```{eval-rst} .. meta:: :title: Masternode Messages :description: The following network messages enable the masternode features built in to Dash. ``` # Masternode Messages The following network messages enable the [masternode](../resources/glossary.md#masternode) features built in to Dash. ![Overview Of P2P Protocol Masternode Request And Reply Messages](../../img/dev/en-p2p-masternode-messages.svg) For additional details, refer to the Developer Guide [Masternode Sync](../guide/dash-features-masternode-sync.md) and [Masternode Payment](../guide/dash-features-masternode-payment.md) sections. ## ssc The [`ssc` message](../reference/p2p-network-masternode-messages.md#ssc) is used to track the sync status of masternode objects. This message is sent in response to sync requests for the list of governance objects (`govsync` message), and governance object votes (`govsync` message). | Bytes | Name | Data type | Required | Description | | ---------- | ----------- | --------- | -------- | -------- | | 4 | nItemID | int | Required | Masternode Sync Item ID | 4 | nCount | int | Required | Number of items to sync Sync Item IDs | ID | Description | Response To |------|--------------|--------------- | 10 | MASTERNODE_SYNC_GOVOBJ | [`govsync` message](../reference/p2p-network-governance-messages.md#govsync) | 11 | MASTERNODE_SYNC_GOVOBJ_VOTE | [`govsync` message](../reference/p2p-network-governance-messages.md#govsync) with non-zero hash The following annotated hexdump shows a [`ssc` message](../reference/p2p-network-masternode-messages.md#ssc). (The message header has been omitted.) ``` text 02000000 ................................... Item ID: MASTERNODE_SYNC_LIST (2) bf110000 ................................... Count: 4543 ``` ## mnauth *Added in protocol version 70214* The [`mnauth` message](../reference/p2p-network-masternode-messages.md#mnauth) is sent by a [masternode](../resources/glossary.md#masternode) immediately after sending a [`verack` message](../reference/p2p-network-control-messages.md#verack) to authenticate that the sender is a masternode. It is only sent when the sender is actually a masternode. The [`mnauth` message](../reference/p2p-network-masternode-messages.md#mnauth) signs a challenge that was previously sent via a [`version` message](../reference/p2p-network-control-messages.md#version). The challenge is signed differently depending on if the connection is inbound or outbound. :::{note} As of protocol version 70218, when communicating with masternodes that have reported a version => `MIN_MASTERNODE_PROTO_VERSION`, the mnauth signature is created by signing a message incorporating both the `mnauth_challenge` and protocol `version` (from the [`version` message](../reference/p2p-network-control-messages.md#version)). Further details may be found in [Dash Core PR 3631](https://github.com/dashpay/dash/pull/3631). ::: This is primarily used as a DoS protection mechanism to allow persistent connections between masternodes to remain open even if inbound connection limits are reached. | Bytes | Name | Data type | Description | | --- | --- | --- | --- | | 32 | proRegTxHash | uint256 | The hash of the ProRegTx that identifies the masternode | 96 | sig | byte[] | BLS signature of the [`version` message's](../reference/p2p-network-control-messages.md#version) `mnauth_challenge`. Signed with the operator key of the masternode.
**Note**: serialized using the basic BLS scheme after Dash 19.0 activation The following annotated hexdump shows a [`mnauth` message](../reference/p2p-network-masternode-messages.md#mnauth). (The message header has been omitted.) ``` text 63cd3bf06404d78f80163afeb4b13e18 7dc1c1d04997ef04f1a2ecb3166dd004 ........... ProRegTx Hash 12f2706bc75e9cb14a9ebf1d93d177d5 f266ad2eddc49ad463810cb976a3e4bb abffc96819c5030fd5a7601af9c8ee50 0feb066b38a48af1a31b7242bd814bab 91e2a887f963904f33af851ddc9167d5 66d6d3bd6c07e99091edd8867d0dd56e ........... Masternode BLS Signature (96 bytes) ```