PowerShell 技能连载 - 创建快速的 Ping(第五部分)

在前一个技能中我们创建了一个名为 Test-OnlineFast 的高速的新的 PowerShell 函数,它使用 WMI 来高速 ping 任意数量的计算机。今天我们将通过向 ping 的结果增加一些列额外的属性使它变得更有用。

先让我们检查 Test-OnlineFast 是如何工作的。以下是一些例子。我们先 ping 一系列计算机。您既可以使用计算机名也可以使用 IP 地址:

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PS> Test-OnlineFast -ComputerName google.de, powershellmagazine.com, 10.10.10.200, 127.0.0.1

Address Online DNSName Status
------- ------ ------- ------
127.0.0.1 True DESKTOP-7AAMJLF Success
google.de True google.de Success
powershellmagazine.com True powershellmagazine.com Success
10.10.10.200 False Request Timed Out

我们现在 ping 整个 IP 地址段。以下例子是从我们的公共酒店 WLAN 中执行的(请将 IP 范围调整为您所在的网络):

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PS> $iprange = 1..200 | ForEach-Object { "192.168.189.$_" }

PS> Test-OnlineFast -ComputerName $iprange

Address Online DNSName Status
------- ------ ------- ------
192.168.189.200 True DESKTOP-7AAMJLF.fritz.box Success
192.168.189.1 True fritz.box Success
192.168.189.134 True PCSUP03.fritz.box Success
192.168.189.29 True fritz.repeater Success
192.168.189.64 True android-6868316cec604d25.fritz.box Success
192.168.189.142 True Galaxy-S8.fritz.box Success
192.168.189.65 True mbecker-netbook.fritz.box Success
192.168.189.30 True android-7f35f4eadd9e425e.fritz.box Success
192.168.189.10 False Request Timed Out
192.168.189.100 False Request Timed Out
192.168.189.101 False Request Timed Out
(...)

神奇的是它的超快速度。ping 整个子网只用了几秒。

现在,我们来看看这个函数。在前面的技能中我们解释了其中的一部分。这个版本向 ping 的结果增加了有用的属性,例如 OnlineDnsName,它返回关于 ping 状态的友好文本,而不是幻数。所有这些是通过计算属性的哈希表实现的,基于 ping 返回的原始信息:

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function Test-OnlineFast
{
param
(
# make parameter pipeline-aware
[Parameter(Mandatory)]
[string[]]
$ComputerName,

$TimeoutMillisec = 1000
)

# hash table with error code to text translation
$StatusCode_ReturnValue =
@{
0='Success'
11001='Buffer Too Small'
11002='Destination Net Unreachable'
11003='Destination Host Unreachable'
11004='Destination Protocol Unreachable'
11005='Destination Port Unreachable'
11006='No Resources'
11007='Bad Option'
11008='Hardware Error'
11009='Packet Too Big'
11010='Request Timed Out'
11011='Bad Request'
11012='Bad Route'
11013='TimeToLive Expired Transit'
11014='TimeToLive Expired Reassembly'
11015='Parameter Problem'
11016='Source Quench'
11017='Option Too Big'
11018='Bad Destination'
11032='Negotiating IPSEC'
11050='General Failure'
}

# hash table with calculated property that translates
# numeric return value into friendly text

$statusFriendlyText = @{
# name of column
Name = 'Status'
# code to calculate content of column
Expression = {
# take status code and use it as index into
# the hash table with friendly names
# make sure the key is of same data type (int)
$StatusCode_ReturnValue[([int]$_.StatusCode)]
}
}

# calculated property that returns $true when status -eq 0
$IsOnline = @{
Name = 'Online'
Expression = { $_.StatusCode -eq 0 }
}

# do DNS resolution when system responds to ping
$DNSName = @{
Name = 'DNSName'
Expression = { if ($_.StatusCode -eq 0) {
if ($_.Address -like '*.*.*.*')
{ [Net.DNS]::GetHostByAddress($_.Address).HostName }
else
{ [Net.DNS]::GetHostByName($_.Address).HostName }
}
}
}

# convert list of computers into a WMI query string
$query = $ComputerName -join "' or Address='"

Get-WmiObject -Class Win32_PingStatus -Filter "(Address='$query') and timeout=$TimeoutMillisec" |
Select-Object -Property Address, $IsOnline, $DNSName, $statusFriendlyText

}

本文国际来源:Creating Highspeed Ping (Part 5)

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