Setting up a masternode requires a basic understanding of Linux and blockchain technology, as well as an ability to follow instructions closely. It also requires regular maintenance and careful security, particularly if you are not storing your Umbru on a hardware wallet. There are some decisions to be made along the way, and optional extra steps to take for increased security.


  • 5000 Umbru

  • A Umbru wallet (Umbru Core or hardware wallet)

  • A Linux server, preferably a Virtual Private Server (VPS)

Setting up VPS

Login to your VPS and we will update the system from the Ubuntu package repository:

apt update
apt upgrade

The system will show a list of upgradable packages. Press Y and Enter to install the packages. We will now install a firewall (and some other packages we will use later), add swap memory and reboot the server to apply any necessary kernel updates, and then login to our newly secured environment as the new user:

apt install ufw python virtualenv git unzip pv

(press Y and Enter to confirm)

ufw allow ssh/tcp
ufw limit ssh/tcp
ufw allow 12353/tcp
ufw logging on
ufw enable

(press Y and Enter to confirm)

fallocate -l 4G /swapfile
chmod 600 /swapfile
mkswap /swapfile
swapon /swapfile
nano /etc/fstab

Add the following line at the end of the file (press tab to separate each word/number), then press Ctrl + X to close the editor, then Y and Enter save the file.

/swapfile none swap sw 0 0

Sending collateral

A Umbru address with a single unspent transaction output (UTXO) of exactly 5000 UMBRU is required to operate a masternode. Once it has been sent, various keys regarding the transaction must be extracted for later entry in a configuration file and registration transaction as proof to write the configuration to the blockchain so the masternode can be included in the deterministic list. A masternode can be registered from the official Umbru Core wallet.

Click Tools > Debug console to open the console. Type the following command into the console to generate a new Umbru address for the collateral:


Take note of the collateral address, since we will need it later. The next step is to secure your wallet (if you have not already done so). First, encrypt the wallet by selecting Settings > Encrypt wallet. You should use a strong, new password that you have never used somewhere else. Take note of your password and store it somewhere safe or you will be permanently locked out of your wallet and lose access to your funds. Next, back up your wallet file by selecting File > Backup Wallet. Save the file to a secure location physically separate to your computer, since this will be the only way you can access our funds if anything happens to your computer.

Now send exactly 5000 UMBRU in a single transaction to the new address you generated in the previous step. This may be sent from another wallet, or from funds already held in your current wallet. Once the transaction is complete, view the transaction in a blockchain explorer by searching for the address. You will need 15 confirmations before you can register the masternode, but you can continue with the next step at this point already: generating your masternode operator key.

Installing Umbru Core on VPS

Go to your VPS terminal window and enter the following command, to get the latest version of Umbru Core by right clicking or pressing Ctrl + V:


Create a working directory for Umbru, extract the compressed archive and copy the necessary files to the directory by using the following commands:

mkdir ~/.umbru
tar xfv umbrucore-
cp -f umbrud ~/.umbru/
cp -f umbru-cli ~/.umbru/

Create a configuration file using the following command:

nano ~/.umbru/umbru.conf

An editor window will appear. We now need to create a configuration file specifying several variables. Copy and paste the following text to get started, then replace the variables specific to your configuration as follows:


Replace the fields marked with XXXXXXX as follows:

  • rpcuser: enter any string of numbers or letters, no special characters allowed

  • rpcpassword: enter any string of numbers or letters, no special characters allowed

  • externalip: this is the IP address of your VPS

Leave the masternode and masternodeblsprivkey fields commented out for now.

