diff --git a/multiplayer.md b/multiplayer.md new file mode 100644 --- /dev/null +++ b/multiplayer.md @@ -0,0 +1,207 @@ +# Multiplayer manual for OpenTTD + +## Table of contents + +- 1.0) [Starting a server](#10-starting-a-server) +- 2.0) [Connecting to a server](#20-connecting-to-a-server) + - 2.1) [Connecting to a server over the console](#21-connecting-to-a-server-over-the-console) +- 3.0) [Playing internet games](#30-playing-internet-games) +- 4.0) [Tips for servers](#40-tips-for-servers) + - 4.1)[Imposing landscaping limits](#41-imposing-landscaping-limits) +- 5.0) [Some useful things](#50-some-useful-things) +- 6.0) [Troubleshooting](#60-troubleshooting) + + +## 1.0) Starting a server + +- Click on "Multiplayer" in the Start Menu. +- Click on "Start Server". +- Give your server a name. +- Select the visibility of your server: + - "Public": your server will be publicly listed. + - "Invite Only": only players who have the invite code for your server can + join. + - "Local": only players on your local network can join. +- (optional) Set a password for your server. +- Click "New Game", "Load Game", or "Play Scenario". +- Start playing. + +## 2.0) Connecting to a server + +- Click on "Multiplayer" in the Start Menu. +- There are three ways to join a server: + - If you want to connect to a local server, click "Search LAN". + - If you want to connect to a public game, click "Search internet". + - If the server-owner shared an invite code with you: + - Click "Add Server". + - Fill in the invite code, which always starts with a `+`. + - Click "OK". +- Click on the server you want to join. +- Click "Join Game". +- If the server has a password, it will ask you for this. +- You see a progressbar how far you are with joining the server. +- Happy playing. + +## 2.1) Connecting to a server over the console + +- Open the console and type `connect` for help how to connect via the console. + +## 3.0) Playing internet games + +- Servers with a red dot behind it have a different version then you have. You + will not be able to join those servers. + +- Servers with a yellow dot behind it have NewGRFs that you do not have. You + will not be able to join those servers. However, via "NewGRF Settings" and + "Find missing content online" you might be able to download the needed + NewGRFs after which you can join the server. + +- It can happen that a connection is that slow, or you have that many clients + connected to your server, that your clients start to loose their connection. + Some things you can do about it: + - `[network] frame_freq`: + change it in console with: `set network.frame_freq ` + the number should be between the 0 and 10, not much higher. It indicates + the delay between clicking and showing up. The higher, the more you notice + it, but the less bandwidth you use. + A good value for Internet-games is 2 or 3. + + - `[network] sync_freq`: + change it in console with: `set network.sync_freq ` + the number should be between the 50 and 1000, not much lower, not much + higher. It indicates the time between sync-frames. A sync-frame is a frame + which checks if all clients are still in sync. When the value it too high, + clients can desync in 1960, but the server detects it in 1970. Not really + handy. The lower the value, the more bandwidth it uses. + + NB: changing `frame_freq` has more effect on the bandwidth then `sync_freq`. + +## 4.0) Tips for servers + +- You can launch a dedicated server by adding `-D` as parameter. +- In UNIX like systems, you can fork your dedicated server by adding `-f` as + parameter. + +- You can automatically clean companies that do not have a client connected to + them, for, let's say, 3 years. You can do this via: `set autoclean_companies` + and `set autoclean_protected` and `set autoclean_unprotected`. Unprotected + removes a password from a company when it is not used for more then the + defined amount of months. `set autoclean_novehicles` can be used to remove + companies without any vehicles quickly. + +- You can also do this manually via the console: `reset_company`. + +- You can let your server automatically restart a map when, let's say, + year 2030 is reached. See `set restart_game_date` for detail. + +- If you want to be on the server-list, make your server public. You can do + this either from the Start Server window, via the in-game Online Players + window, or by typing in the console: `set server_game_type public`. + +- You can protect your server with a password via the console: `set server_pw`, + or via the Start Server menu. + +- When you have many clients connected to your server via Internet, watch your + bandwidth (if you have any limit on it, set by your ISP). One client uses + about 1.5 kilobytes per second up and down. To decrease this amount, setting + `frame_freq` to 1 will reduce it to roughly 1 kilobyte per second per