Ubuntu getting wrong hostname from DHCP
- by sam
When provisioning new Ubuntu Precise (12.04) servers, the hostname they're getting seems to be generated from the DNS search path, not a reverse lookup on the hostname.
Take the following configuration
BIND is configured with the hostname, and reverse name
Normal zone
$TTL 600
$ORIGIN srv.local.net.
@ IN SOA ns0.local.net. hostmaster.local.net. (
2014082101
10800
3600
604800
600 )
@ IN NS ns0.local.net.
@ IN MX 5 mail.local.net.
my-new-server IN A 10.32.2.30
And reverse
@ IN SOA ns0.local.net. hostmaster.local.net. (
2014082101
10800
3600
604800
600 )
@ IN NS ns0.local.net.
$ORIGIN 32.10.in-addr.arpa.
30.2 IN PTR my-new-server.srv.local.net.
Then DHCPD is configured to hand out static leases based on mac addresses like so
subnet 10.32.2.0 netmask 255.255.254.0 {
option subnet-mask 255.255.254.0;
option routers 10.32.2.1;
option domain-name-servers 10.32.2.1;
option domain-name "util.of1.local.net of1.local.net srv.local.net";
site-option-space "pxelinux";
option pxelinux.magic f1:00:74:7e;
if exists dhcp-parameter-request-list {
option dhcp-parameter-request-list = concat(option dhcp-parameter-request-list,d0,d1,d2,d3);
}
group {
option pxelinux.configfile "pxelinux.cfg/pxeboot";
host my-new-server {
fixed-address my-new-server.srv.local.net;
hardware ethernet aa:aa:aa:bb:bb:bb;
}
}
}
So the hostname should be my-new-server.srv.local.net, however when building a Ubuntu 12.04 node, the hostname ends up as my-new-server.util.of1.local.net
When building Lucid (10.04) hosts, the hostname will be correct, it's only on Precise/12.04 nodes we have the problem.
Doing a normal and reverse lookup on the host and IP returns the correct result
Sams-MacBook-Pro:~ sam$ host my-new-server
my-new-server.srv.local.net has address 10.32.2.30
Sams-MacBook-Pro:~ sam$ host my-new-server.srv.local.net
my-new-server.srv.local.net has address 10.32.2.30
Sams-MacBook-Pro:~ sam$ host 10.32.2.30
30.2.32.10.in-addr.arpa domain name pointer my-new-server.srv.local.net.
The contents of the hosts file is incorrect too
127.0.0.1 localhost
127.0.1.1 my-new-server.util.of1.local.net of1.local.net srv.local.net my-new-server
So it looks like when it creates the hosts file, it puts the entire contents of the DNS search path into the local address so the FQDN according to the server is the short hostname as defined, then the first domain in the search path.
Is there a way to get around this behaviour, or fix this so it gets the hostname correctly? It's picking up the first part of the hostname, then the rest is wrong.
