Routing help

[ukchucktown]

Okay, hopefully somebody with some routing experience can help me out. I think my problem might be pretty simple to solve. I tinkered around with some different route commands but nothing has worked so far. I'm trying to create a virtual net of windows 2003 servers running in VirtualBox on a laptop. Where it gets tricky is I'm creating a tap interface that I bridge to from the virtual machines. I'm not having any problems with the tap interface or the bridging from VirtualBox. It works but I can't ping my router or outside addresses from the virtual machines unless I bridge to eth0 and keep the VMs on the same subnet as my router. When I bridge to the tap interface, tap0, I can ping eth0 on my laptop but that's as far as I get. It's safe to assume I need to modify my routing table or maybe enable packet forwarding. I posted my interface and route information from the ip command.

In a nutshell, eth0 on the laptop is 192.168.0.3, assigned its address from a router at 192.168.0.1. I set the tap interface to use 192.168.100.1. My VM bridges to the tap interface and uses a static IP of 192.168.100.2. It uses the tap interface as its gateway. I'm able to ping all the internal addresses from the host or the VM. My only problem is reaching the router and outside addresses from the windows VM. I wouldn't bother with this configuration if one of my virtual machines was not a domain controller. It needs a static IP address and the eth0 address on my laptop changes so I can't bridge to eth0 and use DHCP.

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN 
  link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00      
  inet 127.0.0.1/8 scope host lo                 
  inet6 ::1/128 scope host                    
    valid_lft forever preferred_lft forever           
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 100
  link/ether 00:1c:25:10:e7:33 brd ff:ff:ff:ff:ff:ff                
  inet 192.168.0.3/24 brd 192.168.0.255 scope global eth0              
  inet6 fe80::21c:25ff:fe10:e733/64 scope link                   
    valid_lft forever preferred_lft forever                    
3: wmaster0: <UP,LOWER_UP> mtu 0 qdisc pfifo_fast state UNKNOWN qlen 1000       
  link/ieee802.11 00:1b:77:90:e6:43 brd 00:00:00:00:00:00              
4: wlan0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
  link/ether 00:1b:77:90:e6:43 brd ff:ff:ff:ff:ff:ff                   
5: vboxnet0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000         
  link/ether 0a:00:27:00:00:00 brd ff:ff:ff:ff:ff:ff                   
6: pan0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN
  link/ether b6:50:83:8a:65:19 brd ff:ff:ff:ff:ff:ff
7: tap0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 500
  link/ether fe:b5:c8:70:b2:5f brd ff:ff:ff:ff:ff:ff
  inet 192.168.100.1/24 brd 192.168.100.255 scope global tap0
  inet6 fe80::fcb5:c8ff:fe70:b25f/64 scope link
    valid_lft forever preferred_lft forever

192.168.100.0/24 dev tap0 proto kernel scope link src 192.168.100.1
192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.3
default via 192.168.0.1 dev eth0

[ukchucktown]

Re: Routing help

Well, maybe the answer isn't so simple. :P

QUICK UPDATE...

I managed to get something working with the help of firestarter. I never got it working myself. I was able to tell the firestarter wizard what I wanted and it did the right thing. I had to ditch the network managers and manually configure the interfaces. I could not get firestarter to play nice with wicd. I never investigated since my network configuration is pretty convoluted - manual was my best option. I purged network-manager and wicd, configured manually, installed firestarter and ran the wizard.

I noticed one new entry in my routing table after configuring firestarter, the 169.254.x.x line. I'm still trying to reverse engineer what firestarter did to my system because I still don't fully understand everything, but it works, which is pretty cool. I can now ping outside addresses from the private network running inside virtualbox. I'm using bridged networking through a tap interface. It's not perfect yet, firestarter is blocking some services from the windows servers, but at least it works.

estination Gateway Genmask Flags Metric Ref Use Iface
192.168.100.0 0.0.0.0 255.255.255.0 U 0 0 0 tap0
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 tap0
0.0.0.0 192.168.0.1 0.0.0.0 UG 100 0 0 eth0