Redis setup

The Redis setup is well documented on their site http://redis.io. The TURN Server Redis database schema description can be found in schema.userdb.redis and schema.stats.redis files. Those files are located either in the turndb subdirectory of the main source code directory, or in /usr/local/share/turnserver/ after the installation, or somewhere in /usr/share/ directory, depending on the OS and on the installation package.

If the TURN server was compiled with Hiredis support (Hiredis is the C client library for Redis), then we can use the TURN server database parameter --redis-userdb. The value of this parameter is a connection string for the Redis database. As "native" Redis does not have such a feature as "connection string", the TURN server parses the connection string and converts it into Redis database access parameter. The format of the Redis connection string is:

"ip=<ip-addr> dbname=<database-number> password=<database-password> port=<port> connect_timeout=<seconds>"

(all parameters are optional)

So, an example of the Redis database parameter in the TURN server command line would be:

--redis-userdb="ip=127.0.0.1 dbname=2 password=turn connect_timeout=30"

Or in the turnserver.conf file:

redis-userdb="ip=127.0.0.1 dbname=2 password=turn connect_timeout=30"

TLS / SSL connections to Redis

By default the TURN server talks to Redis over plaintext TCP. If your Redis server is configured to accept TLS connections (Redis tls-port, see https://redis.io/docs/management/security/encryption/), the connection string can request a TLS transport. This requires the TURN server to have been built against the hiredis_ssl library (the TLS companion to Hiredis); if it was not, tls=true is rejected with an explicit error at connection time.

The TLS-related connection-string keys are:

Key	Aliases	Meaning
`tls=true`	`ssl`	Enable TLS for this connection (`true/1/on/yes`).
`ca=<file>`	`cacert`, `tls-ca`	CA certificate/bundle used to verify the server.
`capath=<dir>`	`tls-capath`	Directory of CA certificates (OpenSSL hashed layout).
`cert=<file>`	`tls-cert`	Client certificate file (mutual TLS).
`clientkey=<file>`	`tls-key`	Client private key file (mutual TLS).
`sni=<name>`	`servername`, `tls-sni`	Server name for SNI and certificate verification (defaults to the host).
`verify=peer`	`tls-verify`	Server-certificate verification mode: `peer` (default) or `none`.

Notes:

Server-certificate verification is on by default. Provide a ca= (or capath=) so the server certificate can be validated. Use verify=none only for testing — it disables verification entirely.
When connecting by IP address, set sni= to the name present in the server certificate so hostname verification succeeds.
Client certificate (cert=) and key (clientkey=) must be supplied together for mutual TLS, or both omitted.
Set connect_timeout=<seconds> when using TLS so a misconfigured plaintext endpoint cannot block the TLS handshake indefinitely.
As with all connection-string keys, values may not contain spaces; keep certificate paths space-free.

Example (verify the server with a CA bundle):

--redis-userdb="host=redis.example.com port=6390 dbname=2 password=turn tls=true ca=/etc/coturn/redis-ca.crt connect_timeout=10"

Example with mutual TLS:

--redis-statsdb="host=redis.example.com port=6390 password=turn tls=true ca=/etc/coturn/redis-ca.crt cert=/etc/coturn/client.crt clientkey=/etc/coturn/client.key connect_timeout=10"

The same tls=* keys apply to both --redis-userdb and --redis-statsdb.

Redis can be also used for the TURN allocation status check and for status and traffic notifications.

See the explanation in the turndb/schema.stats.redis file, and an example in turndb/testredisdbsetup.sh file. One special thing about TURN Redis security setup is that you can store open passwords for long-term credentials in Redis. You cannot set open passwords for long-term credentials in SQLite or MySQL or PostgreSQL - with those DBs, you have to use the keys only. With Redis, you have a choice - keys or open passwords.

You also have to take care about Redis connection parameters, the timeout and the keepalive. The following settings must be in your Redis config file (/etc/redis.conf or /usr/local/etc/redis.conf):

.......... timeout 0 .......... tcp-keepalive 60 ..........

Redis TURN admin commands:

Shared secret for the TURN REST API (realm north.gov):

$ bin/turnadmin -s logen -r north.gov -N "host=localhost dbname=2 user=turn password=turn"

Long-term credentials mechanism:

$ bin/turnadmin -a -N "host=localhost dbname=2 user=turn password=turn" -u gorst -r north.gov -p hero $ bin/turnadmin -a -N "host=localhost dbname=2 user=turn password=turn" -u ninefingers -r north.gov -p youhavetoberealistic

Admin users:

$ bin/turnadmin -A -N "host=localhost dbname=2 user=turn password=turn" -u gorst -p hero $ bin/turnadmin -A -N "host=localhost dbname=2 user=turn password=turn" -u ninefingers -p youhavetoberealistic -r north.gov

See the file testredisdbsetup.sh for the data structure examples.