Files
DECNET/templates/vnc/server.py
anti 8dd4c78b33 refactor: strip DECNET tokens from container-visible surface
Rename the container-side logging module decnet_logging → syslog_bridge
(canonical at templates/syslog_bridge.py, synced into each template by
the deployer). Drop the stale per-template copies; setuptools find was
picking them up anyway. Swap useradd/USER/chown "decnet" for "logrelay"
so no obvious token appears in the rendered container image.

Apply the same cloaking pattern to the telnet template that SSH got:
syslog pipe moves to /run/systemd/journal/syslog-relay and the relay
is cat'd via exec -a "systemd-journal-fwd". rsyslog.d conf rename
99-decnet.conf → 50-journal-forward.conf. SSH capture script:
/var/decnet/captured → /var/lib/systemd/coredump (real systemd path),
logger tag decnet-capture → systemd-journal. Compose volume updated
to match the new in-container quarantine path.

SD element ID shifts decnet@55555 → relay@55555; synced across
collector, parser, sniffer, prober, formatter, tests, and docs so the
host-side pipeline still matches what containers emit.
2026-04-17 22:57:53 -04:00

94 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 syslog_bridge 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)
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())