Hey folks,

So, I'm a bit confused here, so bear with me. My issue is that on my network I have a small home/office router/switch and it currently is set to provide DNS services.

My issue is that I although I can get Windows to resolve the hostname of my Ubuntu Server LTS 10.04 box, I can't get the Ubuntu server to resolve the Windows clients. Why is this the case?

I have a feeling that the nmbd process is advertising the NetBIOS name of the Linux server for Windows machines to resolve, but there is no way for Linux to resolve the NetBIOS names of the incoming clients. This forces me to use IP addresses instead of the client names.

I found an article that explained that the winbind package is needed for the Linux server to recognize NetBIOS names, but can this not be accomplished by setting my router as the primary DNS in the /etc/resolv.conf file? I added the IP address of the router to /etc/resolv.conf, but I still can't reach the client machine using its NetBIOS name even though it shows up on the client list provided by the router's DNS table.

What am I missing here?

Also, as a side note, is there a utility that opertates like the Windows Network Neighbourhood, whereby a Linux Server list all visible clients on the network? i.e. list all available hosts that it can connect to?

Thanks!

Hi Syllinger,

Appears that Ubuntu system is unaware about the DNS and thus it is not able to resolve name of your Windows system. Try the following:

1. Open up command prompt on Windows machine.
2. Type nslookup
3. Once you are in nslookup up type "server" without quotes. It should show you the IP or hostname of your DNS server.
4. Do the same on your Ubuntu machine. Open up terminal and get into nslookup.
5. Type server and it should show you the name or IP of your dns server.

If the IP or hostname of DNS server matches on both machines then something is wrong with DNS server because DNS should resolve the name.

If not, then your Ubuntu machine is totally unaware of DNS server and you have to configure its interface to use the DNS server which is used by your Windows machine.

Hard to answer w/o knowing the router, and what kind of set-up for DNS
it can handle. You need to understand first and foremost that DNS and
winbind are orthogonal to each other. Because windows wants (needs) to
be able to also reach machines via plain IP it is bound to do name-lookups
the good old-fashioned DNS way. The reverse is not true.

And just because your router has some knowledge of your windows
machines names (you sure it's a DNS table, not a DHCP one?) doesn't
necessarily mean that it passes these names on via DNS - again, I don't
know make or model of your router.

To make things "easy" (I know, that's a relative term ;}) you may want
to consider to make your Linux box a DNS & DHCP server for your internal
network.


Cheers,
Tink

Hey T3RM1NVT0R, thanks for the reply.

I have two nameserver entries in /etc/resolv.conf, but the priority is the router which is 10.0.0.1. The only difference I see between the ouput is that on the Windows client this information is listed as:

Server: my.router
Address: 10.0.0.1

While on the Ubuntu Server the output is:

Default server: 10.0.0.1
Address: 10.0.0.1#53

It's the #53 part that's concerning me...I have never seen that.

Port 53 is the port DNS server uses. So that is normal.

If it shows the same server IP then both the systems are using the same DNS server.

Now perform the following test on both the machines:

1. Open up nslookup and type the following commands.
2. set debug
3. hostname (If doing from ubuntu type in Windows host name and if doing it from Windows type in ubuntu hostname)
4. Paste the output here. The output should contain the query being asked to DNS server and the reply it is giving.

On Linux:

Name: rome
Address: 8.15.7.107
Name: rome
Address: 63.251.179.17


On Windows the request timed out.

I have a feeling that the router doesn't actually have DNS capability as I originally thought. Based on the IP that the Linux server produced it looks like it's forwarding the request to the ISP DNS server and simply acting as an intermediary.

I'm using the ASUS RT-N56U, and after reading a few posts, I don't believe it has DNS capability.

I may opt to do what Tinkster suggested, but I'll keep my router as the DHCP server and run DNS services on the Linux server. That said, I don't want to expose the server directly to the internet. If I were to use this approach, if the server can't find the hostname that is queried, will it not then query the ISP's DNS servers to see if it can fidn a match there?

I want to keep security as tight as possible.

My goal was to separate the entire network from the internet via the router. But it seems that may not be possible now.

Yes go with the tinkster's suggestion. If there are not many hosts in your network then you can use /etc/hosts file to populate hostnames.

Please mark the thread as solved if you think you got the solution to your query.

Syllinger,
Don't worry about your Linux box making recursive queries outbound to DNS servers; that's what DNS is supposed to do. If you have an ISP's gateway router installed, that probably firewalls incoming traffic except that which you have explicitly allowed. Unless you've poked a pinhole in the CPE router/firewall for DNS, Internet clients will not be able to get information about your internal address space. You can log into the web interface for the router and make sure.

His problem is that the windows machines on his LAN don't
resolve. His ISP won't help him much with that, neither will
DNS forwarding, or a pinhole. He needs to stand up DNS on
his Linux box, and that's that.


Cheers,
Tink