Highly Performant & Scalable Ultima Online Server Emulator
https://www.modernuo.com
c-sharpcsharpcsharp-coredotnetdotnet-coreemulatorgplgplv3mmommo-enginemmorpgmmorpg-serveronlinerpgrunuoserverservuoultimaultima-onlineuo
> [!IMPORTANT] > **Breaking Changes** > - DecodePacket and EncodePacket delegates replaced with IClientEncryption interface > - NetState.Connection (Socket) replaced with internal RingSocket management > - NetState.RecvPipe and NetState.SendPipe removed (buffers managed internally) ## Summary Upgrades the networking stack from PollGroup-based I/O to io_uring, significantly improving I/O performance on Linux. This also adds native client encryption support for encrypted UO clients. ## Major Changes io_uring Networking Architecture - Replaced PollGroup with IORingGroup for async socket I/O operations - Removed Pipe.cs (mirrored ring buffer) and TcpServer.cs in favor of RingSocketManager - Added NetState.Network.cs - centralized network infrastructure handling accept, recv, send, and disconnect completions - Added SocketHelper.cs - platform-specific socket utilities for raw socket handle operations (getpeername, getsockname) - Buffer management now handled by RingSocketManager with configurable slab allocation ### Client Encryption Support - Added full encryption stack in Network/Encryption/: - EncryptionConfig.cs - configurable encryption modes (None, Unencrypted, Encrypted, Both) - EncryptionManager.cs - encryption detection and initialization for login/game packets - LoginEncryption.cs - handles login packet encryption with version-derived keys - GameEncryption.cs - handles game server encryption using Twofish - TwofishEngine.cs - optimized Twofish block cipher implementation - LoginKeys.cs - encryption key table for client versions - IClientEncryption.cs - interface for client encryption implementations ### NetState Improvements - Replaced Socket Connection with RingSocket _socket for managed socket lifecycle - Changed from GCHandle polling to event-based completion processing - Disconnect handling now properly waits for pending sends to flush - Simplified connecting socket management using lazy queue removal ### Configuration - New settings: network.encryptionMode and network.encryptionDebug - Encryption mode flags: Unencrypted, Encrypted, or Both ### Dependencies - Replaced PollGroup NuGet package with IORingGroup - Linux requires liburing-dev / liburing-devel package ### Test plan - Verify server starts and accepts connections on Linux with io_uring - Verify server starts and accepts connections on Windows (fallback to IOCP) - Test unencrypted client connections (ClassicUO with encryption disabled) - Test encrypted client connections if available - Verify graceful disconnect flushes pending data - Confirm CI builds pass on all target platforms |
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| .github | ||
| Distribution/Data | ||
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| Projects | ||
| .editorconfig | ||
| .gitattributes | ||
| .gitignore | ||
| azure-pipelines.yml | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| Directory.Build.props | ||
| FAQ.md | ||
| global.json | ||
| LICENSE | ||
| mkdocs.yml | ||
| ModernUO.sln | ||
| publish.cmd | ||
| publish.sh | ||
| README.md | ||
| rider-settings.zip | ||
| Rules.ruleset | ||
| SPONSORS.md | ||
| stylecop.json | ||
| THIRD-PARTY-NOTICES | ||
| version.json | ||
ModernUO

Ultima Online Server Emulator for the modern era!
Requirements
Supported Operating Systems
Required Frameworks
All Operating Systems
Windows
Development
Supported IDEs
Getting Started
- Install prerequisite requirements
- Clone this repository (or download the latest):
git clone https://github.com/modernuo/ModernUO.git
- Open
ModernUO.slnto start developing
Building/Publishing
- Run
./publish.cmd [release|debug (default: release)] [os] [arch (default: x64)]os- Supported operating systemsarchx64- Intel/AMD 64-bitarm64- ARM 64-bit (Windows not supported)
Linux Prerequisites
Fedora, CentOS, RHEL, etc
dnf upgrade --refresh -y
# CentOS does not come with EPEL enabled
dnf install -y epel-release epel-next-release
dnf install -y findutils libicu libdeflate-devel zstd libargon2-devel liburing-devel
Ubuntu, Debian, etc
apt-get update -y
apt-get install -y libicu-dev libdeflate-dev zstd libargon2-dev liburing-dev
OSX Requirements
brew install icu4c libdeflate zstd argon2
Running the Server
- Follow the publish instructions
- Run
ModernUO.exeordotnet ModernUO.dllfrom theDistributiondirectory
Troubleshooting / FAQ
- See FAQ
Want to sponsor?
Thank you for supporting us! You can find out how by visiting the sponsors page.
Collaborators
Thanks
- RunUO Team & Community
- Voxpire, the ServUO Team & Community
- Karasho, Jaedan and the ClassicUO Community