Highly Performant & Scalable Ultima Online Server Emulator
https://www.modernuo.com
c-sharpcsharpcsharp-coredotnetdotnet-coreemulatorgplgplv3mmommo-enginemmorpgmmorpg-serveronlinerpgrunuoserverservuoultimaultima-onlineuo
b2c59191bd
> ⚠️ **Rollback hazard — one-way door once logins are taken.** Serialization is unchanged, so a save > written by this build still *loads* on the previous one. Its contents do not survive the trip: on > its first successful login each account is rehashed to `$argon2id$`, and the previous build ships > Argon2.Bindings 1.19.0, whose `Verify` is gated by the verifier's own configured type and answers > `false` for an `$argon2id$` hash. **After a shard running this build has accepted logins, do not > roll back past this commit** — every account that logged in is locked out on the older binary, and > the only recovery is rolling forward again or resetting passwords by hand. Roll back only from a > save taken before the first post-deploy login. Requires [Argon2.Bindings 1.20.0](https://github.com/modernuo/Argon2.Bindings/pull/14), now published. ## What - Consume `Argon2.Bindings` 1.20.0, which resolves the Argon2 type from the stored PHC string rather than from the verifier's own configuration. - Default to **Argon2id, m=16384, t=1, p=1** — 8.51 ms against the old Argon2i 8 MiB t=3 at 10.11 ms. Cheaper *and* stronger. - Rehash on a successful login whenever the stored parameters are stale, not only when the algorithm changes. - Fix `SetPassword`, which derived the password phrase from the outgoing algorithm while storing it under the incoming one. ## Why **Verification was gated by the verifier's configured type.** `Verify` passed the instance's own `ArgonType` to native `argon2_verify`, whose `decode_string` rejects a disagreeing `$argon2i$`/`$argon2id$` prefix and returns `DECODING_FAIL` — folded into `false`, the same answer as a wrong password. Switching the default type would have locked out every existing account, and `VerifyAndUpdate` could not have migrated them either: it delegates to the same type-fixed `Verify` and never compared `ArgonType`. Fixed upstream in 1.20.0. The pinned legacy-`$argon2i$` test here fails on 1.19.0 for exactly that reason, which is what makes the package bump load-bearing rather than incidental. **Changing the defaults would otherwise have reached nobody.** Argon2's PHC string embeds `m`, `t` and `p`, so verification uses the parameters stored with each account, not the configured ones — and verification is the hot path. `CheckPassword` only rehashed when the *algorithm* changed, never when its cost parameters did, so on an established shard the new defaults would have applied to new accounts only. `IPasswordProtection.NeedsRehash` closes that: it defaults to `false`, so PBKDF2 and the `HashAlgorithm` protections are untouched — only Argon2 carries its cost inside the stored value. **`SetPassword` picked the phrase rule from the wrong algorithm.** SHA1 and SHA2 salt the phrase with the username; Argon2 and PBKDF2 do not. It chose the rule from the *outgoing* algorithm while storing under the *incoming* one, so any algorithm change wrote a credential its own next verify could not reproduce. It now assigns `PasswordAlgorithm` first and derives the phrase from that. Note this ordering is load-bearing and invisible — `UpgradingAlgorithm_DoesNotLockTheAccountOut` is what pins it. ## Cost Verification is re-derivation, so these are login numbers. A full login calls `CheckPassword` twice — `AccountLogin` (0x80) then `GameLogin` (0x91): **~20 ms before, ~17 ms after**, plus a one-time ~8.5 ms rehash on each account's migrating login. That cost is still paid on the game loop. Moving hashing off-loop is deliberately **not** in this PR — it needs a pending-auth state in the login handlers, bounding of in-flight hashes, and login rate limiting. |
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| FAQ.md | ||
| GEMINI.md | ||
| global.json | ||
| LICENSE | ||
| ModernUO.slnx | ||
| publish.cmd | ||
| publish.ps1 | ||
| publish.sh | ||
| README.md | ||
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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
Interactive Mode (Recommended for new users)
Run ./publish.cmd (Windows) or ./publish.sh (Linux/macOS) with no arguments to launch the guided build tool. It will:
- Check prerequisites (.NET SDK, native libraries)
- Walk you through configuration and platform selection
- Build and publish the server to the
Distributiondirectory - Show deployment instructions for cross-compiled builds
Command Line
./publish.cmd [release|debug] [os] [arch]
os- Supported operating systemsarchx64- Intel/AMD 64-bitarm64- ARM 64-bit
Linux Prerequisites
Fedora, CentOS, RHEL, AlmaLinux, Rocky, etc
dnf upgrade --refresh -y
# RHEL-family distributions (CentOS Stream, AlmaLinux, Rocky, RHEL) need CRB and EPEL enabled.
# Fedora skips this block.
dnf install -y dnf-plugins-core
dnf config-manager --set-enabled crb
dnf install -y epel-release
# Prerequisites
dnf install -y findutils libicu libdeflate libargon2 tzdata
Ubuntu, Debian, etc
apt-get update -y
# The ICU runtime package carries the ABI version in its name (libicu74, libicu76, …) and has no
# stable alias, so match it by pattern rather than pinning a release-specific name.
apt-get install -y '^libicu[0-9]+$' libdeflate0 libargon2-1 tzdata
Only the runtime libraries are needed — the -dev/-devel packages are not. Run
./build-tool --check-prereqs to check the current machine and print the exact packages your
release needs.
zstd is not listed because ZstdNet bundles libzstd for every platform, and liburing is not
listed because IORingGroup issues io_uring syscalls directly.
If the shard's configured time zone is a legacy alias such as US/Eastern, Debian 12 and Ubuntu
24.04 also need tzdata-legacy. See Platform Prerequisites
for what each dependency is for and what breaks without it.
OSX Requirements
brew install icu4c libdeflate argon2
Running the Server
- Follow the publish instructions
- The
Distributiondirectory is portable — copy it to your production server for deployment - Run
ModernUO.exeordotnet ModernUO.dllfrom theDistributiondirectory - On first run, the server will prompt you to configure game data file locations
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
Development Tools & Plugins provided with ♥ by
Code Signing Policy
Free code signing provided by SignPath.io, certificate by SignPath Foundation.
This program will not transfer any information to other networked systems unless specifically requested by the user or the person installing or operating it
Teams & Roles
Approvers & Committers: Development Team