This guide describes how to add Solana's native token SOL to your cryptocurrency exchange.
We highly recommend setting up at least two nodes on high-grade computers/cloud instances, upgrading to newer versions promptly, and keeping an eye on service operations with a bundled monitoring tool.
This setup enables you:
- to have a trusted gateway to the Solana mainnet-beta cluster to get data and submit withdrawal transactions
- to have full control over how much historical block data is retained
- to maintain your service availability even if one node fails
Solana nodes demand relatively high computing power to handle our fast blocks and high TPS. For specific requirements, please see hardware recommendations.
To run an api node:
- Install the Solana command-line tool suite
- Start the validator with at least the following parameters:
--ledger to your desired ledger storage location, and
--rpc-port to the port you want to expose.
--expected-genesis-hash parameters are all specific to the cluster you are joining.
Current parameters for Mainnet Beta
--limit-ledger-size parameter allows you to specify how many ledger
shreds your node retains on disk. If you do not
include this parameter, the validator will keep the entire ledger until it runs
out of disk space. The default value attempts to keep the ledger disk usage
under 500GB. More or less disk usage may be requested by adding an argument to
--limit-ledger-size if desired. Check
solana-validator --help for the
default limit value used by
--limit-ledger-size. More information about
selecting a custom limit value is available
Specifying one or more
--trusted-validator parameters can protect you from booting from a malicious snapshot. More on the value of booting with trusted validators
Optional parameters to consider:
--private-rpcprevents your RPC port from being published for use by other nodes
--rpc-bind-addressallows you to specify a different IP address to bind the RPC port
Automatic Restarts and Monitoring
We recommend configuring each of your nodes to restart automatically on exit, to ensure you miss as little data as possible. Running the solana software as a systemd service is one great option.
For monitoring, we provide
which can monitor your validator and detect with the
is unhealthy. It can directly be configured to alert you via Slack, Telegram,
Discord, or Twillio. For details, run
New Software Release Announcements
We release new software frequently (around 1 release / week). Sometimes newer versions include incompatible protocol changes, which necessitate timely software update to avoid errors in processing blocks.
Our official release announcements for all kinds of releases (normal and
security) are communicated via a discord channel called
mb stands for
Like staked validators, we expect any exchange-operated validators to be updated at your earliest convenience within a business day or two after a normal release announcement. For security-related releases, more urgent action may be needed.
By default, each of your nodes will boot from a snapshot provided by one of your
trusted validators. This snapshot reflects the current state of the chain, but
does not contain the complete historical ledger. If one of your node exits and
boots from a new snapshot, there may be a gap in the ledger on that node. In
order to prevent this issue, add the
--no-snapshot-fetch parameter to your
solana-validator command to receive historical ledger data instead of a
Do not pass the
--no-snapshot-fetch parameter on your initial boot as it's not
possible to boot the node all the way from the genesis block. Instead boot from
a snapshot first and then add the
--no-snapshot-fetch parameter for reboots.
It is important to note that the amount of historical ledger available to your nodes from the rest of the network is limited at any point in time. Once operational if your validators experience significant downtime they may not be able to catch up to the network and will need to download a new snapshot from a trusted validator. In doing so your validators will now have a gap in its historical ledger data that cannot be filled.
Minimizing Validator Port Exposure
The validator requires that various UDP and TCP ports be open for inbound traffic from all other Solana validators. While this is the most efficient mode of operation, and is strongly recommended, it is possible to restrict the validator to only require inbound traffic from one other Solana validator.
First add the
--restricted-repair-only-mode argument. This will cause the
validator to operate in a restricted mode where it will not receive pushes from
the rest of the validators, and instead will need to continually poll other
validators for blocks. The validator will only transmit UDP packets to other
validators using the Gossip and ServeR ("serve repair") ports, and only
receive UDP packets on its Gossip and Repair ports.
