# OpenTTD's admin network Last updated: 2024-03-26 ## Table of contents - 1.0) [Preface](#10-preface) - 2.0) [Joining the network](#20-joining-the-network) - 3.0) [Asking for updates](#30-asking-for-updates) - 3.1) [Polling manually](#31-polling-manually) - 4.0) [Sending rcon commands](#40-sending-rcon-commands) - 5.0) [Sending chat](#50-sending-chat) - 5.1) [Receiving chat](#51-receiving-chat) - 6.0) [Disconnecting](#60-disconnecting) - 7.0) [Certain packet information](#70-certain-packet-information) ## 1.0) Preface The admin network provides a dedicated network protocol designed for other applications to communicate with OpenTTD. Connected applications can execute console commands remotely (rcon commands) with no further authentication. Furthermore information about clients and companies can be provided. Admin applications remain connected when starting a new game or loading a saved game in contrast to normal OpenTTD clients that get disconnected. This document describes the admin network and its protocol. Please refer to the mentioned enums in `src/network/core/tcp_admin.h` Please also note that further improvements to the admin protocol can mean that more packet types will be sent by the server. For forward compatibility it is therefore wise to ignore unknown packets. Future improvements might also add additional data to packets. This data should be ignored. Data will never be removed from packets in later versions, except the possibility that complete packets are dropped in favour of a new packet. This though will be reflected in the protocol version as announced in the `ADMIN_PACKET_SERVER_PROTOCOL` in section 2.0). A reference implementation in Java for a client connecting to the admin interface can be found at: [http://dev.openttdcoop.org/projects/joan](http://dev.openttdcoop.org/projects/joan) ## 2.0) Joining the network Create a TCP connection to the server on port 3977. The application is expected to authenticate within 10 seconds. To authenticate send either an `ADMIN_PACKET_ADMIN_JOIN` or an `ADMIN_PACKET_ADMIN_JOIN_SECURE` packet. The `ADMIN_PACKET_ADMIN_JOIN` packet sends the password without any encryption or safeguards over the connection, and as such has been disabled by default. The `ADMIN_PACKET_ADMIN_JOIN_SECURE` packet initiates a key exchange authentication schema which tells te server which methods the client supports and the server makes a choice. The server will then send an `ADMIN_PACKET_SERVER_AUTH_REQUEST` packet to which the client has to respond with an `ADMIN_PACKET_ADMIN_AUTH_RESPONSE` packet. The current choices for secure authentication are authorized keys, where the client has a private key and the server a list of authorized public keys, and a so-called password-authenticated key exchange which allows to authenticate using a password without actually sending the password. The server falls back to password authentication when the client's key is not in the list of authorized keys. When authentication has succeeded for either of the `JOIN` schemas, the server will reply with `ADMIN_PACKET_SERVER_PROTOCOL` followed directly by `ADMIN_PACKET_SERVER_WELCOME`. `ADMIN_PACKET_SERVER_PROTOCOL` contains details about the protocol version. It is the job of your application to check this number and decide whether it will remain connected or not. Furthermore, this packet holds details on every `AdminUpdateType` and the supported `AdminFrequencyTypes` (bitwise representation). `ADMIN_PACKET_SERVER_WELCOME` contains details on the server and the map, e.g. if the server is dedicated, its NetworkLanguage, size of the Map, etc. Once you have received `ADMIN_PACKET_SERVER_WELCOME` you are connected and authorized to do your thing. The server will not provide any game related updates unless you ask for them. There are four packets the server will none the less send, if applicable: - ADMIN_PACKET_SERVER_ERROR - ADMIN_PACKET_SERVER_WELCOME - ADMIN_PACKET_SERVER_NEWGAME - ADMIN_PACKET_SERVER_SHUTDOWN However, `ADMIN_PACKET_SERVER_WELCOME` only after a `ADMIN_PACKET_SERVER_NEWGAME` ## 3.0) Asking for updates Asking for updates is done with `ADMIN_PACKET_ADMIN_UPDATE_FREQUENCY`. With this packet you define which update you wish to receive at which frequency. Note: not every update type supports every frequency. If in doubt, you can verify against the data received in `ADMIN_PACKET_SERVER_PROTOCOL`. Please note the potential gotcha in the "Certain packet information" section below when using the `ADMIN_UPDATE_FREQUENCY` packet. The server will not confirm your registered update. However, asking for an invalid `AdminUpdateType` or a not supported `AdminUpdateFrequency` you will be disconnected from the server with `NETWORK_ERROR_ILLEGAL_PACKET`. Additional debug information can be found with a debug level of `net=3`. `ADMIN_UPDATE_DATE` results in the server sending: - ADMIN_PACKET_SERVER_DATE `ADMIN_UPDATE_CLIENT_INFO` results in the server sending: - ADMIN_PACKET_SERVER_CLIENT_JOIN - ADMIN_PACKET_SERVER_CLIENT_INFO - ADMIN_PACKET_SERVER_CLIENT_UPDATE - ADMIN_PACKET_SERVER_CLIENT_QUIT - ADMIN_PACKET_SERVER_CLIENT_ERROR `ADMIN_UPDATE_COMPANY_INFO` results in the server sending: - ADMIN_PACKET_SERVER_COMPANY_NEW - ADMIN_PACKET_SERVER_COMPANY_INFO - ADMIN_PACKET_SERVER_COMPANY_UPDATE - ADMIN_PACKET_SERVER_COMPANY_REMOVE `ADMIN_UPDATE_COMPANY_ECONOMY` results in the server sending: - ADMIN_PACKET_SERVER_COMPANY_ECONOMY `ADMIN_UPDATE_COMPANY_STATS` results in the server sending: - ADMIN_PACKET_SERVER_COMPANY_STATS `ADMIN_UPDATE_CHAT` results in the server sending: - ADMIN_PACKET_SERVER_CHAT `ADMIN_UPDATE_CONSOLE` results in the server sending: - ADMIN_PACKET_SERVER_CONSOLE `ADMIN_UPDATE_CMD_LOGGING` results in the server sending: - ADMIN_PACKET_SERVER_CMD_LOGGING ## 3.1) Polling manually Certain `AdminUpdateTypes` can also be polled: - ADMIN_UPDATE_DATE - ADMIN_UPDATE_CLIENT_INFO - ADMIN_UPDATE_COMPANY_INFO - ADMIN_UPDATE_COMPANY_ECONOMY - ADMIN_UPDATE_COMPANY_STATS - ADMIN_UPDATE_CMD_NAMES Please note the potential gotcha in the "Certain packet information" section below when using the `ADMIN_POLL` packet. `ADMIN_UPDATE_CLIENT_INFO` and `ADMIN_UPDATE_COMPANY_INFO` accept an additional parameter. This parameter is used to specify a certain client or company. Setting this parameter to `UINT32_MAX (0xFFFFFFFF)` will tell the server you want to receive updates for all clients or companies. Not supported `AdminUpdateType` in the poll will result in the server disconnecting the application with `NETWORK_ERROR_ILLEGAL_PACKET`. Additional debug information can be found with a debug level of `net=3`. ## 4.0) Sending rcon commands Rcon runs separate from the `ADMIN_UPDATE_CONSOLE` `AdminUpdateType`. Requesting the execution of a remote console command is done with the packet `ADMIN_PACKET_ADMIN_RCON`. Note: No additional authentication is required for rcon commands. The server will reply with one or more `ADMIN_PACKET_SERVER_RCON` packets. Finally an `ADMIN_PACKET_ADMIN_RCON_END` packet will be sent. Applications will not receive the answer twice if they have asked for the `AdminUpdateType` `ADMIN_UPDATE_CONSOLE`, as the result is not printed on the servers console (just like clients rcon commands). Furthermore, sending a `say` command (or any similar command) will not be sent back into the admin network. Chat from the server itself will only be sent to the admin network when it was not sent from the admin network. Note that when content is queried or updated via rcon, the processing happens asynchronously. But the `ADMIN_PACKET_ADMIN_RCON_END` packet is sent already right after the content is requested as there's no immediate output. Thus other packages and the output of content rcon command may be sent at an arbitrary later time, mixing into the output of other console activity, e.g. also of possible subsequent other rcon commands sent. ## 5.0) Sending chat Sending a `ADMIN_PACKET_ADMIN_CHAT` results in chat originating from the server. Currently four types of chat are supported: - NETWORK_ACTION_CHAT - NETWORK_ACTION_CHAT_CLIENT - NETWORK_ACTION_CHAT_COMPANY - NETWORK_ACTION_SERVER_MESSAGE `NETWORK_ACTION_SERVER_MESSAGE` can be sent to a single client or company using the respective `DestType` and ID. This is a message prefixed with the 3 stars, e.g. `*** foo has joined the game` ## 5.1) Receiving chat Register `ADMIN_UPDATE_CHAT` at `ADMIN_FREQUENCY_AUTOMATIC` to receive chat. The application will be able to receive all chat the server can see. The configuration option `network.server_admin_chat` specifies whether private chat for to the server is distributed into the admin network. ## 6.0) Disconnecting It is a kind thing to say good bye before leaving. Do this by sending the `ADMIN_PACKET_ADMIN_QUIT` packet. ## 7.0) Certain packet information `ADMIN_PACKET_ADMIN_UPDATE_FREQUENCY` and `ADMIN_PACKET_ADMIN_POLL` Potential gotcha: the AdminUpdateType integer type used is a uint16 for `UPDATE_FREQUENCY`, and a uint8 for `POLL`. This is due to boring legacy reasons. It is safe to cast between the two when sending (i.e cast from a uint8 to a uint16). All `ADMIN_PACKET_SERVER_*` packets have an enum value greater 100. `ADMIN_PACKET_SERVER_WELCOME` Either directly follows `ADMIN_PACKET_SERVER_PROTOCOL` or is sent after a new game has been started or a map loaded, i.e. also after ADMIN_PACKET_SERVER_NEWGAME. `ADMIN_PACKET_SERVER_CLIENT_JOIN` and `ADMIN_PACKET_SERVER_COMPANY_NEW` These packets directly follow their respective INFO packets. If you receive a CLIENT_JOIN / COMPANY_NEW packet without having received the INFO packet it may be a good idea to POLL for the specific ID. `ADMIN_PACKET_SERVER_CMD_NAMES` and `ADMIN_PACKET_SERVER_CMD_LOGGING` Data provided with these packets is not stable and will not be treated as such. Do not rely on IDs or names to be constant across different versions / revisions of OpenTTD. Data provided in this packet is for logging purposes only.