I hope someone can point me in the right direction here. All I'm attempting to do is set up Ubuntu Desktop 8.04 as a Transparent Proxy. I've done all the work on the proxy and that's working fine. I want to be able to communicate with the DNS Servers on eth0 from clients on the eth1 interface.
But I can't figure out how Ubuntu routes traffic
Here's my test network:
Client PC 192.168.40.40/23 (DG: 192.168.30.3 DNS: 192.168.10.10)
L Ubuntu eth1 192.168.40.3/23
Ubuntu eth0 192.168.10.50/23 (DG: 192.168.10.1 DNS: 192.168.10.10)
L DNS Server 192.168.10.10
I've tried setting: net.ipv4.ip_forward=1 in /etc/sysctl.conf as I thought this should pass traffic forward.
I've looked at IP Tables but this looks just like a Firewall and not a router?
Any help would be great?
Last edited by jimothy; 9th May 2008 at 01:09 PM.
I would have thought that the server version of Ubuntu would have been a better choice.
Only my opinion, so don't shoot me.
whats the output of
Thanks for the replies
@ dhicks. I thought about that, installing BIND, but I thought it may confuse matters more? If possible I could do that but how do I ensure that DNS is published on the eth1 interface and not on the eth0?
@CyberNerd: The routing table looks like this:
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
192.168.10.0 0.0.0.0 255.255.254.0 U 0 0 0 eth0
192.168.40.0 0.0.0.0 255.255.254.0 U 0 0 0 eth1
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth1
0.0.0.0 192.168.10.1 0.0.0.0 UG 0 0 0 eth0
Yeah, should be. I changed the subnet which the eth1 was on as I've already got a VLAN on the eth0 side which is already on 192.168.30.0/23.
I wanted to ensure that there was no weird routing going on.
Run a caching DNS server on your Ubuntu box. Point the clients behind the ubuntu box at that.
Cheers Geoff, any good HowTo's on DNS Caching?
A default install of bind9 from the repo leaves it configured as a caching DNS server, just configure the forwarders.
Installed BIND9 and left as default. Configured DNS forwarders: 192.168.10.10.
Clients on the eth1 interface pick up DHCP with 192.168.40.3 as their DG and DNS server.
Still no DNS resolution for clients.
And what does bind think is going on?
Not sure how to pull out BIND config, but if this is any help:
/etc/resolve.conf has: servername 192.168.10.10 specified.
I can dig 127.0.0.1 from the Ubuntu box and it shows it's using 192.168.10.10:53 to resolve the address.
I'd imagine the log files are in /var/log/bind/ the configuration will be hiding in /etc/bind/
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