在Python中使用Telnet

要在Python中使用Telnet，我们可以使用telnetlib模块。该模块提供实现Telnet协议的Telnet类。
Telnet模块有几个基础方法，在本示例中，我们将依次介绍这些函数：read_until， read_all()和 write()

Python中的Telnet脚本

一个简单的telnet脚本例程：

import getpass
import sys
import telnetlib

HOST = "hostname"

user = raw_input("Enter your remote account: ")

password = getpass.getpass()

tn = telnetlib.Telnet(HOST)

tn.read_until("login: ")

tn.write(user + "
")

if password:
    tn.read_until("Password: ")
    tn.write(password + "
")

tn.write("ls
")

tn.write("exit
")

print tn.read_all()

更完备的telnet脚本例程：

在ActiveState上，可以找到telnetlib的更多Python脚本，例如以下脚本。有关在Python中使用Telnet客户端的更多信息，请参见官方文件。

在以下例程中，使用Python的标准telnetlib模块将命令发送到一个或多个登录名。

# auto_telnet.py - remote control via telnet
import os, sys, string, telnetlib
from getpass import getpass

class AutoTelnet:
    def __init__(self, user_list, cmd_list, **kw):
        self.host = kw.get('host', 'localhost')
        self.timeout = kw.get('timeout', 600)
        self.command_prompt = kw.get('command_prompt', "$ ")
        self.passwd = {}
        for user in user_list:
            self.passwd[user] = getpass("Enter user '%s' password: " % user)
        self.telnet = telnetlib.Telnet()
        for user in user_list:
            self.telnet.open(self.host)
            ok = self.action(user, cmd_list)
            if not ok:
                print "Unable to process:", user
            self.telnet.close()

    def action(self, user, cmd_list):
        t = self.telnet
        t.write("\n")
        login_prompt = "login: "
        response = t.read_until(login_prompt, 5)
        if string.count(response, login_prompt):
            print response
        else:
            return 0
        password_prompt = "Password:"
        t.write("%s\n" % user)
        response = t.read_until(password_prompt, 3)
        if string.count(response, password_prompt):
            print response
        else:
            return 0
        t.write("%s\n" % self.passwd[user])
        response = t.read_until(self.command_prompt, 5)
        if not string.count(response, self.command_prompt):
            return 0
        for cmd in cmd_list:
            t.write("%s\n" % cmd)
            response = t.read_until(self.command_prompt, self.timeout)
            if not string.count(response, self.command_prompt):
                return 0
            print response
        return 1

if __name__ == '__main__':
    basename = os.path.splitext(os.path.basename(sys.argv[0]))[0]
    logname = os.environ.get("LOGNAME", os.environ.get("USERNAME"))
    host = 'localhost'
    import getopt
    optlist, user_list = getopt.getopt(sys.argv[1:], 'c:f:h:')
    usage = """
usage: %s [-h host] [-f cmdfile] [-c "command"] user1 user2 ...
    -c  command
    -f  command file
    -h  host  (default: '%s')

Example:  %s -c "echo $HOME" %s
""" % (basename, host, basename, logname)
    if len(sys.argv) < 2:
        print usage
        sys.exit(1)
    cmd_list = []
    for (opt, optarg) in optlist:
        if opt == '-f':
            for r in open(optarg).readlines():
                if string.rstrip(r):
                    cmd_list.append(r)
        elif opt == '-c':
            command = optarg
            if command[0] == '"' and command[-1] == '"':
                command = command[1:-1]
            cmd_list.append(command)
        elif opt == '-h':
            host = optarg
    autoTelnet = AutoTelnet(user_list, cmd_list, host=host)