FAQ Search Today's Posts Mark Forums Read
» Video Reviews

» Linux Archive

Linux-archive is a website aiming to archive linux email lists and to make them easily accessible for linux users/developers.


» Sponsor

» Partners

» Sponsor

Go Back   Linux Archive > CentOS > CentOS

 
 
LinkBack Thread Tools
 
Old 05-02-2012, 09:35 PM
Adrian Constantin
 
Default Incomplete host name resolution

Hello

I happen to have two network interfaces on my new, up-to-date, CentOS
6.2, named eth0 and virbr0 (3 of them if I include the lo interface).

However the system APIs like getaddrinfo() only return the address for
the virbr0 interface (which was created by the CentOS installation),
when I would like to have them both.

Even if I give the configured eth0 address explicitly to getnameinfo(),
it can not perform the reverse lookup to my hostname, and returns a
string with the same numeric IP address given as argument. I also can
not get the list of samba name aliases for my host name.

I can happily ping my host from a different computer on the eth0
network, so the nmb service binds on eth0 and works as expected.

I have installed and configured smb, nmb and winbind services, and I
have added 'wins' to /etc/nsswitch.conf, so my hosts line there looks like:
hosts: files wins mdns4_minimal [NOTFOUND=return] dns

Is there something I should do for wins name service to return all IP
addresses ?

Are there some similar settings that I need to do in order to get the
reverse lookup to work ?

For reference here are my system information and application output, as
follows.

Here are my interfaces:
[adrian@adrian projects]$ ifconfig
eth0 Link encap:Ethernet HWaddr 00:1C:C0A:63:75
inet addr:10.0.0.154 Bcast:10.255.255.255 Mask:255.0.0.0
inet6 addr: fe80::21c:c0ff:feda:6375/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1222539 errors:0 dropped:0 overruns:0 frame:0
TX packets:708669 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1491421614 (1.3 GiB) TX bytes:136206085 (129.8 MiB)
Interrupt:20 Memory:d0600000-d0620000

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:751048 errors:0 dropped:0 overruns:0 frame:0
TX packets:751048 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:208785657 (199.1 MiB) TX bytes:208785657 (199.1 MiB)

virbr0 Link encap:Ethernet HWaddr 52:54:00:92:B0:1A
inet addr:192.168.122.1 Bcast:192.168.122.255
Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:4038 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:393067 (383.8 KiB)

And here is how my applications behave:
[adrian@adrian projects]$ python
Python 2.6.6 (r266:84292, Dec 7 2011, 20:48:22)
[GCC 4.4.6 20110731 (Red Hat 4.4.6-3)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import socket
>>> socket.gethostbyname_ex('adrian')
('adrian', [], ['192.168.122.1'])
>>> for a in socket.getaddrinfo('adrian', None, 0, 0, 0,
socket.AI_CANONNAME) :
... print a
...
(2, 1, 6, 'adrian', ('192.168.122.1', 0))
(2, 2, 17, ', ('192.168.122.1', 0))
(2, 3, 0, ', ('192.168.122.1', 0))
>>>
[adrian@adrian projects]$

As you can see there are no name aliases returned, and there is only one
IP address given for my host name.

You can see my samba name aliases here:
[adrian@adrian projects]$ nmblookup -A -T 10.0.0.154
Looking up status of 10.0.0.154
ADRIAN <00> - B <ACTIVE>
ADRIAN <03> - B <ACTIVE>
ADRIAN <20> - B <ACTIVE>
..__MSBROWSE__. <01> - <GROUP> B <ACTIVE>
TERMINATORUL <00> - B <ACTIVE>
TERMINATORUL <03> - B <ACTIVE>
TERMINATORUL <20> - B <ACTIVE>
TIMOTHY <00> - B <ACTIVE>
TIMOTHY <03> - B <ACTIVE>
TIMOTHY <20> - B <ACTIVE>
TOUGHY <00> - B <ACTIVE>
TOUGHY <03> - B <ACTIVE>
TOUGHY <20> - B <ACTIVE>
WORKGROUP <1d> - B <ACTIVE>
WORKGROUP <1e> - <GROUP> B <ACTIVE>
WORKGROUP <00> - <GROUP> B <ACTIVE>

MAC Address = 00-00-00-00-00-00

(namely adrian, terminatorul, timothy, toughy).
Trying to resolve my hostname to an IP address with nmblookup also
returns just one of the IP addresses:

[adrian@adrian projects]$ nmblookup adrian
querying adrian on 192.168.122.255
192.168.122.1 adrian<00>
[adrian@adrian projects]$

_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 

Thread Tools




All times are GMT. The time now is 12:13 PM.

VBulletin, Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO ©2007, Crawlability, Inc.
Copyright 2007 - 2008, www.linux-archive.org