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109 lines
2.3 KiB
Python
Executable file
109 lines
2.3 KiB
Python
Executable file
#! /usr/bin/env python
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# Minimal interface to the Internet telnet protocol.
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#
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# It refuses all telnet options and does not recognize any of the other
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# telnet commands, but can still be used to connect in line-by-line mode.
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# It's also useful to play with a number of other services,
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# like time, finger, smtp and even ftp.
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#
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# Usage: telnet host [port]
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#
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# The port may be a service name or a decimal port number;
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# it defaults to 'telnet'.
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import sys, posix, time
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from socket import *
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BUFSIZE = 1024
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# Telnet protocol characters
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IAC = chr(255) # Interpret as command
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DONT = chr(254)
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DO = chr(253)
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WONT = chr(252)
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WILL = chr(251)
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def main():
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host = sys.argv[1]
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try:
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hostaddr = gethostbyname(host)
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except error:
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sys.stderr.write(sys.argv[1] + ': bad host name\n')
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sys.exit(2)
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#
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if len(sys.argv) > 2:
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servname = sys.argv[2]
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else:
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servname = 'telnet'
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#
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if '0' <= servname[:1] <= '9':
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port = eval(servname)
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else:
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try:
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port = getservbyname(servname, 'tcp')
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except error:
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sys.stderr.write(servname + ': bad tcp service name\n')
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sys.exit(2)
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#
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s = socket(AF_INET, SOCK_STREAM)
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#
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try:
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s.connect(host, port)
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except error, msg:
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sys.stderr.write('connect failed: ' + `msg` + '\n')
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sys.exit(1)
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#
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pid = posix.fork()
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#
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if pid == 0:
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# child -- read stdin, write socket
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while 1:
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line = sys.stdin.readline()
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s.send(line)
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else:
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# parent -- read socket, write stdout
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iac = 0 # Interpret next char as command
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opt = '' # Interpret next char as option
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while 1:
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data = s.recv(BUFSIZE)
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if not data:
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# EOF; kill child and exit
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sys.stderr.write( '(Closed by remote host)\n')
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posix.kill(pid, 9)
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sys.exit(1)
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cleandata = ''
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for c in data:
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if opt:
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print ord(c)
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s.send(opt + c)
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opt = ''
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elif iac:
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iac = 0
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if c == IAC:
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cleandata = cleandata + c
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elif c in (DO, DONT):
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if c == DO: print '(DO)',
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else: print '(DONT)',
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opt = IAC + WONT
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elif c in (WILL, WONT):
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if c == WILL: print '(WILL)',
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else: print '(WONT)',
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opt = IAC + DONT
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else:
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print '(command)', ord(c)
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elif c == IAC:
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iac = 1
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print '(IAC)',
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else:
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cleandata = cleandata + c
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sys.stdout.write(cleandata)
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sys.stdout.flush()
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try:
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main()
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except KeyboardInterrupt:
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pass
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