1# Minimal interface to the Internet telnet protocol. 2# 3# *** modified to use threads *** 4# 5# It refuses all telnet options and does not recognize any of the other 6# telnet commands, but can still be used to connect in line-by-line mode. 7# It's also useful to play with a number of other services, 8# like time, finger, smtp and even ftp. 9# 10# Usage: telnet host [port] 11# 12# The port may be a service name or a decimal port number; 13# it defaults to 'telnet'. 14 15 16import sys, os, time 17from socket import * 18import thread 19 20BUFSIZE = 8*1024 21 22# Telnet protocol characters 23 24IAC = chr(255) # Interpret as command 25DONT = chr(254) 26DO = chr(253) 27WONT = chr(252) 28WILL = chr(251) 29 30def main(): 31 if len(sys.argv) < 2: 32 sys.stderr.write('usage: telnet hostname [port]\n') 33 sys.exit(2) 34 host = sys.argv[1] 35 try: 36 hostaddr = gethostbyname(host) 37 except error: 38 sys.stderr.write(sys.argv[1] + ': bad host name\n') 39 sys.exit(2) 40 # 41 if len(sys.argv) > 2: 42 servname = sys.argv[2] 43 else: 44 servname = 'telnet' 45 # 46 if '0' <= servname[:1] <= '9': 47 port = eval(servname) 48 else: 49 try: 50 port = getservbyname(servname, 'tcp') 51 except error: 52 sys.stderr.write(servname + ': bad tcp service name\n') 53 sys.exit(2) 54 # 55 s = socket(AF_INET, SOCK_STREAM) 56 # 57 try: 58 s.connect((host, port)) 59 except error, msg: 60 sys.stderr.write('connect failed: %r\n' % (msg,)) 61 sys.exit(1) 62 # 63 thread.start_new(child, (s,)) 64 parent(s) 65 66def parent(s): 67 # read socket, write stdout 68 iac = 0 # Interpret next char as command 69 opt = '' # Interpret next char as option 70 while 1: 71 data, dummy = s.recvfrom(BUFSIZE) 72 if not data: 73 # EOF -- exit 74 sys.stderr.write( '(Closed by remote host)\n') 75 sys.exit(1) 76 cleandata = '' 77 for c in data: 78 if opt: 79 print ord(c) 80## print '(replying: %r)' % (opt+c,) 81 s.send(opt + c) 82 opt = '' 83 elif iac: 84 iac = 0 85 if c == IAC: 86 cleandata = cleandata + c 87 elif c in (DO, DONT): 88 if c == DO: print '(DO)', 89 else: print '(DONT)', 90 opt = IAC + WONT 91 elif c in (WILL, WONT): 92 if c == WILL: print '(WILL)', 93 else: print '(WONT)', 94 opt = IAC + DONT 95 else: 96 print '(command)', ord(c) 97 elif c == IAC: 98 iac = 1 99 print '(IAC)', 100 else: 101 cleandata = cleandata + c 102 sys.stdout.write(cleandata) 103 sys.stdout.flush() 104## print 'Out:', repr(cleandata) 105 106def child(s): 107 # read stdin, write socket 108 while 1: 109 line = sys.stdin.readline() 110## print 'Got:', repr(line) 111 if not line: break 112 s.send(line) 113 114main() 115