15

I've got 2 machines on the same sub-net running Debian 5.0. They use the same DNS (/etc/resolv.conf), they route to the same gateway (#route) and they have the same iptables settings (#iptables -L). I can ping from both of them, both to IP addresses and to host names. I can run #host www.google.com and get the same results on both of them. But the problem is that on one of them, I can't wget or curl.

So on machine 1 everything is OK, but on machine 2 (with the same settings as machine 1) I can't wget or curl.

The error I get is:

# wget google.com
--2009-10-20 16:38:36--  http://google.com/
Resolving google.com... failed: Name or service not known.
wget: unable to resolve host address `google.com'

But on machine 1 it has no problem to wget or curl and returns:

# wget google.com
--2009-10-20 16:43:55--  http://google.com/
Resolving google.com... 74.125.53.100, 74.125.45.100, 74.125.67.100
Connecting to google.com|74.125.53.100|:80... connected.
HTTP request sent, awaiting response... 301 Moved Permanently
...
Saving to: `index.html.3'

Etc.

I'm hoping someone here can point me in the right direction here so that I can possibly fix this issue :)

3
  • 1
    This is most probably not related to wget but to a networking issue.
    – jldupont
    Commented Oct 20, 2009 at 16:43
  • do you have a proxy setting in the environment .. my work machine did :-(
    – lexu
    Commented Oct 20, 2009 at 16:44
  • Try "host google.com", not "host www.google.com", on server 2.
    – Bill Weiss
    Commented Oct 20, 2009 at 17:43

5 Answers 5

22

Check your /etc/nsswitch.conf file (or whatever the equivalent is on Debian if it's not that).

host and nslookup always do DNS lookups.

However other applications will look in NSS first for other naming systems (e.g. /etc/hosts, NIS, etc). If something else is configured but not working it could prevent the application from ever trying the DNS.

1
  • 3
    The canonical way to check the resolver is running getent hosts google.com. This uses nsswitch.conf and then resolv.conf as required.
    – Joe
    Commented Nov 5, 2009 at 19:08
13

Thanks for the answers you guys!

It was the nsswitch.conf file. I had setup LDAP from a tutorial that told me to use this line in hosts:

hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4

When I changed it to this:

hosts: files dns mdns4_minimal [NOTFOUND=return] mdns4

It works without a problem. So I guess the nsswitch config file was making it return null if not found in files or mdns4_minimal, right?

Thanks for your help!

3
  • 8
    You should probably accept Alnitak's answer.
    – Dan Carley
    Commented Oct 21, 2009 at 13:23
  • Yeah, how do I do that? :-/
    – Maggi Trymbill
    Commented Oct 26, 2009 at 21:08
  • Accept by clicking the "V" next to the vote score. :)
    – Redsandro
    Commented Mar 31, 2013 at 21:36
4

I had the same problem, but next to changing /etc/nsswitch.conf:

hosts: files dns mdns4_minimal [NOTFOUND=return] mdns4

I also had to change the name servers:

Change /etc/resolv.conf so it points to the google nameservers. The ones added by network manager don't work for me.

# RED 2013-03-31
nameserver 8.8.8.8
nameserver 8.8.4.4
1
  • 3
    Thanks, anonymous, for the constructive comment on the downvote.
    – Redsandro
    Commented Sep 23, 2014 at 11:21
3

Could there be an invalid proxy configured on the machine with the error? Try this:

# wget --no-proxy google.com
3

The first thing to try is checking whether DNS works correctly.

# host google.com
google.com has address 74.125.67.100
google.com has address 74.125.45.100
google.com has address 74.125.53.100

If you don't get that response, check /etc/resolv.conf and find the name servers listed in that file. Can you ping each of them?

Try querying each of them individually:

# host google.com 12.34.56.78

Can you resolve another host?

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