# Command line options

You can pass any `nimbus_beacon_node` options to the `prater` and `mainnet` scripts. For example, if you want to launch Nimbus on mainnet with different base ports than the default `9000/udp` and `9000/tcp`, say `9100/udp` and `9100/tcp`, run:

```
./run-mainnet-beacon-node.sh --tcp-port=9100 --udp-port=9100
```

To see a list of the command line options availabe to you, with descriptions, run:

```
build/./nimbus_beacon_node --help
```

You should see the following output:

```
Usage:

nimbus_beacon_node [OPTIONS]... command

The following options are available:

     --log-level               Sets the log level for process and topics (e.g. "DEBUG; TRACE:discv5,libp2p;
                               REQUIRED:none; DISABLED:none") [=INFO].
     --log-file                Specifies a path for the written Json log file (deprecated).
     --network                 The Eth2 network to join [=mainnet].
 -d, --data-dir                The directory where nimbus will store all blockchain data.
     --validators-dir          A directory containing validator keystores.
     --secrets-dir             A directory containing validator keystore passwords.
     --wallets-dir             A directory containing wallet files.
     --web3-url                One or more Web3 provider URLs used for obtaining deposit contract data.
     --non-interactive         Do not display interative prompts. Quit on missing configuration.
     --netkey-file             Source of network (secp256k1) private key file (random|<path>) [=random].
     --insecure-netkey-password  Use pre-generated INSECURE password for network private key file [=false].
     --agent-string            Node agent string which is used as identifier in network [=nimbus].
     --subscribe-all-subnets   Subscribe to all attestation subnet topics when gossiping [=false].
     --num-threads             Number of worker threads (set this to 0 to use as many threads as there are CPU
                               cores available) [=1].
 -b, --bootstrap-node          Specifies one or more bootstrap nodes to use when connecting to the network.
     --bootstrap-file          Specifies a line-delimited file of bootstrap Ethereum network addresses.
     --listen-address          Listening address for the Ethereum LibP2P and Discovery v5 traffic [=0.0.0.0].
     --tcp-port                Listening TCP port for Ethereum LibP2P traffic [=9000].
     --udp-port                Listening UDP port for node discovery [=9000].
     --max-peers               The maximum number of peers to connect to [=160].
     --nat                     Specify method to use for determining public address. Must be one of: any, none,
                               upnp, pmp, extip:<IP> [=any].
     --enr-auto-update         Discovery can automatically update its ENR with the IP address and UDP port as
                               seen by other nodes it communicates with. This option allows to enable/disable
                               this functionality [=false].
     --weak-subjectivity-checkpoint  Weak subjectivity checkpoint in the format block_root:epoch_number.
     --node-name               A name for this node that will appear in the logs. If you set this to 'auto', a
                               persistent automatically generated ID will be selected for each --data-dir
                               folder.
     --graffiti                The graffiti value that will appear in proposed blocks. You can use a
                               0x-prefixed hex encoded string to specify raw bytes.
     --verify-finalization     Specify whether to verify finalization occurs on schedule, for testing [=false].
     --stop-at-epoch           A positive epoch selects the epoch at which to stop [=0].
     --metrics                 Enable the metrics server [=false].
     --metrics-address         Listening address of the metrics server [=127.0.0.1].
     --metrics-port            Listening HTTP port of the metrics server [=8008].
     --status-bar              Display a status bar at the bottom of the terminal screen [=true].
     --status-bar-contents     Textual template for the contents of the status bar.
     --rpc                     Enable the JSON-RPC server [=false].
     --rpc-port                HTTP port for the JSON-RPC service [=9190].
     --rpc-address             Listening address of the RPC server [=127.0.0.1].
     --rest                    Enable the REST server [=false].
     --rest-port               Port for the REST server [=5052].
     --rest-address            Listening address of the REST server [=127.0.0.1].
     --rest-statecache-size    The maximum number of recently accessed states that are kept in memory. Speeds
                               up requests obtaining information for consecutive slots or epochs. [=3].
     --rest-statecache-ttl     The number of seconds to keep recently accessed states in memory [=60].
     --keymanager              Enable the REST keymanager API (BETA version) [=false].
     --keymanager-port         Listening port for the REST keymanager API [=5052].
     --keymanager-address      Listening port for the REST keymanager API [=127.0.0.1].
     --keymanager-token-file   A file specifying the authorizition token required for accessing the keymanager
                               API.
     --in-process-validators   Disable the push model (the beacon node tells a signing process with the private
                               keys of the validators what to sign and when) and load the validators in the
                               beacon node itself [=true].
     --discv5                  Enable Discovery v5 [=true].
     --dump                    Write SSZ dumps of blocks, attestations and states to data dir [=false].
     --direct-peer             The list of priviledged, secure and known peers to connect and maintain the
                               connection to, this requires a not random netkey-file. In the complete
                               multiaddress format like: /ip4/<address>/tcp/<port>/p2p/<peerId-public-key>.
                               Peering agreements are established out of band and must be reciprocal..
     --doppelganger-detection  If enabled, the beacon node prudently listens for 2 epochs for attestations from
                               a validator with the same index (a doppelganger), before sending an attestation
                               itself. This protects against slashing (due to double-voting) but means you will
                               miss two attestations when restarting. [=true].
     --validator-monitor-auto  Automatically monitor locally active validators (BETA) [=false].
     --validator-monitor-pubkey  One or more validators to monitor - works best when --subscribe-all-subnets is
                               enabled (BETA).
     --validator-monitor-totals  Publish metrics to single 'totals' label for better collection performance when
                               monitoring many validators (BETA) [=false].

...
```