Setting up Kerberos authentication¶

This document provides configuration steps for setting up Kerberos Authentication in Percona Server for MongoDB.

Assumptions¶

The setup of the Kerberos server itself is out of scope of this document. Please refer to the Kerberos documentation for the installation and configuration steps relevant to your operation system.

We assume that you have successfully completed the following steps:

Installed and configured the Kerberos server
Added necessary realms
Added service, admin and user principals
Configured the A and PTR DNS records for every host running mongod instance to resolve the hostnames onto Kerberos realm.

Add user principals to Percona Server for MongoDB¶

To get authenticated, users must exist both in the Kerberos and Percona Server for MongoDB servers with exactly matching names.

After you defined the user principals in the Kerberos server, add them to the $external database in Percona Server for MongoDB and assign required roles:

> use $external
> db.createUser({user: "demo@PERCONATEST.COM",roles: [{role: "read", db: "admin"}]})

Replace demo@PERCONATEST.COM with your username and Kerberos realm.

Configure Kerberos keytab files¶

A keytab file stores the authentication keys for a service principal representing a mongod instance to access the Kerberos admin server.

After you have added the service principal to the Kerberos admin server, the entry for this principal is added to the /etc/krb5.keytab keytab file.

The mongod server must have access to the keytab file to authenticate. To keep the keytab file secure, restrict the access to it only for the user running the mongod process.

Stop the mongod service
```
$ sudo systemctl stop mongod
```
Generate the keytab file or get a copy of it if you generated the keytab file on another host. Save the keyfile under a separate path (e.g. /etc/mongodb.keytab)
```
$ cp /etc/krb5.keytab /etc/mongodb.keytab
```

Change the ownership to the keytab file

$ sudo chown mongod:mongod /etc/mongodb.keytab

Set the KRB5_KTNAME variable in the environment file for the mongod process.
Debian and UbuntuRHEL and derivatives
Edit the environment file at the path /etc/default/mongod and specify the KRB5_KTNAME variable:
KRB5_KTNAME=/etc/mongodb.keytab
If you have a different path to the keytab file, specify it accordingly.
Edit the environment file at the path /etc/sysconfig/mongod and specify the KRB5_KTNAME variable:
KRB5_KTNAME=/etc/mongodb.keytab
If you have a different path to the keytab file, specify it accordingly.
Restart the mongod service
```
$ sudo systemctl start mongod
```

Percona Server for MongoDB configuration¶

Enable external authentication in Percona Server for MongoDB configuration. Edit the etc/mongod.conf configuration file and specify the following configuration:

security:
  authorization: "enabled"

setParameter:
  authenticationMechanisms: GSSAPI

Restart the mongod service to apply the configuration:

$ sudo systemctl start mongod

Test the access to Percona Server for MongoDB¶

Obtain the Kerberos ticket for the user using the kinit command and specify the user password:
```
$ kinit demo
Password for demo@PERCONATEST.COM:
```

Check the user ticket:

$ klist -l

Output:

Principal name                 Cache name
--------------                 ----------
demo@PERCONATEST.COM           FILE:/tmp/<ticket>

Connect to Percona Server for MongoDB:

$ mongo --host <hostname> --authenticationMechanism=GSSAPI --authenticationDatabase='$external' --username demo@PERCONATEST.COM

The result should look like the following:

> db.runCommand({connectionStatus : 1})
{
     "authInfo" : {
             "authenticatedUsers" : [
                     {
                             "user" : "demo@PERCONATEST.COM",
                             "db" : "$external"
                     }
             ],
             "authenticatedUserRoles" : [
                     {
                             "role" : "read",
                             "db" : "admin"
                     }
             ]
     },
     "ok" : 1
}

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Last update: January 31, 2023
Created: December 8, 2022