Add SSH and TCP keepalive to prevent silent disconnects

- SSH keepalive every 30s with max 3 retries (configurable via env vars)
- TCP keepalive on client sockets to detect dead connections
- Increase pre-auth timeout from 30s to 300s to match TS6 query timeout
- Add keepalive settings to Config dataclass

proxy.py

@@ -4,6 +4,7 @@ import asyncio
 import contextlib
 import logging
 import os
+import socket
 import sys
 from dataclasses import dataclass
 
@@ -23,6 +24,8 @@ class Config:
     ts6_ssh_port: int = 10022
     listen_host: str = "0.0.0.0"
     listen_port: int = 10011
+    ssh_keepalive_interval: int = 30
+    ssh_keepalive_count_max: int = 3
 
     @classmethod
     def from_env(cls) -> Config:
@@ -30,6 +33,8 @@ class Config:
             ts6_host=os.environ.get("TS6_HOST", "teamspeak6"),
             ts6_ssh_port=int(os.environ.get("TS6_SSH_PORT", "10022")),
             listen_port=int(os.environ.get("LISTEN_PORT", "10011")),
+            ssh_keepalive_interval=int(os.environ.get("SSH_KEEPALIVE_INTERVAL", "30")),
+            ssh_keepalive_count_max=int(os.environ.get("SSH_KEEPALIVE_COUNT_MAX", "3")),
         )
 
 TS3_BANNER = (
@@ -57,6 +62,11 @@ class ClientHandler:
     async def handle(self) -> None:
         log.info("Client connected from %s", self.addr)
         try:
+            # Enable TCP keepalive on the client socket
+            sock = self.writer.get_extra_info("socket")
+            if sock:
+                sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
+
             self.writer.write(TS3_BANNER)
             await self.writer.drain()
             await self._auth_loop()
@@ -71,7 +81,7 @@ class ClientHandler:
 
     async def _auth_loop(self) -> None:
         while True:
-            line = await asyncio.wait_for(self.reader.readline(), timeout=30)
+            line = await asyncio.wait_for(self.reader.readline(), timeout=300)
             if not line:
                 return
             cmd = line.decode("utf-8", errors="replace").strip()
@@ -124,6 +134,8 @@ class ClientHandler:
                     username=username,
                     password=password,
                     known_hosts=None,
+                    keepalive_interval=self.config.ssh_keepalive_interval,
+                    keepalive_count_max=self.config.ssh_keepalive_count_max,
                 ),
                 timeout=10,
             )
@@ -144,7 +156,11 @@ class ClientHandler:
                 except TimeoutError:
                     break
 
-            log.info("SSH session established for %s", self.addr)
+            log.info(
+                "SSH session established for %s (keepalive=%ds)",
+                self.addr,
+                self.config.ssh_keepalive_interval,
+            )
             return True
         except asyncssh.PermissionDenied:
             log.warning("SSH auth failed for %s (bad credentials)", self.addr)
@@ -242,6 +258,11 @@ async def main() -> None:
     )
     log.info("TS3 Query Proxy listening on %s:%d", config.listen_host, config.listen_port)
     log.info("Forwarding to %s:%d (SSH Query)", config.ts6_host, config.ts6_ssh_port)
+    log.info(
+        "SSH keepalive: interval=%ds, max_count=%d",
+        config.ssh_keepalive_interval,
+        config.ssh_keepalive_count_max,
+    )
     async with server:
         await server.serve_forever()