Discovery
94 |After a user has generated their identity they need to find some 95 | peers to connect to. To connect to a peer you need its public key and 96 | its address using any of the protocol it supports. Typically with 97 | TCP/IP, you would need its IP address and port, but the Scuttlebutt 98 | protocol is not restricted to TCP/IP as transport. The Scuttlebutt 99 | protocol currently has three methods for peers to discover each 100 | other.
101 |Local network
102 |Peers constantly broadcast UDP packets on their local network
103 | advertising their presence. The body of each packet is a string
104 | containing the peer’s IP address, port and base64-encoded public key
105 | (without @ or .ed25519):
107 |122 |109 |
108 | Implementations
JS:
110 |111 |
116 |- broadcast-stream
113 |- ssb-local
115 |Java:
117 |118 |
121 |- LocalDiscoveryService
120 |
| Source IP | 126 |Source port | 127 |Destination IP | 128 |Destination port | 129 |
|---|---|---|---|
| 192.168.1.123 | 134 |8008 | 135 |255.255.255.255 | 136 |8008 | 137 |
143 |
145 | This message format can be any valid multiserver
148 | address. In local networks, this is usually a net
149 | address with an IPv4 or IPv6 address.
Current implementations broadcast one of these packets every second. 151 | When a peer sees another peer’s broadcast packet they can connect to 152 | exchange messages. Some clients show nearby peers in the user interface 153 | so that the user can see other people on the same network as them.
154 |UDP source and destination ports are set to the same port number that 155 | the peer is listening on TCP for peer connections (normally 8008).
156 |Invite code
157 |Invite codes help new users get connected to 158 | their first pub, which is a Scuttlebutt peer that is 159 | publicly accessible over the internet. An invite code contains a pub’s 160 | domain name, port and public key.
161 |They also contain a secret key that the user can redeem to make the pub follow them back. This lets the new user see 164 | messages posted by other members of the pub and share their own 165 | messages. Invite codes are the most common way for new users to get 166 | started on Scuttlebutt.
167 |Pub operators can distribute invite codes any way they see fit, for 168 | example by posting them on existing social networks. Some pubs have a 169 | web page that anybody can visit to generate an invite code.
170 |Pub message
171 |Users can post a message to their own feed 172 | advertising a pub:
173 |Here the user @FCX/ts… is advertising that they know of
174 | pub @VJM7w1… along with the pub’s domain name and port.
{
176 | "author": "@FCX/tsDLpubCPKKfIrw4gc+SQkHcaD17s7GI6i/ziWY=.ed25519",
177 | "content": {
178 | "type": "pub",
179 | "address": {
180 | "host": "one.butt.nz",
181 | "port": 8008,
182 | "key": "@VJM7w1W19ZsKmG2KnfaoKIM66BRoreEkzaVm/J//wl8=.ed25519"
183 | }
184 | },
185 | …
186 | }When others see this message they can make a note that this pub 188 | exists and connect to it in the future.
189 |Pub messages are a useful way to find additional peers if you already 190 | know a few. Obviously this doesn’t work for new users who don’t know 191 | anyone else yet and therefore can’t see any pub messages.
192 |
105 | 
121 |