The Gossip port is bi-directional and allows your validator to remain in contact with the rest of the cluster. Your validator transmits on the ServeR to make repair requests to obtaining new blocks from the rest of the network, since Turbine is now disabled. Your validator will then receive repair responses on the Repair port from other validators.
To further restrict the validator to only requesting blocks from one or more
validators, first determine the identity pubkey for that validator and add the
--gossip-pull-validator PUBKEY --repair-validator PUBKEY arguments for each
PUBKEY. This will cause your validator to be a resource drain on each validator
that you add, so please do this sparingly and only after consulting with the
Your validator should now only be communicating with the explicitly listed validators and only on the Gossip, Repair and ServeR ports.
Setting up Deposit Accounts
Solana accounts do not require any on-chain initialization; once they contain some SOL, they exist. To set up a deposit account for your exchange, simply generate a Solana keypair using any of our wallet tools.
We recommend using a unique deposit account for each of your users.
Solana accounts are charged rent on creation and once per
epoch, but they can be made rent-exempt if they contain 2-years worth of rent in
SOL. In order to find the minimum rent-exempt balance for your deposit accounts,
You may wish to keep the keys for one or more collection accounts offline for greater security. If so, you will need to move SOL to hot accounts using our offline methods.
Listening for Deposits
When a user wants to deposit SOL into your exchange, instruct them to send a transfer to the appropriate deposit address.
Poll for Blocks
To track all the deposit accounts for your exchange, poll for each confirmed block and inspect for addresses of interest, using the JSON-RPC service of your Solana API node.
- To identify which blocks are available, send a
getConfirmedBlocksrequest, passing the last block you have already processed as the start-slot parameter:
Not every slot produces a block, so there may be gaps in the sequence of integers.
- For each block, request its contents with a
postBalances fields allow you to track the balance
changes in every account without having to parse the entire transaction. They
list the starting and ending balances of each account in
lamports, indexed to the
accountKeys list. For
example, if the deposit address if interest is
47Sbuv6jL7CViK9F2NMW51aQGhfdpUu7WNvKyH645Rfi, this transaction represents a
transfer of 218099990000 - 207099990000 = 11000000000 lamports = 11 SOL
You can also query the transaction history of a specific address. This is generally not a viable method for tracking all your deposit addresses over all slots, but may be useful for examining a few accounts for a specific period of time.
- Send a
getConfirmedSignaturesForAddress2request to the api node:
- For each signature returned, get the transaction details by sending a
To accommodate a user's request to withdraw SOL, you must generate a Solana transfer transaction, and send it to the api node to be forwarded to your cluster.
Sending a synchronous transfer to the Solana cluster allows you to easily ensure that a transfer is successful and finalized by the cluster.
Solana's command-line tool offers a simple command,
solana transfer, to
generate, submit, and confirm transfer transactions. By default, this method
will wait and track progress on stderr until the transaction has been finalized
by the cluster. If the transaction fails, it will report any transaction errors.
offers a similar approach for the JS ecosystem. Use the
SystemProgram to build
a transfer transaction, and submit it using the
For greater flexibility, you can submit withdrawal transfers asynchronously. In these cases, it is your responsibility to verify that the transaction succeeded and was finalized by the cluster.
Note: Each transaction contains a recent blockhash to indicate its liveness. It is critical to wait until this blockhash expires before retrying a withdrawal transfer that does not appear to have been confirmed or finalized by the cluster. Otherwise, you risk a double spend. See more on blockhash expiration below.
First, get a recent blockhash using the
or the CLI command:
In the command-line tool, pass the
--no-wait argument to send a transfer
asynchronously, and include your recent blockhash with the
You can also build, sign, and serialize the transaction manually, and fire it off to
the cluster using the JSON-RPC
Transaction Confirmations & Finality
Get the status of a batch of transactions using the
getSignatureStatuses JSON-RPC endpoint.
confirmations field reports how many
confirmed blocks have elapsed since the
transaction was processed. If
confirmations: null, it is finalized.
