927c87702d
The shard owner, on a Starlink CGNAT address, was blocked by the imported reputation blocklist. The cause was not CrowdSec: the address was a literal line in ip-blocklist.txt, so BlocklistFilter denied it at accept and then promoted it. Clearing the CrowdSec decision could not fix it either, because the file entry re-reports within promoteSuppression of every reconnect. Reputation feeds list shared consumer address space constantly. On CGNAT one public address fronts many subscribers at the same time, so a single abusive customer gets the address listed and everyone else behind it is blocked with them; where leases rotate, a listing says little about whoever holds the address now. So exemptions go where they cost nothing, and escalation is driven by what a connection actually does. GENERATOR (tools/Export-IpBlocklist.ps1) - -AllowlistFile takes multiple paths, subtracted from the merged set before the output is written. Defaults to the operator's own ip-allowlist.txt (created once, never rewritten) plus one generated file per network carve-out. - Subtraction is range-correct: an allowlisted address inside a blocked CIDR splits that CIDR around the hole instead of being ignored. This also fixes -ExcludeAnonymizers, which parsed CIDR entries and then only subtracted singles. - Carve-outs are a table (name, ASN, reason, offline seed) rather than a hardcoded network, so covering another CGNAT provider is one row. -RefreshCarveouts re-fetches from the ASN's current routing announcements and collapses them; -Carveout '' subtracts none. Announcements rather than ownership records, because registry data disagrees with what is routed and caps its result sets. - Editing an allowlist bypasses -MinInterval, so a just-added exemption is not indistinguishable from the allowlist not working. - The shipped starlink carve-out costs ~0.1% of the list. ALLOWLISTS - FileAllowlist reads the same files the generator subtracts, so an operator entry means "leave this address alone" for real. Subtraction alone only covers being BLOCKED; behavioural detections never consult the blocklist, so without this a carve-out was quietly routed around and one scanner behind a shared address was enough to get everyone behind it firewalled. Reading the files also means an entry applies on the next reload rather than the next regeneration. - LoginAllowlist is earned by authenticating, with a 90 day TTL because an address that logged in years ago is a stranger. Its own store rather than Account.LoginIPs, which has no timestamps and cannot be backfilled. An entry is evidence rather than a licence: 10 suppressed contributions in an hour revokes it, and a fresh login forgives the tally. - Both are consulted only AFTER the blocklist has already matched, so a normal accept pays nothing for them and the accept gate stays allowlist-free. - BanExemptions combines them behind BanChannel.IsExempt. Suppresses escalation only; every local defence still applies. BEHAVIOURAL DETECTION - silent-connect (reaped having sent zero bytes) and invalid-seed (a zero seed) are contributed. Both were already disconnected. - ForeignProtocol positively identifies HTTP, TLS and SSH. Asking "is this a good UO client?" cannot work: LoginEncryption.ClientDecrypt is a byte-for-byte stream XOR, so a client with encryption on when the shard expects none sends a structurally perfect connection whose payload is noise. Nothing assumes arrival framing, since TCP has no message boundaries and a rule of the form "these bytes must arrive together" drops real players on poor links. - Keyed on bytes-received rather than elapsed time throughout. A connection that sent something and ran out of time is far more likely a slow link, and banning those makes the player retry, trip the rate limiter, and compound it. - AutoDenylist holds behavioural detections locally for 15 minutes, as an IConnectionFilter plus IBanReporter over one store so engine detection sites never reach into content. Closes the gap where a flood pays for a socket and a NetState per connection while waiting for an OS bouncer, and is the whole defence on a shard running none. Not persisted: a holding pen that survives restarts is a ban without a ban's review. - BanReasons centralises the slugs. IsBehavioral is an opt-in set, not "everything except manual", so a future reason escalates normally instead of silently inheriting an exemption. The first cut of the exemption swallowed manual admin bans; this is why. FIXES - BanConfiguration.Settings was null until Configure() ran while the reap path dereferences it every Slice(), so a harness driving NetState.Slice() directly hit an NRE that looked flaky because it depended on test ordering. - -AllowlistFile was typed [string] while documented and used as a list. LAYOUT AND DOCS Content network code moves out of Misc into UOContent/Network, one concern per folder. Namespaces are untouched, so these are pure file moves. dev-docs/ip-bans-and-allowlists.md documents the subsystem, leading with the operator process for unblocking a player -- including the three things that look sufficient and are not: deleting the CrowdSec decision alone, editing ip-blocklist.txt by hand, and cscli allowlists alone. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
81 lines
3.4 KiB
C#
81 lines
3.4 KiB
C#
/*************************************************************************
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* ModernUO *
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* Copyright 2019-2026 - ModernUO Development Team *
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* Email: hi@modernuo.com *
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* File: AutoDenylistConfiguration.cs *
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* *
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* This program is free software: you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation, either version 3 of the License, or *
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* (at your option) any later version. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program. If not, see <http://www.gnu.org/licenses/>. *
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*************************************************************************/
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using System;
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using System.IO;
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using System.Text.Json.Serialization;
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using Server.Json;
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namespace Server.Network;
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/// <summary>
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/// Loads the <see cref="AutoDenylistSettings"/> from <c>Configuration/auto-denylist.json</c> (matching the
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/// per-feature JSON config pattern used by <c>BlocklistConfiguration</c>). Loaded once; a missing file writes
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/// a template so operators have something to edit.
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/// </summary>
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public static class AutoDenylistConfiguration
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{
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private const string _path = "Configuration/auto-denylist.json";
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public static AutoDenylistSettings Settings { get; private set; }
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public static void Load()
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{
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var path = Path.Join(Core.BaseDirectory, _path);
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if (File.Exists(path))
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{
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Settings = JsonConfig.Deserialize<AutoDenylistSettings>(path);
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}
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else
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{
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Settings = new AutoDenylistSettings();
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Save();
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}
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}
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private static void Save()
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{
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JsonConfig.Serialize(Path.Join(Core.BaseDirectory, _path), Settings);
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}
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}
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/// <summary>Bound configuration for <see cref="AutoDenylist"/>.</summary>
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public record AutoDenylistSettings
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{
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/// <summary>Whether behavioural detections are held locally. Disabled makes the filter inert.</summary>
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[JsonPropertyName("enabled")]
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public bool Enabled { get; set; } = true;
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/// <summary>
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/// How long an address is denied at accept after the shard catches it misbehaving. Deliberately
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/// independent of the duration reported to external bouncers: this is a local holding pen, not a ban.
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/// </summary>
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/// <remarks>
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/// Short on purpose: it covers the gap before an OS bouncer reacts, and blunts a flood on shards running
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/// none. An address still attacking is simply re-detected and re-added, so the list sustains itself while
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/// a mistake clears on its own.
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/// </remarks>
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[JsonPropertyName("duration")]
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public TimeSpan Duration { get; set; } = TimeSpan.FromMinutes(15);
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/// <summary>
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/// Hard cap on tracked addresses: a distinct-source flood is the case this exists for, so the cap is what
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/// stops it becoming the exhaustion it prevents. At the cap new addresses are not tracked, but are still
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/// disconnected by whichever gate detected them.
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/// </summary>
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[JsonPropertyName("maxEntries")]
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public int MaxEntries { get; set; } = 65536;
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}
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