Files
DECNET/templates/vnc/server.py
anti f583b3d699 fix(services): Resolve protocol realism gaps and update technical debt register
- Add dynamic challenge nonces to Postgres, VNC, and SIP.
- Add basic keyspace lookup and mock data to Redis.
- Correct MSSQL TDS pre-login offset bounds.
- Support MongoDB OP_MSG handshake version checking.
- Suppress Werkzeug HTTP server headers and normalize FTPAnonymousShell response.
- Add tracking for Dynamic Bait Store (DEBT-027) via DEBT.md.
2026-04-10 02:16:42 -04:00

95 lines
3.0 KiB
Python

#!/usr/bin/env python3
"""
VNC (RFB)server.
Performs the RFB 3.8 handshake, offers VNC authentication, captures the
24-byte DES-encrypted challenge response, then rejects with "Authentication
failed". Logs the raw response for offline cracking.
"""
import asyncio
import os
from decnet_logging import syslog_line, write_syslog_file, forward_syslog
NODE_NAME = os.environ.get("NODE_NAME", "desktop")
SERVICE_NAME = "vnc"
LOG_TARGET = os.environ.get("LOG_TARGET", "")
def _log(event_type: str, severity: int = 6, **kwargs) -> None:
line = syslog_line(SERVICE_NAME, NODE_NAME, event_type, severity, **kwargs)
print(line, flush=True)
write_syslog_file(line)
forward_syslog(line, LOG_TARGET)
class VNCProtocol(asyncio.Protocol):
def __init__(self):
self._transport = None
self._peer = None
self._buf = b""
self._state = "version"
def connection_made(self, transport):
self._transport = transport
self._peer = transport.get_extra_info("peername", ("?", 0))
_log("connect", src=self._peer[0], src_port=self._peer[1])
# Send RFB version
transport.write(b"RFB 003.008\n")
def data_received(self, data):
self._buf += data
self._process()
def _process(self):
if self._state == "version":
if b"\n" not in self._buf:
return
line, self._buf = self._buf.split(b"\n", 1)
client_version = line.decode(errors="replace").strip()
_log("version", src=self._peer[0], client_version=client_version)
# Send security types: 1 type = VNC Authentication (2)
self._transport.write(b"\x01\x02")
self._state = "security_choice"
elif self._state == "security_choice":
if len(self._buf) < 1:
return
chosen = self._buf[0]
self._buf = self._buf[1:]
_log("security_choice", src=self._peer[0], type=chosen)
# Send 16-byte challenge
self._transport.write(os.urandom(16))
self._state = "auth_response"
elif self._state == "auth_response":
if len(self._buf) < 16:
return
response = self._buf[:16]
self._buf = self._buf[16:]
_log("auth_response", src=self._peer[0], response=response.hex())
# SecurityResult: 1 = failed
self._transport.write(b"\x00\x00\x00\x01")
# Failure reason
reason = b"Authentication failed"
import struct
self._transport.write(struct.pack(">I", len(reason)) + reason)
self._transport.close()
def connection_lost(self, exc):
_log("disconnect", src=self._peer[0] if self._peer else "?")
async def main():
_log("startup", msg=f"VNC server starting as {NODE_NAME}")
loop = asyncio.get_running_loop()
server = await loop.create_server(VNCProtocol, "0.0.0.0", 5900) # nosec B104
async with server:
await server.serve_forever()
if __name__ == "__main__":
asyncio.run(main())