Re: wireless can DHCP but not DNS?
On Thu, 22 May 2014 15:08:36 -0400
Tom Roche <Tom_Roche@pobox.com> wrote:
>
> summary: box ethernets via wire, but all wireless fails, including
> known-good providers: `ifconfig -a` shows a wireless IP#, but
> `nslookup` fails. How to fix or debug?
>
> details:
>
> I'm running LMDE UP8
>
> https://en.wikipedia.org/wiki/Linux_Mint#Linux_Mint_Debian_Edition
> http://blog.linuxmint.com/?p=2544
>
> up-to-date on a new ThinkPad (new to me, anyway :-) with
>
> $ inxi -Fxz
> > System: Host: <filter> Kernel: 3.11-2-amd64 x86_64 (64 bit, gcc:
> > 4.8.1) Desktop: Cinnamon 2.0.14 Distro: LinuxMint 1 debian
> > ...
> > Network: Card-1: Intel Centrino Advanced-N 6200 driver: iwlwifi
> > ver: in-tree: bus-ID: 03:00.0 IF: wlan0 state: down mac: <filter>
> > Card-2: Intel 82577LM Gigabit Network Connection driver:
> > e1000e ver: 2.3.2-k port: 1820 bus-ID: 00:19.0 IF: eth0 state: up
> > speed: 100 Mbps duplex: full mac: <filter>
>
> I run wired ethernet at home and work, and installed debian on the
> newer laptop via wire without problems. I also have an older laptop
> with an older LMDE (UP5) which I won't be updating until I get
> everything working on the newer box :-( Wireless works as expected on
> the older laptop, including at the following locations:
>
> * home (FreedomPop Hub Burst modem/router, security=WPA personal with
> encryption=AES)
> * nearby municipal wireless (unsecured)
> * work (security=WPA enterprise)
>
> But at each of those locations, wireless fails on the newer laptop in
> the same way: I can DHCP (at least, I get an IP address) but not
> DNS ... which makes no sense to me! For example:
>
> At home I can enable wireless on the modem/router, then startup the
> older box. It autoconnects to that SSID, and then
>
> me@OldBox:~$ date ; nslookup www.google.com ; date
> > Thu May 22 13:08:43 EDT 2014
> > Server: 192.168.15.1
> > Address: 192.168.15.1#53
> ...
>
> me@OldBox:~$ date ; sudo ifconfig -a
> > Thu May 22 13:08:45 EDT 2014
> ...
> > wlan0 Link encap:Ethernet HWaddr <filter>
> > inet addr:192.168.15.56 Bcast:192.168.15.255
> > Mask:255.255.255.0 inet6 addr: <filter> Scope:Link
> > UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> > RX packets:40217 errors:0 dropped:0 overruns:0 frame:0
> > TX packets:32431 errors:0 dropped:0 overruns:0 carrier:0
> > collisions:0 txqueuelen:1000
> > RX bytes:15583645 (14.8 MiB) TX bytes:9273602 (8.8 MiB)
>
> I can then browse to pages normally (using firefox). I then disable
> the old box's wireless (via NetworkManager), enable the new box's
> wireless, and connect ... or at least, NetworkManager gives
> connection notification. But when I do
>
> me@NewBox ~ $ date ; nslookup www.google.com ; date
> > Thu May 22 13:11:22 EDT 2014
> > ;; connection timed out; no servers could be reached
> > Thu May 22 13:11:37 EDT 2014
>
> me@NewBox ~ $ date ; sudo ifconfig -a
> > Thu May 22 12:53:07 EDT 2014
> ...
> > wlan0 Link encap:Ethernet HWaddr <filter>
> > inet addr:192.168.15.71 Bcast:192.168.15.255
> > Mask:255.255.255.0 inet6 addr: <filter> Scope:Link
> > UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> > RX packets:998 errors:0 dropped:0 overruns:0 frame:0
> > TX packets:1099 errors:0 dropped:0 overruns:0 carrier:0
> > collisions:0 txqueuelen:1000
> > RX bytes:77446 (75.6 KiB) TX bytes:177995 (173.8 KiB)
>
> FWIW, I have the same wireless experience at the other locations
> (open municipal wifi and secured wifi @ work): older box "just
> works," newer box connects and gets IP# but can't DNS (or browse).
>
> Given that the older box (and in the latter cases, lots of other
> devices) works with these SSIDs, I suspect they are not
> misconfigured. Given that NetworkManager seems happy, and DHCP at
> least partly works, on the newer box, I suspect the newer box does
> not have a hardware problem. So I tend to suspect a software problem
> on the newer box. Am I missing something?
>
> Mostly I'd like to know,
>
> 1. How to fix or debug the newer laptop?
>
> 2. How can the newer box get an IP# but no DNS server#s? I've used
> DHCP for many years but don't recall seeing this behavior before,
> except with misconfigured routers--which does not seem to apply in
> this case, because, in every instance, the old box works as expected.
>
> Your assistance is appreciated, Tom Roche <Tom_Roche@pobox.com>
>
>
- Can you access the internet at all or is it only the DNS ? Try
retrieving the Debian homepage
$ wget http://130.89.148.14
- Compare /etc/resolv.conf and /etc/nsswitch.conf between the two
systems.
- Compare
$ ip route
between the two systems.
- ifconfig is deprecated, and i've seen case where it gives wrong
information. use ip addr
$ ip addr
- Are you, by any chance, blocking things with iptables ?
$ iptables -n -L
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