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