[ubuntu-us-ma] Help connecting to two networks (Adding a virtual interface)

Greg Rundlett (freephile) greg at freephile.com
Tue Sep 1 15:41:42 BST 2009


I need a little help with networking.  I'm running Ubuntu Jaunty Jackalope 09.04

I have a LAN that has 2 separate logical networks. I want to be able
to have my PC be on both networks so that I can SSH to an Asterisk
server on the second LAN.  The PC LAN is 192.168.5.1-255 and the VoIP
LAN is 192.168.2.1-255.

Both lans use the same physical network. Vlan tagging separates the traffic.

How do I configure my notebook to be on both networks? I'm currently
using wireless (not using my wired interface at all) making it easier
to got to get up and go into a conference room.  I assume I need to
add a virtual interface on my wireless card so that I can be on both.
What is the preferred method to add a virtual interface?

I use Network Manager Applet which doesn't seem to touch
/etc/network/interfaces, yet I've seen posts that describe putting
something like the following in /etc/network/interfaces

auto wlan0
iface wlan0 inet dhcp
    netmask 255.255.255.0
    network 192.168.5.0
    broadcast 192.168.5.255
    gateway 192.168.5.1

auto wlan0:1
iface wlan0:1 inet dhcp
    netmask 255.255.255.0
    network 192.168.2.0
    broadcast 192.168.2.255
    gateway 192.168.2.1

and then you would restart networking with

sudo /etc/init.d/networking restart


except it's obviously wrong because I'm getting these errors

 * Reconfiguring network interfaces...postconf: fatal: open
/etc/postfix/main.cf: No such file or directory
Internet Systems Consortium DHCP Client V3.1.1
Copyright 2004-2008 Internet Systems Consortium.
All rights reserved.
For info, please visit http://www.isc.org/sw/dhcp/

wmaster0: unknown hardware address type 801
wmaster0: unknown hardware address type 801
Listening on LPF/wlan0/00:21:6a:51:df:a4
Sending on   LPF/wlan0/00:21:6a:51:df:a4
Sending on   Socket/fallback
Internet Systems Consortium DHCP Client V3.1.1
Copyright 2004-2008 Internet Systems Consortium.
All rights reserved.
For info, please visit http://www.isc.org/sw/dhcp/

wmaster0: unknown hardware address type 801
wmaster0: unknown hardware address type 801
Listening on LPF/wlan0/00:21:6a:51:df:a4
Sending on   LPF/wlan0/00:21:6a:51:df:a4
Sending on   Socket/fallback
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 4
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 8
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 10
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 12
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 8
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 14
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 5
No DHCPOFFERS received.
No working leases in persistent database - sleeping.
 * Reloading /etc/samba/smb.conf smbd only
   ...done.
 * if-up.d/mountnfs[wlan0]: waiting for interface wlan0:1 before doing
NFS mounts
postconf: fatal: open /etc/postfix/main.cf: No such file or directory
Internet Systems Consortium DHCP Client V3.1.1
Copyright 2004-2008 Internet Systems Consortium.
All rights reserved.
For info, please visit http://www.isc.org/sw/dhcp/

wmaster0: unknown hardware address type 801
SIOCSIFFLAGS: Cannot assign requested address
SIOCSIFFLAGS: Cannot assign requested address
wmaster0: unknown hardware address type 801
Bind socket to interface: No such device
Failed to bring up wlan0:1.

I also see that 'network-admin' (System -> Administration -> Network)
is an application that will allow me to configure various network
settings, however it doesn't seem to offer a way to accomplish what
I'm trying to do.


Greg Rundlett

nbpt 978-225-8302
m. 978-764-4424
-skype/aim/irc/twitter freephile
http://profiles.aim.com/freephile



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