psql: error: connection to server on socket "/var/run/postgresql/.s.PGSQL.5432" failed: FATAL: Peer authentication failed for user "postgres" (Ubuntu)

Question

When I try to open psql with this command:

psql -U postgres

I get this error:

psql: error: connection to server on socket "/var/run/postgresql/.s.PGSQL.5432" failed: FATAL:  Peer authentication failed for user "postgres"

But it connects successfully when I use:

sudo -u postgres psql

Can someone please explain what is happening and how to diagnose/fix this problem? My pg_hba.conf contains the following:

# Database administrative login by Unix domain socket
local   all             postgres                                peer

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     md5
# IPv4 local connections:
host    all             all             127.0.0.1/32            scram-sha-256
# IPv6 local connections:
host    all             all             ::1/128                 scram-sha-256
# Allow replication connections from localhost, by a user with the
# replication privilege.
local   replication     all                                     peer

Answer 1

Peer authentication means that the connection is only allowed if the name of the database user is the same as the name of the operating system user.

So if you run psql -U postgres as operating system user root or jimmy , it won't work.

You can specify amapping between operating system users and database users in pg_ident.conf .

Answer 2

You can edit your .conf files with privileges using an editor, for my case it is nano.

$sudo nano /etc/postgresql/14/main/pg_ident.conf

Map your user by adding this line

# MAPNAME       SYSTEM-USERNAME         PG-USERNAME
user1             <computer-username>               postgres

Replace the <computer-username> with the System-Username, which can be found using the whoami command. Type in your terminal:

$whoami

Then go ahead to the pg_hba.conf

$sudo nano /etc/postgresql/14/main/pg_hba.conf

Add your postgre user, with method=peer, as shown below:

# TYPE  DATABASE        USER            ADDRESS                 METHOD
local   all             postgres                                peer

This worked for me.

Answer 3

 step-1 vi /etc/postgresql/14/main# vi postgresql.conf listen_addresses = '*' step-2 vi /etc/postgresql/14/main# vi pg_hba.conf # Database administrative login by Unix domain socket local all postgres peer # TYPE DATABASE USER ADDRESS METHOD # "local" is for Unix domain socket connections only local all all md5 # IPv4 local connections: host all all 0.0.0.0/0 scram-sha-256 # IPv6 local connections: host all all::1/128 scram-sha-256 # Allow replication connections from localhost, by a user with the # replication privilege. local replication all peer step-3 sudo /etc/init.d/postgresql restart step-4 After restart your changes create your required database and database username

Answer 4

I don't think in production you wana bother yourself changing any files.
So, What you can do is temporarily make the username same to the username of your postgres which is usually postgres by passing command sudo -i -u postgres and then psql , now you successfully connected to postgres.