Linux server docs: preset, README-linux, systemd unit

CMakePresets.json

@@ -11,6 +11,15 @@
         "VCLibPackagePath": "${sourceDir}/build/no-vcpkg/vcpkg.user"
       },
       "toolset": "v143"
+    },
+    {
+      "name": "linux-x64",
+      "displayName": "Linux x64 (dedicated server only)",
+      "generator": "Unix Makefiles",
+      "binaryDir": "${sourceDir}/build/linux",
+      "cacheVariables": {
+        "CMAKE_BUILD_TYPE": "Release"
+      }
     }
   ],
   "buildPresets": [
@@ -18,6 +27,10 @@
       "name": "release",
       "configurePreset": "vs2022-x64",
       "configuration": "Release"
+    },
+    {
+      "name": "linux-release",
+      "configurePreset": "linux-x64"
     }
   ]
 }

Server/README-linux.md

@@ -0,0 +1,80 @@
+# ReSkate dedicated server on Linux
+
+Native x86_64 build. Same lobby protocol as `ReSkateServer.exe`; needs no game install.
+Self-update is disabled on Linux (V1) — update by replacing the binary.
+
+## Requirements
+
+- 64-bit Linux (tested: CachyOS/Arch, Ubuntu 22.04+ should work).
+- `cmake >= 3.24`, `g++ >= 12` (C++20), `libssl-dev` (OpenSSL), `libcurl` headers optional (not needed for V1).
+- Steamworks SDK redist beside the binary: `libsteam_api.so` + `steamclient.so`
+  (Valve proprietary, not in this repo). Anonymous game-server login, same as Windows.
+
+Arch/CachyOS:
+
+```sh
+sudo pacman -S base-devel cmake openssl
+```
+
+Ubuntu/Debian:
+
+```sh
+sudo apt install build-essential cmake libssl-dev
+```
+
+## Build
+
+```sh
+cmake --preset linux-x64
+cmake --build --preset linux-release -j$(nproc)
+./build/linux/ReSkateServer
+```
+
+Binary: `build/linux/ReSkateServer` (ELF, `OUTPUT_NAME ReSkateServer`).
+
+Portable tests:
+
+```sh
+cmake --preset linux-x64 -DDINGOSDK_BUILD_MULTIPLAYER_TESTS=ON
+cmake --build --preset linux-release -j$(nproc)
+ctest --test-dir build/linux --output-on-failure
+```
+
+Expected: 8 passed (`multiplayer_parties`, `server_activity`, `server_speed_check`,
+`server_config`, `word_filter`, `multiplayer_bandwidth`, `multiplayer_lanes`,
+`multiplayer_prediction`). Windows-only tests (voice, lobbies, UI) stay `WIN32`-gated.
+
+## Run
+
+1. Put `ReSkateServer` in its own folder with `libsteam_api.so`, `steamclient.so`.
+2. First run writes `ReSkateServer.json`; edit `name` + `admins`, restart.
+3. Optional: `world-layers.json` (export on Windows via
+   `ReSkateServer.exe --export-world-layers "<Skate folder>" world-layers.json`),
+   `Mods/<mod>/reskate-levels.json` for custom maps.
+4. No ports need opening (Steam relay). Optional UDP `27015-27016` (`port`,
+   `query_port`) for browser ping + faster joins.
+
+Without `libsteam_api.so` the server exits 1 with:
+`Cannot load .../libsteam_api.so. Put libsteam_api.so (Steamworks SDK) next to the server.`
+
+Full command list: `Server/README.txt` (same on Linux; binary name differs).
+
+## systemd
+
+See `contrib/reskate-server.service`. Install:
+
+```sh
+sudo cp contrib/reskate-server.service /etc/systemd/system/
+sudo systemctl daemon-reload
+sudo systemctl enable --now reskate-server
+```
+
+## Notes / limits (V1)
+
+- `auto_update` / `update` command: `updates_enabled()==false` on Linux.
+  `check_for_update` reports “self-update is not supported on Linux”.
+- `--export-world-layers` needs Windows game + Oodle (`oo2core_9_win64.dll`);
+  on Linux Oodle blocks throw. Export on Windows, copy the JSON over.
+- `content_cache` dir: `%LOCALAPPDATA%` on Windows, `$XDG_CACHE_HOME`/`~/.cache` on Linux.
+- Crypto interop verified: OpenSSL `PKCS5_PBKDF2_HMAC(SHA256, 100k)` +
+  `HMAC-SHA256` matches Windows `BCrypt` (checked against Python `hashlib`).

contrib/reskate-server.service

@@ -0,0 +1,19 @@
+[Unit]
+Description=ReSkate dedicated server
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+Type=simple
+User=reskate
+WorkingDirectory=/opt/reskate-server
+ExecStart=/opt/reskate-server/ReSkateServer
+Restart=always
+RestartSec=5
+# Server uses restart_for_update internally; V1 Linux has self-update off,
+# so any non-zero exit still restarts here.
+StandardOutput=append:/opt/reskate-server/ReSkateServer.log
+StandardError=inherit
+
+[Install]
+WantedBy=multi-user.target