Thread: postgres 9.0 - unable to bind to localhost.

postgres 9.0 - unable to bind to localhost.

From

"Rajagopalan, Jayashree"

Date:

10 December 2012, 11:58:10

Hi all:

Getting this error in the postgres logs:

2012-11-29 09:47:39.335 CST - SessionId:50b7839b.4791 - TransId:0 - LOG: could not translate host name "localhost", service "5435" to address: Name or service not known

2012-11-29 09:47:39.336 CST - SessionId:50b7839b.4791 - TransId:0 - WARNING: could not create listen socket for "localhost"

2012-11-29 09:47:39.343 CST - SessionId:50b7839b.4791 - TransId:0 - LOG: could not resolve "localhost": Name or service not known

Also the netstat command reveals the port(5435) is not bound to 127.0.0.1.
Checked the pg_hba.conf, /etc/hosts, nsswitch.conf, resolv.conf do not see any issues there.

the listen_addresses entry is like this:

listen_addresses = 'localhost,<host_ip>'

The port is bound to the <host_ip> but not to localhost.

How does postgres resolve the local host?

The entry is proper for localhost in /etc/hosts, and nsswitch.conf points hosts to files, dns.

"host localhost" resolves to 127.0.0.1 in command line.

what else to check?

Regards

Re: postgres 9.0 - unable to bind to localhost.

From

Strahinja Kustudić

Date:

23 December 2012, 14:39:02

Sorry for a late reply, but I had the exact same problem and it was a bug in the Red Hat RPM package upgrade script of the sudo package. This basically means the user running Postgres cannot resolve hostname localhost. Have you tried logging in as the user running Postgres and trying to resolve localhost? In RHEL/Centos you would do this with:

su - postgres

nslookup localhost

If this returns 127.0.0.1, then something else is a problem, but if it says the hostname cannot be resolved, then you need to check permissions of /etc/hosts and /etc/nsswitch.conf, all users should be able to read those two files. You can just run:

chmod a+r /etc/hosts

chmod a+r /etc/nsswitch.conf

Another workaround would be to replace 'localhost' in postgresql.conf with '127.0.0.1'.

Regards,

Strahinja

On Mon, Dec 10, 2012 at 9:57 AM, Rajagopalan, Jayashree <Jayashree.Rajagopalan@emc.com> wrote:

Hi all:

Getting this error in the postgres logs:
2012-11-29 09:47:39.335 CST - SessionId:50b7839b.4791 - TransId:0 - LOG: could not translate host name "localhost", service "5435" to address: Name or service not known
2012-11-29 09:47:39.336 CST - SessionId:50b7839b.4791 - TransId:0 - WARNING: could not create listen socket for "localhost"
2012-11-29 09:47:39.343 CST - SessionId:50b7839b.4791 - TransId:0 - LOG: could not resolve "localhost": Name or service not known

Also the netstat command reveals the port(5435) is not bound to 127.0.0.1.
Checked the pg_hba.conf, /etc/hosts, nsswitch.conf, resolv.conf do not see any issues there.

the listen_addresses entry is like this:

listen_addresses = 'localhost,<host_ip>'

The port is bound to the <host_ip> but not to localhost.

How does postgres resolve the local host?

The entry is proper for localhost in /etc/hosts, and nsswitch.conf points hosts to files, dns.

"host localhost" resolves to 127.0.0.1 in command line.

what else to check?

Regards
J

Re: postgres 9.0 - unable to bind to localhost.

From

"Gunnar \"Nick\" Bluth"

Date:

31 January 2013, 00:19:10

Am 23.12.2012 12:38, schrieb Strahinja Kustudić:

Sorry for a late reply, but I had the exact same problem and it was a bug in the Red Hat RPM package upgrade script of the sudo package. This basically means the user running Postgres cannot resolve hostname localhost. Have you tried logging in as the user running Postgres and trying to resolve localhost? In RHEL/Centos you would do this with:

su - postgres
nslookup localhost

A late comment on this one... but I've learnt this lesson the hard way :/
If you want to know what am actual program will get, use "getent hosts <hostname/IP>", that will follow the directions in nsswitch.conf and also use an nscd, if you're running one.

So, if someone (for whatever reason) once put a line
1.2.3.4 localhost
in your /etc/hosts, the "nslookup" will return what you'd expect (i.e., hopefully ;-), but Postgres will try to open a socket on 1.2.3.4. Bang!

Apart from that:
a) nslookup is deprecated since ages, use "host" or "dig" (well, no, use "getent hosts" ;-)
b) I doubt that all DNS possible servers (M$ ones spring to mind...) will provide answers to "localhost"

Just my 2p...

-- 
Gunnar "Nick" Bluth
RHCE/SCLA

Mobil   +49 172 8853339
Email: gunnar.bluth@pro-open.de
__________________________________________________________________________
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