Press Ctrl + X to close the editor and Y and Enter save the file. You can now start running Umbru on the masternode to begin synchronization with the blockchain:


You will see a message reading Umbru Core server starting. We will now install Sentinel, a piece of software which operates as a watchdog to communicate to the network that your node is working properly:

cd ~/.umbru
git clone
cd sentinel
virtualenv venv
venv/bin/pip install -r requirements.txt
venv/bin/python bin/

You will see a message reading umbrud not synced with network! Awaiting full sync before running Sentinel. Add umbrud and sentinel to crontab to make sure it runs every minute to check on your masternode:

crontab -e

Choose nano as your editor and enter the following lines at the end of the file:

* * * * * cd ~/.umbru/sentinel && ./venv/bin/python bin/ 2>&1 >> sentinel-cron.log
* * * * * pidof umbrud || ~/.umbru/umbrud

Press enter to make sure there is a blank line at the end of the file, then press Ctrl + X to close the editor and Y and Enter save the file. We now need to wait for 15 confirmations of the collateral transaction to complete, and wait for the blockchain to finish synchronizing on the masternode. You can use the following commands to monitor progress:

~/.umbru/umbru-cli mnsync status

When synchronization is complete, you should see the following response:

"AssetID": 999,
"AssetStartTime": 1566039979,
"Attempt": 0,
"IsBlockchainSynced": true,
"IsSynced": true,
"IsFailed": false

Continue with the next step to construct the ProTx transaction required to enable your masternode.

Registering Masternode

Identify the funding transaction

If you used an address in Umbru Core wallet for your collateral transaction, you now need to find the txid of the transaction. Click Tools > Debug console and enter the following command:

masternode outputs

This should return a string of characters similar to the following:

"16347a28f4e5edf39f4dceac60e2327931a25fdee1fb4b94b63eeacf0d5879e3" : "1",

The first long string is your collateralHash, while the last number is the collateralIndex.

Generate a BLS key pair

A public/private BLS key pair is required to operate a masternode. The private key is specified on the masternode itself, and allows it to be included in the deterministic masternode list once a provider registration transaction with the corresponding public key has been created.

If you are using a hosting service, they may provide you with their public key, and you can skip this step. If you are hosting your own masternode or have agreed to provide your host with the BLS private key, generate a BLS public/private keypair in Umbru Core by clicking Tools > Debug console and entering the following command:

bls generate
"secret": "6d7280762db6e7322ccce9bed2c9664d7fc186e9f21cf68ebb22f29cafd94eed",
"public": "93fc08a30a02880d2c85275d735c223fbb64c070b133bb214f69cbe5db70d3f90285bb47cd48d58c24796e1156d5aeaf"

These keys are NOT stored by the wallet and must be kept secure.

Add the private key to your masternode configuration

The public key will be used in following steps. The private key must be entered in the umbru.conf file on the masternode. This allows the masternode to watch the blockchain for relevant ProTx transactions, and will cause it to start serving as a masternode when the signed ProRegTx is broadcast by the owner (final step below). Log in to your masternode using ssh or PuTTY and edit the configuration file as follows:

nano ~/.umbru/umbru.conf

The editor appears with the existing masternode configuration. Add or uncomment these lines in the file, replacing the key with your BLS private key generated above:


Press enter to make sure there is a blank line at the end of the file, then press Ctrl + X to close the editor and Y and Enter save the file. We now need to restart the masternode for this change to take effect. Enter the following commands, waiting a few seconds in between to give Umbru Core time to shut down:

~/.umbru/umbru-cli stop
sleep 15

We will now prepare the transaction used to register the masternode on the network.

Prepare a ProRegTx transaction

A pair of BLS keys for the operator were already generated above, and the private key was entered on the masternode. The public key is used in this transaction as the operatorPubKey.

First, we need to get a new, unused address from the wallet to serve as the owner key address (ownerKeyAddr). This is not the same as the collateral address holding 5000 UMBRU. Generate a new address as follows:


This address can also be used as the voting key address (votingKeyAddr). Alternatively, you can specify an address provided to you by your chosen voting delegate, or simply generate a new voting key address as follows:


Then either generate or choose an existing address to receive the owner’s masternode payouts (payoutAddress). It is also possible to use an address external to the wallet:


You can also optionally generate and fund another address as the transaction fee source(feeSourceAddress). If you selected an external payout address, you must specify a fee source address. Either the payout address or fee source address must have enough balance to pay the transaction fee, or the final register_submit transaction will fail.

