Need Help with Debian Networking

[Michael Butash]

I've noticed weird issues depending on the version of network-manager 
managing the connections.  Since you're using the interfaces file, it's 
specifically not managing it, which usually comes with the benefit of 
conflicting default gateway routes and other fun errata.

It looks like you have two different dhcp pools, one that is feeding the 
local gateway as a dns resolver, and another that is passing down the 
external cox dhcp dns servers there too.  Does your router do some kind 
of "dmz" config or anything for wireless, like a guest lan config?  They 
sometimes do wonky bridging scenarios between vlans locally to segment 
traffic for some guise of security, could be causing this as well.

Pay attention to which interface is bound to which routes.  The default 
route on a given interface will be used for internet traffic regardless, 
and I've seen ubuntu/nm install dual defaults on dhcp that break the 
hell out of everything between wifi and wireless - make sure you only 
have one default route.

-mb


On 06/20/2014 08:01 PM, Ed wrote:
> I think the problem may be at the router - can you show the ifconfig
> (if?) when you are connected via wifi - I would look at the network
> segment, is it the same as the wired connection? my guess is not.
>
> 192.168 networks are not routed and I think you have two - wired and
> wifi. While a bridge on the AP would be quick & easy (and a bad idea)
> - a VPN would be more secure and more useful overall. you could even
> use it when on the road to access your wired network.
>
> I'm not a Debian user so ymmv - There are many on the list so getting
> cli from them would be better - Ed
>
> On Thu, Jun 19, 2014 at 11:46 AM, Mark Phillips
> <mark at phillipsmarketing.biz> wrote:
>> I am running Debian testing. When I reboot and plug in my network cable, I
>> am able to ping external servers and machines on my LAN. Basically, it all
>> just works with the network cable plugged in.
>>
>> When I reboot and turn on the wifi (ie there is a switch on my laptop to
>> turn on/of wifi) and have the network cable disconnected, I can ping
>> external sites but not internal machines. I get the message Destination Host
>> Unreachable. If  I then plug in the network cable (and turn off wfi) I am
>> able to ping both internal and external servers. If I now disconnect the
>> cable and turn on wifi again, I can ping both external and internal servers.
>>
>> /etc/network/interfaces
>> auto eth0
>> iface eth0 inet static
>>          address 192.168.25.150
>>          netmask 255.255.255.0
>> gateway 192.168.25.1
>> dns-search ph.cox.net
>> dns-nameservers 68.105.28.12 68.105.29.12 68.105.28.11
>>          gateway 192.168.25.1
>>
>> allow-hotplug wlan0
>> iface wlan0 inet dhcp
>>
>> I looked at resolv.conf and route for the two scenarios -
>>
>> 1. Reboot into cable connected network -
>> root at orca:/home/mark# route
>> Kernel IP routing table
>> Destination     Gateway         Genmask         Flags Metric Ref    Use
>> Iface
>> default         gateway         0.0.0.0         UG    0      0        0 eth0
>> link-local      *               255.255.0.0     U     1000   0        0 eth0
>> 192.168.25.0    *               255.255.255.0   U     0      0        0 eth0
>>
>> root at orca:/home/mark# cat /etc/resolv.conf
>> # Generated by NetworkManager
>> search ph.cox.net
>> nameserver 68.105.28.12
>> nameserver 68.105.29.12
>> nameserver 68.105.28.11
>>
>> 2. Reboot into wifi
>> root at orca:/home/mark# route
>> Kernel IP routing table
>> Destination     Gateway         Genmask         Flags Metric Ref    Use
>> Iface
>> default         gateway         0.0.0.0         UG    0      0        0
>> wlan0
>> link-local      *               255.255.0.0     U     1000   0        0
>> wlan0
>> 192.168.25.0    *               255.255.255.0   U     0      0        0 eth0
>> 192.168.25.0    *               255.255.255.0   U     0      0        0
>> wlan0
>>
>> root at orca:/home/mark# cat /etc/resolv.conf
>> nameserver 192.168.25.1
>>
>> I could change interfaces to have a static IP for wifi, and it would work
>> when I reboot. However, for that occasional visit to Starbucks my wifi would
>> not work.
>>
>> What do I need to do to make my wifi work both at home and on the road?
>>
>> Thanks,
>>
>> Mark
>>
>> ---------------------------------------------------
>> PLUG-discuss mailing list - PLUG-discuss at lists.phxlinux.org
>> To subscribe, unsubscribe, or to change your mail settings:
>> http://lists.phxlinux.org/mailman/listinfo/plug-discuss
> ---------------------------------------------------
> PLUG-discuss mailing list - PLUG-discuss at lists.phxlinux.org
> To subscribe, unsubscribe, or to change your mail settings:
> http://lists.phxlinux.org/mailman/listinfo/plug-discuss