could not connect to database postgres: could not translate host name "p1" to address: Temporary failure in name resolution createuser: could not connect to database postgres: FATAL: no pg_hba.conf entry for host "192.168.2.1", user "postgres", database "postgres", SSL off

could not connect to database postgres: could not translate host name "p1" to address: Temporary failure in name resolution

createuser: could not connect to database postgres: FATAL:  no pg_hba.conf entry for host "192.168.2.1", user "postgres", database "postgres", SSL off

-bash-3.2$ ./createuser -h p1 -p 5432 -D -A -e u7
createuser: could not connect to database postgres: could not translate host name "p1" to address: Temporary failure in name resolution

solution:

step 1:put the entries of host information on host file

-bash-3.2# cat  /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1     localhost.localdomain localhost
192.168.2.1 p1.postgresql786.com p1

step 2:restart the network adapter

-bash-3.2# service network restart
Shutting down interface eth0:                              [  OK  ]
Shutting down loopback interface:                          [  OK  ]
Bringing up loopback interface:                            [  OK  ]
Bringing up interface eth0:                                [  OK  ]

-bash-3.2# ping p1
PING p1.postgresql786.com (192.168.2.1) 56(84) bytes of data.
64 bytes from p1.postgresql786.com (192.168.2.1): icmp_seq=1 ttl=64 time=1.46 ms

--again run the command 

-bash-3.2$ ./createuser -h p1 -p 5432 -D -A -e u7
createuser: could not connect to database postgres: FATAL:  no pg_hba.conf entry for host "192.168.2.1", user "postgres", database "postgres", SSL off

solution :

step1. put the hostname & ip address entries in pg_hba.conf file

-bash-3.2# vi /opt/PostgreSQL/9.3/data/pg_hba.conf
host   all              all             192.168.2.1/32           md5
 :wq

step 2.restart the postgres server 

-bash-3.2# /etc/init.d/postgresql-9.3  restart
Restarting PostgreSQL 9.3: 
waiting for server to shut down.... done
server stopped
waiting for server to start.... done
server started
PostgreSQL 9.3 restarted successfully

--Run the command again user will be created succesfully

-bash-3.2$ ./createuser -h p1 -p 5432 -D -A -e u7
Password: 
CREATE ROLE u7 NOSUPERUSER NOCREATEDB NOCREATEROLE INHERIT LOGIN;

--Check the user:

postgres=# \du 
                             List of roles
 Role name |                   Attributes                   | Member of 
-----------+------------------------------------------------+-----------
 nijam     |                                                | {}
 postgres  | Superuser, Create role, Create DB, Replication | {}
 rep       | Replication                                   +| {}
           | 1 connection                                   | 
 u1        |                                                | {}
 u2        |                                                | {}
 u3        | Password valid until 2017-06-06 00:00:00-04    | {}
 u4        | Create DB                                      | {}
 u5        |                                                | {}
 u6        |                                                | {}
 u7        |                                                | {}                                            

postgres=# select usename,passwd,valuntil,usecreatedb from PG_SHADOW;                          
 usename  |               passwd                |        valuntil        | usecreatedb 
----------+-------------------------------------+------------------------+-------------
 postgres | md505ea766c2bc9e19f34b66114ace97598 |                        | t
 rep      | md5df2c887bcb2c49b903aa33bdbc5c2984 |                        | f
 u1       |                                     |                        | f
 u2       | u2                                  |                        | f
 u3       | md5dad1ef51b879799793dc38d714b97063 | 2017-06-06 00:00:00-04 | f
 nijam    |                                     |                        | f
 u4       | md54af10c3137cf79c12265e8d288070711 |                        | t
 u5       |                                     |                        | f
 u6       |                                     |                        | f
 u7       |                                     |                        | f
(10 rows)