You can check whether a particular blockhash is still valid by sending a
request with the blockhash as a parameter. If the response value is
blockhash is expired, and the withdrawal transaction using that blockhash should
Validating User-supplied Account Addresses for Withdrawals
As withdrawals are irreversible, it may be a good practice to validate a user-supplied account address before authorizing a withdrawal in order to prevent accidental loss of user funds.
The address of a normal account in Solana is a Base58-encoded string of a 256-bit ed25519 public key. Not all bit patterns are valid public keys for the ed25519 curve, so it is possible to ensure user-supplied account addresses are at least correct ed25519 public keys.
Here is a Java example of validating a user-supplied address as a valid ed25519 public key:
The following code sample assumes you're using the Maven.
Supporting the SPL Token Standard
SPL Token is the standard for wrapped/synthetic token creation and exchange on the Solana blockchain.
The SPL Token workflow is similar to that of native SOL tokens, but there are a few differences which will be discussed in this section.
Each type of SPL Token is declared by creating a mint account. This account stores metadata describing token features like the supply, number of decimals, and various authorities with control over the mint. Each SPL Token account references its associated mint and may only interact with SPL Tokens of that type.
spl-token CLI Tool
SPL Token accounts are queried and modified using the
spl-token command line
utility. The examples provided in this section depend upon having it installed
on the local system.
spl-token is distributed from Rust crates.io
via the Rust
cargo command line utility. The latest version of
cargo can be
installed using a handy one-liner for your platform at rustup.rs.
cargo is installed,
spl-token can be obtained with the following command:
You can then check the installed version to verify
Which should result in something like
SPL Token accounts carry additional requirements that native System Program accounts do not:
- SPL Token accounts must be created before an amount of tokens can be
deposited. Token accounts can be created explicitly with the
spl-token create-accountcommand, or implicitly by the
spl-token transfer --fund-recipient ...command.
- SPL Token accounts must remain rent-exempt for the duration of their existence and therefore require a small amount of native SOL tokens be deposited at account creation. For SPL Token v2 accounts, this amount is 0.00203928 SOL (2,039,280 lamports).
To create an SPL Token account with the following properties:
- Associated with the given mint
- Owned by the funding account's keypair
Or to create an SPL Token account with a specific keypair:
Checking an Account's Balance
The source account for a transfer is the actual token account that contains the amount.
The recipient address however can be a normal wallet account. If an associated
token account for the given mint does not yet exist for that wallet, the
transfer will create it provided that the
--fund-recipient argument as
(user, mint) pair requires a separate account on chain, it is
recommended that an exchange create batches of token accounts in advance and assign them
to users on request. These accounts should all be owned by exchange-controlled
Monitoring for deposit transactions should follow the block polling method described above. Each new block should be scanned for successful transactions issuing SPL Token Transfer or Transfer2 instructions referencing user accounts, then querying the token account balance updates.
Considerations are being
made to exend the
postBalance transaction status metadata
fields to include SPL Token balance transfers.
The withdrawal address a user provides should be the same address used for regular SOL withdrawal.
From the withdrawal address, the associated token account for the correct mint determined and the transfer issued to that account. Note that it's possible that the associated token account does not yet exist, at which point the exchange should fund the account on behalf of the user. For SPL Token v2 accounts, funding the withdrawal account will require 0.00203928 SOL (2,039,280 lamports).
spl-token transfer command for a withdrawal:
For regulatory compliance reasons, an SPL Token issuing entity may optionally choose to hold "Freeze Authority" over all accounts created in association with its mint. This allows them to freeze the assets in a given account at will, rendering the account unusable until thawed. If this feature is in use, the freeze authority's pubkey will be registered in the SPL Token's mint account.
Testing the Integration
Be sure to test your complete workflow on Solana devnet and testnet
clusters before moving to production on mainnet-beta. Devnet
is the most open and flexible, and ideal for initial development, while testnet
offers more realistic cluster configuration. Both devnet and testnet support a faucet,
solana airdrop 1 to obtain some devnet or testnet SOL for developement and testing.