如果未安装Telnet来检查端口是否打开并且可访问，人们会使用什么？例如telnet <destination>，即使telnet无法与另一端的系统进行交互，我也曾经使用过并且知道它的技术。

由于没有安装Windows 2008 telnet，所以我有点迷路了。那我该怎么用呢。还有一些东西，如果它在Linux或Solaris中不存在的话。

我是在不同网站上工作的顾问。由于多种原因（访问权限，更改控制时间，如果我明年安装它而有人使用它会给我们带来一些责任等），所以无法在其他人的服务器上安装。但是，USB或其他自包含的未安装工具将是很棒的...

像老板一样使用Powershell

基本代码

$ipaddress = "4.2.2.1"
$port = 53
$connection = New-Object System.Net.Sockets.TcpClient($ipaddress, $port)

if ($connection.Connected) {
    Write-Host "Success"
}
else {
    Write-Host "Failed"
}

将其转换为cmdlet

[CmdletBinding()]
Param(
  [Parameter(Mandatory=$True,Position=1)]
   [string]$ip,

   [Parameter(Mandatory=$True,Position=2)]
   [int]$port
)

$connection = New-Object System.Net.Sockets.TcpClient($ip, $port)
if ($connection.Connected) {
    Return "Connection Success"
}
else {
    Return "Connection Failed"
}

另存为脚本并一直使用

然后，您可以在powershell或cmd提示符中使用以下命令：

PS C:\> telnet.ps1 -ip 8.8.8.8 -port 53

要么

PS C:\> telnet.ps1 8.8.8.8 53

这是在没有telnet的情况下测试TCP端口的几种不同方法。

BASH（手册页）

# cat < /dev/tcp/127.0.0.1/22
SSH-2.0-OpenSSH_5.3
^C

# cat < /dev/tcp/127.0.0.1/23
bash: connect: Connection refused
bash: /dev/tcp/127.0.0.1/23: Connection refused

卷曲

# curl -v telnet://127.0.0.1:22
* About to connect() to 127.0.0.1 port 22 (#0)
*   Trying 127.0.0.1... connected
* Connected to 127.0.0.1 (127.0.0.1) port 22 (#0)
SSH-2.0-OpenSSH_5.3
^C

# curl -v telnet://127.0.0.1:23
* About to connect() to 127.0.0.1 port 23 (#0)
*   Trying 127.0.0.1... Connection refused
* couldn't connect to host
* Closing connection #0
curl: (7) couldn't connect to host

蟒蛇

# python
Python 2.6.6 (r266:84292, Oct 12 2012, 14:23:48)
[GCC 4.4.6 20120305 (Red Hat 4.4.6-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import socket
>>> clientsocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
>>> clientsocket.connect(('127.0.0.1', 22))
>>> clientsocket.send('\n')
1
>>> clientsocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
>>> clientsocket.connect(('127.0.0.1', 23))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 1, in connect
socket.error: [Errno 111] Connection refused

佩尔

# perl
use IO::Socket::INET;
$| = 1;
my $socket = new IO::Socket::INET(
  PeerHost => '127.0.0.1',
  PeerPort => '22',
  Proto => 'tcp',
);
die "cannot connect to the server $!\n" unless $socket;
print "connected to the server\n";
^D
connected to the server