# Minimal interface to the Internet telnet protocol.## *** modified to use threads ***## 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, os, timefrom socket import *import thread BUFSIZE = 8*1024 # Telnet protocol characters IAC  = chr(255) # Interpret as commandDONT = chr(254)DO   = chr(253)WONT = chr(252)WILL = chr(251) def main():    if len(sys.argv) < 2:        sys.stderr.write('usage: telnet hostname [port]\n')        sys.exit(2)    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: %r\n' % (msg,))        sys.exit(1)    #    thread.start_new(child, (s,))    parent(s) def parent(s):    # read socket, write stdout    iac = 0         # Interpret next char as command    opt = ''        # Interpret next char as option    while 1:        data, dummy = s.recvfrom(BUFSIZE)        if not data:            # EOF -- exit            sys.stderr.write( '(Closed by remote host)\n')            sys.exit(1)        cleandata = ''        for c in data:            if opt:                print ord(c)##                              print '(replying: %r)' % (opt+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()##              print 'Out:', repr(cleandata) def child(s):    # read stdin, write socket    while 1:        line = sys.stdin.readline()##              print 'Got:', repr(line)        if not line: break        s.send(line) main()