client. + +- OpenTTD's default settings for maximum number of clients, and amount of data + from clients to process are chosen to not influence the normal playing of + people, but to prevent or at least make it less likely that someone can + perform a (distributed) denial-of-service attack on your server by causing + an out-of-memory event by flooding the server with data to send to all + clients. The major factor in this is the maximum number of clients; with + 32 clients "only" sending one chat message causes 1024 messages to be + distributed in total, with 64 clients that already quadruples to 4096. Given + that upstream bandwidth is usually the limiting factor, a queue of packets + that need to be sent will be created. + To prevent clients from exploiting this "explosion" of packets to send we + limit the number of incoming data, resulting in effectively limiting the + amount of data that OpenTTD will send to the clients. Even with the default + limits it is possible to generate about 70.000 packets per second, or about + 7 megabit per second of traffic. + Given that OpenTTD kicks clients after they have not reacted within about 9 + seconds from sending a frame update packet it would be possible that OpenTTD + keeps about 600.000 packets in memory, using about 50 megabytes of memory. + Given that OpenTTD allows short bursts of packets, you can have slightly + more packets in memory in case of a distributed denial of service attack. + When increasing the amount of incoming data, or the maximum number of + clients the amount of memory OpenTTD needs in case of a distributed denial + of service attack is linearly related to the amount of incoming data and + quadratic to the amount of clients. In short, a rule of thumb for, the + maximum memory usage for packets is: + `#max_clients * #max_clients * bytes_per_frame * 10 KiB`. + +### 4.1) Imposing landscaping limits + +- You can impose limits on companies by the following 4 settings: + - `terraform_per_64k_frames` + - `terraform_frame_burst` + - `clear_per_64k_frames` + - `clear_frame_burst` + +- Explaining `NNN_burst` and `NNN_per_64K_frames` + - `NNN_burst` defines 3 things, the maximum limit, the limit of a single + action, and the initial value for the limit assigned to a new company. + This setting is fairly simple and requires no math. + + A value of 1 means a single tile can be affected by a single action. + This results in having to click 400 times when wanting to cover an area + of 20 x 20 tiles. + + The default value 4096 covers an area of 64 x 64 tiles. + + - `NNN_per_64K_frames` defines the number of tiles added to each companies + limit per frame (however not past the possible maximum value,the + `NNN_burst`). 64k rather resembles the exact number of 65536 frames. So + setting this variable to 65536 means: `65536 / 65536 = 1 tile per frame`. + + As a day consists of 74 frames, a company's limit is increased by 74 + tiles during the course of a single day (2.22 seconds). + To achieve a 1 tile per day increase the following calculation is needed: + `1 / 74 (frames per day) * 65536 (per_64k_frames) = 885.62...`. + After rounding: a value of 886 means adding a bit over 1 tile per day. + + There is still enough space to scale this value downwards: + decreasing this value to 127 results in a bit over 1 tile added to the + allowance per week (7 days). + + To create a setup in which a company gets an initial allowance only, + set the value to 0 - no increase of the allowance per frame. + +- Even though construction actions include a clear tile action, they are not + affected by the above settings. + +## 5.0) Some useful things + +- You can protect your company so nobody else can join uninvited. To do this, + set a password in your Company window. + +- You can chat with other players via ENTER or via SHIFT+T or via the Online + Players window + +- Servers can kick players, so don't make them use it! + +## 6.0) Troubleshooting + +### My server does not show up in the serverlist + +Check if the visibility of your server is set to `public`. + +If it is, and your server still isn't showing up, start OpenTTD with +`-d net=4` as extra argument. This will show debug message related to the +network, including communication to/from the Game Coordinator. + +### My server warns a lot about getaddrinfo taking N seconds + +This could be a transient issue with your (local) DNS server, but if the +problem persists there is likely a configuration issue in DNS resolving on +your computer. + +#### Running OpenTTD in a Docker container? + +This is an issue with dual-stack Docker containers. If there is no default +IPv6 resolver and IPv6 traffic is preferred, DNS requests will time out after +5 seconds. To resolve this, use an IPv4 DNS server for your Docker container, +for example by adding `--dns 1.1.1.1` to your `docker run` command.