New submission from sean216 <[email protected]>:
when use socket.close to close the telnet connection, in normal usage the tcp
disconnect will be (socket.close send the TCP FIN)
TCP A TCP B
1. ESTABLISHED ESTABLISHED
2. (Close)
FIN-WAIT-1 --> <SEQ=100><ACK=300><CTL=FIN,ACK> --> CLOSE-WAIT
3. FIN-WAIT-2 <-- <SEQ=300><ACK=101><CTL=ACK> <-- CLOSE-WAIT
4. (Close)
TIME-WAIT <-- <SEQ=300><ACK=101><CTL=FIN,ACK> <-- LAST-ACK
5. TIME-WAIT --> <SEQ=101><ACK=301><CTL=ACK> --> CLOSED
6. (2 MSL)
CLOSED
but sometimes socket.close will send TCP RST to disconnect the telnet and with
wrong sequence number. This kind of RST will be considering as Network RST
attack, and this packet will be dropped, the telnet connection will still
established and cannot be closed.
Seems python socket.close has some issues.
def close(self):
self._sock = _closedsocket()
dummy = self._sock._dummy
for method in _delegate_methods:
setattr(self, method, dummy)
close.__doc__ = _realsocket.close.__doc__
----------
components: Library (Lib)
files: telnet_unnormal RST.pcap
messages: 124187
nosy: sean216
priority: normal
severity: normal
status: open
title: socket.close close telnet with RST
type: behavior
versions: Python 2.5
Added file: http://bugs.python.org/file20090/telnet_unnormal RST.pcap
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