Flags

The NATS server has many flags to customize its behavior without having to write a configuration file.

The configuration flags revolve around:

• Server Options

• Logging

• Authorization

• TLS Security

• Clustering

• Information

Server Options

Flag	Description
-a, --addr	Host address to bind to (default: 0.0.0.0 - all interfaces).
-p, --port	NATS client port (default: 4222).
-P, --pid	File to store the process ID (PID).
-m, --http_port	HTTP port for monitoring dashboard (exclusive of --https_port).
-ms, --https_port	HTTPS port monitoring for monitoring dashboard (exclusive of --http_port).
-c, --config	Path to NATS server configuration file.
-sl, --signal	Send a signal to nats-server process. See process signaling.
--client_advertise	Client HostPort to advertise to other servers.
-t	Test configuration and exit

Authentication Options

The following options control straightforward authentication:

Flag	Description
--user	Required username for connections (exclusive of --token).
--pass	Required password for connections (exclusive of --token).
--auth	Required authorization token for connections (exclusive of --user and --password).

See token authentication, and username/password for more information.

Logging Options

The following flags are available on the server to configure logging:

Flag	Description
-l, --log	File to redirect log output
-T, --logtime	Specify -T=false to disable timestamping log entries
-s, --syslog	Log to syslog or windows event log
-r, --remote_syslog	The syslog server address, like udp://localhost:514
-D, --debug	Enable debugging output
-V, --trace	Enable protocol trace log messages
-VV	Verbose trace (traces system account as well)
-DV	Enable both debug and protocol trace messages
-DVV	Debug and verbose trace (traces system account as well)
--max_traced_msg_len	Maximum printable length for traced messages. 0 for unlimited

You can read more about logging configuration here.

TLS Options

Flag	Description
--tls	Enable TLS, do not verify clients
--tlscert	Server certificate file
--tlskey	Private key for server certificate
--tlsverify	Enable client TLS certificate verification
--tlscacert	Client certificate CA for verification

You can read more about tls configuration here.

Cluster Options

The following flags are available on the server to configure clustering:

Flag	Description
--routes	Comma-separated list of cluster URLs to solicit and connect
--cluster	Cluster URL for clustering requests
--no_advertise	Do not advertise known cluster information to clients
--cluster_advertise	Cluster URL to advertise to other servers
--connect_retries	For implicit routes, number of connect retries

You can read more about clustering configuration here.

Common Options

Flag	Description
-h, --help	Show this message
-v, --version	Show version
--help_tls	TLS help