The version message is a part of the node connection handshake and indicates various connection settings, networking information, and the services provided by the sending node (see Services Bitmask below).
The node connection is not considered established until both nodes have sent and received both a <code>version</code> and [verack](/protocol/network/messages/verack) message.
| version | 4 bytes | unsigned integer<sup>[(LE)](/protocol/misc/endian/little)</sup> | The version number supported by the sending node. |
| services | 8 bytes | bitmask<sup>[(LE)](/protocol/misc/endian/little)</sup> | An indication of the services supported by the sending node. See Services Bitmask section below. |
| timestamp | 8 bytes | unix timestamp<sup>[(LE)](/protocol/misc/endian/little)</sup> | The time the message was generated on the sending node. |
| remote address | 26 bytes | [network address](/protocol/formats/network-address) | The network address of the remote node. <p>_NOTE: this does not contain the timestamp normally included with network addresses._</p> |
| local address | 26 bytes | [network address](/protocol/formats/network-address) | The network address of the sending node. <p>_NOTE: this does not contain the timestamp normally included with network addresses._</p> |
| nonce | 8 bytes | bytes<sup>[(LE)](/protocol/misc/endian/little)</sup> | Random nonce for the connection, used to detect connections to self. |
| user agent | variable | [variable length string](/protocol/formats/variable-length-string) | A user agent string identifying the node implementation. |
| block height | 4 bytes | unsigned integer<sup>[(LE)](/protocol/misc/endian/little)</sup> | The height of the block with the highest height known to the sending node. |
| relay flag | 1 byte | boolean | Indicates whether the sending node would like all broadcasted transactions relayed to it. See [BIP-37](https://github.com/bitcoin/bips/blob/master/bip-0037.mediawiki). |
The services field is an 8 byte little-endian-serialized bitfield that described peer capabilities. The following capabilities are defined, by bit position:
### Standard Services
* 0: NODE_NETWORK
The node is capable of serving the complete block chain. It is currently set by all full nodes, and is unset by SPV clients or other peers that just want network services but don't provide them.
* 2: NODE_BLOOM
The node is capable and willing to handle bloom-filtered connections.
* 3: NODE_WITNESS
Indicates that a node can be asked for blocks and transactions including witness data.
*Bitcoin Cash nodes do not have witness data so this flag should be ignored on receipt and set to 0 when sent*
* 5: NODE_BITCOIN_CASH
The node supports the BCH chain. This is intended to be just a temporary service bit until the BTC/BCH fork actually happens.
These bits are reserved for temporary experiments. Just pick a bit that isn't getting used, or one not being used much, and notify the community. Remember that service bits are just unauthenticated advertisements, so your code must be robust against collisions and other cases where nodes may be advertising a service they do not actually support.
This means the same as NODE_NETWORK with the limitation of only serving a small subset of the blockchain. See [BIP159](https://github.com/bitcoin/bips/blob/master/bip-0159.mediawiki) for details on how this is implemented.
This means the same as NODE_NETWORK with the limitation of only serving a small subset of the blockchain. See [BIP159](https://github.com/bitcoin/bips/blob/master/bip-0159.mediawiki) for details on how this is implemented.
The node is capable of responding to the getutxo protocol request. See [BIP 64](https://github.com/bitcoin/bips/blob/master/bip-0064.mediawiki) for details on how this is implemented. _Was previously supported by Bitcoin XT only._
Indicates the node is capable of serving compact block filters to SPV clients, AKA the "Neutrino" protocol ([BIP157](https://github.com/bitcoin/bips/blob/master/bip-0157.mediawiki), and [BIP158](https://github.com/bitcoin/bips/blob/master/bip-0158.mediawiki)).
Generally, though node implementations may be aware of services they do not provide, they generally ignore those they don't supported. Any notable deviations from that behavior are documented below.
### Bitcoin ABC
Bitcoin ABC nodes may, once they have reached their maximum number of peers, selectively disconnect from nodes that do not supported "desired services", though it appears currently this just <code>NODE_NETWORK</code> and/or <code>NODE_NETWORK_LIMITED</code>. That is, it may prefer nodes that store and serve blocks.
