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# Authentication on PostgreSQL

### PostgreSQL Roles and Authentication Methods

PostgreSQL handles database access permissions using the concept of roles. Depending on how you set up the role, it can represent a database user or a group of database users.

PostgreSQL supports several authentication methods . The most frequently used methods are:

* <mark style="color:orange;">`Trust`</mark> - A role can connect without a password, as long as the criteria defined in the <mark style="color:orange;">`pg_hba.conf`</mark> are met
* <mark style="color:orange;">`Password`</mark> - A role can connect by providing a password. The passwords can be stored as scram-sha-256 md5 and password (clear-text)
* <mark style="color:orange;">`Ident`</mark> - Only supported for TCP/IP connections. It works by obtaining the client’s operating system user name, with an optional user name mapping.
* <mark style="color:orange;">`Peer`</mark> - Same as Ident, but it is only supported on local connections.

PostgreSQL client authentication is defined in the configuration file named <mark style="color:orange;">`pg_hba.conf`</mark>. For local connections, PostgreSQL is set to use the peer authentication method.

The **“**<mark style="color:orange;">**postgres**</mark>**”** user is automatically created when PostgreSQL is installed. This user is the superuser for the PostgreSQL instance, and it is equivalent to the MySQL <mark style="color:orange;">`root`</mark> user.

To log in to the PostgreSQL server as **“**<mark style="color:orange;">**postgres**</mark>**”**, switch to the user postgres and access a PostgreSQL prompt using the <mark style="color:orange;">`psql`</mark> utility:

```bash
sudo su - postgres
psql
```

To Exit:

```bash
\q
```

You can use the sudo command to access the PostgreSQL prompt without switching users:

```bash
sudo -u postgres psql
```

*The <mark style="color:orange;">`postgres`</mark> user is typically used only from the <mark style="color:orange;">`localhost`</mark>*