
caused by the modem - it wasn't, but I had left the 2nd modem connected,
thinking it should work the same.)

It could be that this "windows-friendly" modem is configurable such that
it does not do this wierdness re. DCHP (and perhaps NAT). (Maybe it's
as simple as turning NAT off.)

(Anyone reading this who knows the complete explanation of what happened
here and is thinking something like "obviously, what was happening was
...." is welcome to put the ... into words; besides myself, I'm sure
others would be enlightened by and appreciate it; and corrections to my
probably naive explanation are welcome.)


--

Jim Cochrane <allergic-to-spam@no-spam-allowed.org> writes:

>On 2008-04-26, CCW <c.c.wood@gmail.com> wrote:
>> Hi,
>>
>> I've got a FC7 server, running a workgroup with ~10 windows PCs. I'm
>> sharing the internet connection via FC7, so my setup is:
>>
>>
>> Router (192.168.0.1) ------ (eth0) 192.168.0.2 - (eth1) 192.168.1.1
>> ------ Windows computers (1.2 - 1.10)
>>
>> All of the windows computers can use the internet fine, but my FC7
>> server can't! I can access websites / ping by ip address but not by
>> name. I've checked the dns settings, and they seem to be ok, and I'm
>> a bit lost as to what else to check! Any ideas what could be wrong?

OK, your FC7 can also see the internet fine. If they can do things by IP
address, your routes, etc are fine. The problem is with DNS.
What does /etc/resolv.conf say? Can you ping that machine address?

what is the resolv.conf on the windows machines?


>>

>I encountered a similar problem and was able to fix it a couple days
>ago. The cause of the problem may be completely different from yours,
>but in case it's the same or similar, here's a brief summary - put in
>vague, nontechnical terms because I'm not a DSL or networking expert and
>I didn't investigate in detail what was happening:

>The DSL modem I was using appeared to have an inside line of
>communictation to the windows machines (probably with respect to DHCP
>and/or NAT). My firewall was getting an address via DHCP from the modem
>of 192.168.0.6 instead of something sensible (and expected), such as my
>current valid address: 75.166.182.133. The windows machines (on the
>same internal network as my Linux machine, protected by the firewall)
>were able to deal with this wierdness, but my Linux system, at least
>with respect to browsing, was not. (The firewall is configured to
>perform NAT via iptables - perhaps the modem was also doing NAT.)

>The fix was to change back to a modem I was using before - it gave my
>firewall reasonable IP addresses (i.e., passed on the address obtained
>from the qwest server) and the problem went away. (I had switched to
>the other [problem] modem during a call to qwest tech. support to check
>whether a problem with slow speeds [unrelated to the above problem] was
>caused by the modem - it wasn't, but I had left the 2nd modem connected,
>thinking it should work the same.)

>It could be that this "windows-friendly" modem is configurable such that
>it does not do this wierdness re. DCHP (and perhaps NAT). (Maybe it's
>as simple as turning NAT off.)

>(Anyone reading this who knows the complete explanation of what happened
>here and is thinking something like "obviously, what was happening was
>..." is welcome to put the ... into words; besides myself, I'm sure
>others would be enlightened by and appreciate it; and corrections to my
>probably naive explanation are welcome.)


>--

On 26 Apr, 17:48, Jack Snodgrass <jacks_temp_id_blu...@verizon.net>
wrote:
> On Sat, 26 Apr 2008 08:37:27 -0700, CCW wrote:
> > Thanks for the replies.
>
> > My /etc/resolv.conf is:
>
> > ; generated by /sbin/dhclient-script
> > nameserver 208.67.222.222
> > nameserver 208.67.220.220
>
> > They are the IP addresses of Open DNS (http://www.opendns.com/).
>
> > Running
> > %> hostwww.yahoo.com208.67.222.222
>
> > gives:
>
> > Using domain server:
> > Name: 208.67.222.222
> > Address: 208.67.222.222#53
> > Aliases:
>
> >www.yahoo.comis an alias forwww.yahoo-ht3.akadns.net
> >www.yahoo-ht3.akadns.nethas address 87.248.113.14
>
> > I get a similar response from 208.67.220.220
>
> > Does this provide any more info?
>
> > Thanks,
> > Chris
>
> ... that all looks right... you said in the original message:
>
> "I can access websites / ping by ip address but not by name."
> ... and it's not a /etc/resolv.conf issue.. then it's a strange one...
>
> What happens when you do:
> hostwww.yahoo.com
> and not specify a name server.... in theory... it should pick one from
> your /etc/resolv.conf file if it's reading it.
>
> maybe your config is really screwed up and your not looking at your
> /etc/resolv.conf file... do this:
> cat /etc/nsswitch.conf | grep hosts | grep -v "#"
> and see what you get. I get:
> cat /etc/nsswitch.conf | grep hosts | grep -v "#"
> hosts: files dns
> which says to look in the /etc/hosts file and then do a dns lookup
> if it's not found... what does your config show for that?

For this I get

$> cat /etc/nsswitch.conf | grep hosts | grep -v "#"
hosts: files wins


If this isn't what I should have, I do I change it back?!
Chris