Expanding on Hudson Jameson's answer: "The hexadecimal node ID is encoded in the username portion of the URL"

The username portion is a 512-bit public key that is used to verify communication came from a particular node on the network.

More about the RLPx protocol used can be found here: https://github.com/ethereum/devp2p/blob/master/rlpx.md#network-formation

Main parts of that:

Node discovery and network formation are implemented via a kademlia-like UDP. Major differences from Kademlia:

• packets are signed
• node ids are public keys
• DHT-related features are excluded. FIND_VALUE and STORE packets are not implemented.
• xor distance metric is based on sha3(nodeid)

Expanding on Hudson Jameson's answer: "The hexadecimal node ID is encoded in the username portion of the URL"

The username portion is a 512-bit public key that is used to verify communication came from a particular node on the network.

More about the RLPx protocol used can be found here.

Main parts of that:

Node discovery and network formation are implemented via a kademlia-like UDP. Major differences from Kademlia:

• packets are signed
• node ids are public keys
• DHT-related features are excluded. FIND_VALUE and STORE packets are not implemented.
• xor distance metric is based on sha3(nodeid)