chore: remove arbitrary default max connections limit

When NGIT_MAX_CONNECTIONS is unset the relay imposes no connection cap,
deferring to OS fd limits and infrastructure controls. The option remains
available for operators who want an explicit ceiling.

.env.example

@@ -298,7 +298,7 @@
 # ============================================================================
 
 # Maximum total connections to the relay
-# Prevents connection exhaustion DoS attacks
+# When unset (default), connections are unlimited (defers to OS fd limits and infrastructure controls)
 # CLI: --max-connections <count>
-# Default: 4096
+# Default: unlimited
 # NGIT_MAX_CONNECTIONS=4096

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- Remove arbitrary default max connections limit; when `NGIT_MAX_CONNECTIONS` is unset the relay imposes no connection cap, deferring to OS fd limits and infrastructure controls
+
 ## [1.0.1] - 2026-02-27
 
 ### Fixed

docs/reference/configuration.md

@@ -997,15 +997,15 @@ Event blacklist does **not** affect NIP-11 metadata:
 
 #### `NGIT_MAX_CONNECTIONS`
 
-**Description:** Maximum total connections to the relay. Prevents connection exhaustion DoS attacks.  
+**Description:** Maximum total connections to the relay. When unset, connections are unlimited, deferring to OS fd limits and infrastructure-level controls.  
 **Type:** Integer  
-**Default:** `4096`  
+**Default:** unlimited  
 **Required:** No
 
 **Examples:**
 
 ```bash
-# Default: 4096 connections
+# Cap connections for a resource-constrained deployment
 NGIT_MAX_CONNECTIONS=4096
 
 # Higher limit for large public relay
@@ -1017,8 +1017,8 @@ NGIT_MAX_CONNECTIONS=100
 
 **Notes:**
 
-- Limits total concurrent WebSocket connections to the relay
-- Prevents connection exhaustion attacks
+- When unset, the relay imposes no connection limit (`Semaphore::MAX_PERMITS`); OS fd limits and infrastructure controls apply
+- Set this only if you need an explicit cap; otherwise leave unset
 - Works in conjunction with per-connection limits (500 subscriptions, 60 events/min)
 - When limit is reached, new connections are rejected
 - Existing connections continue to work normally

nix/module.nix

@@ -268,9 +268,10 @@ let
       };
 
       maxConnections = mkOption {
-        type = types.int;
-        default = 4096;
-        description = "Maximum total connections to the relay";
+        type = types.nullOr types.int;
+        default = null;
+        description =
+          "Maximum total connections to the relay (default: unlimited, defers to OS/infrastructure limits)";
       };
 
       user = mkOption {
@@ -337,8 +338,9 @@ let
       NGIT_REPOSITORY_WHITELIST = concatStringsSep "," cfg.repositoryWhitelist;
       NGIT_REPOSITORY_BLACKLIST = concatStringsSep "," cfg.repositoryBlacklist;
       NGIT_EVENT_BLACKLIST = concatStringsSep "," cfg.eventBlacklist;
-      NGIT_MAX_CONNECTIONS = toString cfg.maxConnections;
       NGIT_LOG_LEVEL = cfg.logLevel;
+    } // optionalAttrs (cfg.maxConnections != null) {
+      NGIT_MAX_CONNECTIONS = toString cfg.maxConnections;
     } // optionalAttrs (cfg.relayName != null) {
       NGIT_RELAY_NAME = cfg.relayName;
     } // optionalAttrs (cfg.archiveReadOnly != null) {

src/config.rs

@@ -466,10 +466,9 @@ pub struct Config {
     #[arg(long, env = "NGIT_EVENT_BLACKLIST", default_value = "")]
     pub event_blacklist: String,
 
-    /// Maximum total connections to the relay (default: 4096)
-    /// Prevents connection exhaustion DoS attacks
-    #[arg(long, env = "NGIT_MAX_CONNECTIONS", default_value_t = 4096)]
-    pub max_connections: usize,
+    /// Maximum total connections to the relay (default: unlimited, defers to OS/infrastructure limits)
+    #[arg(long, env = "NGIT_MAX_CONNECTIONS")]
+    pub max_connections: Option<usize>,
 
     /// Log level for application logging
     #[arg(long, env = "NGIT_LOG_LEVEL", default_value = "info")]
@@ -755,7 +754,7 @@ impl Config {
             repository_whitelist: String::new(),
             repository_blacklist: String::new(),
             event_blacklist: String::new(),
-            max_connections: 500,
+            max_connections: None,
             log_level: "debug".to_string(),
         }
     }

src/nostr/builder.rs

@@ -736,7 +736,7 @@ pub async fn create_relay(
     let write_policy =
         Nip34WritePolicy::new(database.clone(), &git_data_path, purgatory, config.clone());
 
-    let relay = LocalRelayBuilder::default()
+    let mut builder = LocalRelayBuilder::default()
         .database(database.clone())
         .write_policy(write_policy.clone())
         // Explicitly set rate limits (make defaults visible in code)
@@ -744,10 +744,13 @@ pub async fn create_relay(
         .rate_limit(RateLimit {
             max_reqs: 500,        // Max concurrent subscriptions per connection
             notes_per_minute: 60, // Max events per minute per connection
-        })
-        // Total connection limit to prevent DoS attacks
-        .max_connections(config.max_connections)
-        .build();
+        });
+
+    if let Some(max) = config.max_connections {
+        builder = builder.max_connections(max);
+    }
+
+    let relay = builder.build();
 
     tracing::info!(
         "Relay configured with GRASP-01 validation for domain: {}",