The private keys to the owner and fee source addresses must exist in the wallet submitting the transaction to the network. If your wallet is protected by a password, it must now be unlocked to perform the following commands. Unlock your wallet for 5 minutes:

walletpassphrase yourSecretPassword 300

We will now prepare an unsigned ProRegTx special transaction using the protx register_preparecommand. This command has the following syntax:

protx register_prepare collateralHash collateralIndex ipAndPort ownerKeyAddr
operatorPubKey votingKeyAddr operatorReward payoutAddress (feeSourceAddress)

Open a text editor such as notepad to prepare this command. Replace each argument to the command as follows:

  • collateralHash: The txid of the 5000 UMBRU collateral funding transaction

  • collateralIndex: The output index of the 5000 UMBRU funding transaction

  • ipAndPort: Masternode IP address and port, in the format x.x.x.x:yyyy

  • ownerKeyAddr: The new Umbru address generated above for the owner/voting address

  • operatorPubKey: The BLS public key generated above (or provided by your hosting service)

  • votingKeyAddr: The new Umbru address generated above, or the address of a delegate, used for proposal voting

  • operatorReward: The percentage of the block reward allocated to the operator as payment

  • payoutAddress: A new or existing Umbru address to receive the owner’s masternode rewards

  • feeSourceAddress: An (optional) address used to fund ProTx fee. payoutAddress will be used if not specified.

Note that the operator is responsible for specifying their own reward address in a separate update_service transaction if you specify a non-zero operatorReward. The owner of the masternode collateral does not specify the operator’s payout address.Example (remove line breaks if copying):

protx register_prepare


"tx": "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",
"collateralAddress": "UXvkAbdfwCXxGjaPDmAmw5uNqGHmEoFiNS",
"signMessage": "yjZVt49WsQd6XSrPVAUGXtJccxviH9ZQpN|0|yfgxFhqrdDG15ZWKJAN6dQvn6dZdgBPAip|yfRaZN8c3Erpqj9iKnmQ9QDBeUuRhWV3Mg|ad5f82257bd00a5a1cb5da1a44a6eb8899cf096d3748d68b8ea6d6b10046a28e"

Next we will use the collateralAddress and signMessage fields to sign the transaction, and the output of the tx field to submit the transaction.

Sign the ProRegTx transaction

We will now sign the content of the signMessage field using the private key for the collateral address as specified in collateralAddress. Note that no internet connection is required for this step, meaning that the wallet can remain disconnected from the internet in cold storage to sign the message. In this example we will again use Umbru Core, but it is equally possible to use the signing function of a hardware wallet. The command takes the following syntax:

signmessage collateralAddress signMessage


signmessage UXvkAbdfwCXxGjaPDmAmw5uNqGHmEoFiNS yjZVt49WsQd6XSrPVAUGXtJccxviH9ZQpN|0|yfgxFhqrdDG15ZWKJAN6dQvn6dZdgBPAip|yfRaZN8c3Erpqj9iKnmQ9QDBeUuRhWV3Mg|ad5f82257bd00a5a1cb5da1a44a6eb8899cf096d3748d68b8ea6d6b10046a28e



Submit the signed message

We will now submit the ProRegTx special transaction to the blockchain to register the masternode. This command must be sent from a Umbru Core wallet holding a balance on either the feeSourceAddress or payoutAddress, since a standard transaction fee is involved. The command takes the following syntax:

protx register_submit tx sig


  • tx: The serialized transaction previously returned in the tx output field from the protx register_prepare command

  • sig: The message signed with the collateral key from the signmessage command


protx register_submit 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 II8JvEBMj6I3Ws8wqxh0bXVds6Ny+7h5HAQhqmd5r/0lWBCpsxMJHJT3KBcZ23oUZtsa6gjgISf+a8GzJg1BfEg=



Your masternode is now registered and will appear on the Deterministic Masternode List after the transaction is mined to a block. You can view this list on the Masternodes -> Umbru Masternodes tab of the Umbru Core wallet, or in the console using the command protx list valid, where the txid of the final protx register_submit transaction identifies your masternode.