*nix Thread, Ubuntu Routing in Technical; Hi there,
I hope someone can point me in the right direction here. All I'm attempting to do is set ...
8th May 2008, 05:21 PM #1
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.
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8th May 2008, 07:20 PM #2
Do you need to run a DNS server on your filtering machine that deals with requests on eth1 and uses the DNS server available on eth0 as its parent server?
Originally Posted by jimothy
8th May 2008, 07:30 PM #3
I would have thought that the server version of Ubuntu would have been a better choice.
Only my opinion, so don't shoot me.
8th May 2008, 08:48 PM #4
9th May 2008, 10:26 AM #5
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
9th May 2008, 01:04 PM #6
Shouldn't that second line be:
Originally Posted by jimothy
192.168.30.0 0.0.0.0 255.255.254.0 U 0 0 0 eth1
9th May 2008, 01:09 PM #7
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.
9th May 2008, 01:36 PM #8
Run a caching DNS server on your Ubuntu box. Point the clients behind the ubuntu box at that.
9th May 2008, 03:27 PM #9
Cheers Geoff, any good HowTo's on DNS Caching?
9th May 2008, 03:50 PM #10
A default install of bind9 from the repo leaves it configured as a caching DNS server, just configure the forwarders.
9th May 2008, 04:05 PM #11
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.
9th May 2008, 04:07 PM #12
And what does bind think is going on?
9th May 2008, 05:05 PM #13
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.
10th May 2008, 04:51 PM #14
I'd imagine the log files are in /var/log/bind/ the configuration will be hiding in /etc/bind/
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