commit c70f53bed32af4060d3bd193aef619703b688c93
Author: chuzhongzai <chuzhongzai@hotmail.com>
Date:   Thu Dec 19 00:14:14 2024 +0800

    first commit

diff --git a/GateWay-KeepAlive.ps1 b/GateWay-KeepAlive.ps1
new file mode 100644
index 0000000..d29df9b
--- /dev/null
+++ b/GateWay-KeepAlive.ps1
@@ -0,0 +1,172 @@
+. $(-Join($(pwd).Path, '\config.ps1'))
+. $(-Join($(pwd).Path, '\proxy-test.ps1'))
+
+function isDhcpEnable(){
+    return Get-NetIPConfiguration | select-object InterfaceAlias, IPv4Address, @{n="dhcp";e={$_.NetIPv4Interface.DHCP}} | Select-Object -ExpandProperty dhcp
+}
+
+function isForeignConnected {
+    # check foreign network availability
+    $result = Test-NetConnection -ComputerName $Global:TestDomain -Port 443
+
+    if ($result.TcpTestSucceeded) {
+        Write-Host "Successfully connected to $($Global:TestDomain) via HTTPS. isCustomGateway:$($Global:isCustomGateway)"
+        return $true
+    } else {
+        Write-Host "Failed to connect to $($Global:TestDomain) via HTTPS. isCustomGateway:$($Global:isCustomGateway)"
+        return $false
+    }  
+}
+
+function isNetworkConnected {
+    # check network availability
+    $result = $(Test-Connection -ComputerName $Global:TestIP -Count 1).Status -eq 'Success'
+    if ($result) {
+        Write-Host "Successfully connected to $($Global:TestIP) via ICMP. isCustomGateway:$($Global:isCustomGateway)"
+        return $true
+    } else {
+        Write-Host "Failed to connect to $($Global:TestIP) via ICMP. isCustomGateway:$($Global:isCustomGateway)"
+        return $false
+    }  
+}
+
+function setDhcp($enable){
+    if($enable){
+        Set-NetIPInterface -InterfaceAlias $Global:TargetNetworkAdapter.name -Dhcp Enabled
+        Write-Host enable dhcp
+    } else {
+        Set-NetIPInterface -InterfaceAlias $Global:TargetNetworkAdapter.name -Dhcp Disabled
+        Write-Host disable dhcp
+    }
+}
+
+function changeGateway{
+    param(
+        $adapter,$isCustomGateway
+    )
+    Write-Host "Changing gateway for adapter: $($adapter.Name) isCustomGateway $($isCustomGateway)"
+    
+  
+    # check gateway availability
+    if($isCustomGateway){
+        $currentGateway = $(Get-NetIPConfiguration).IPv4DefaultGateway.NextHop
+        if($currentGateway -eq $Global:TargetGateway){
+            Write-Host "current gateway is $currentGateway same as targetGateway $Global:TargetGateway, change gateway canceled"
+            $Global:isCustomGateway = $true
+            return
+        }
+        $result = $(Test-Connection $Global:TargetGateway -Count 1).Status
+        if (! ($result -eq 'Success')){
+            Write-Host custom gateway $Global:TargetGateway is $result, refuse to change
+            return
+        }
+    }
+
+    # check current ip configuration
+    $existingIP = Get-NetIPAddress -InterfaceAlias $adapter.Name -AddressFamily IPv4
+
+    # if have ip configuration, delete it
+    if ($existingIP) {
+        Write-Host "Removing existing IP address: $($existingIP.IPAddress)"
+        Remove-NetIPAddress -InterfaceAlias $adapter.Name -Confirm:$false
+    }
+
+    # delete current route(gateway)
+    $existingRoute = Get-NetRoute -InterfaceAlias $adapter.Name -DestinationPrefix "0.0.0.0/0"
+    if ($existingRoute) {
+        Write-Host "Removing existing default route..."
+        Remove-NetRoute -InterfaceAlias $adapter.Name  -Confirm:$false
+    }
+
+    if ($isCustomGateway){ #setting gateway
+
+        # config customGateway
+        $Global:isCustomGateway = $true
+
+        # setting dns server
+        Set-DnsClientServerAddress -InterfaceAlias $adapter.name -ServerAddresses ($Global:TargetGateway, $Global:TargetGateway)
+        # disable dhcp
+        setDhcp($false)
+        # setting gateway to customGateway
+        New-NetIPAddress -InterfaceAlias $adapter.Name -AddressFamily IPv4 -IPAddress $Global:TargetIP -PrefixLength 24 -DefaultGateway $Global:TargetGateway
+    } else {
+        # config originalGateway
+        $Global:isCustomGateway = $false
+
+        # setting dns server
+        Set-DnsClientServerAddress -InterfaceAlias $adapter.name -ServerAddresses ($Global:originalDns, $Global:originalDns)
+
+        # setting gateway to originalGateway
+        New-NetIPAddress -InterfaceAlias $adapter.Name -AddressFamily IPv4 -IPAddress $Global:TargetIP -PrefixLength 24 -DefaultGateway $Global:originalGateway
+    }
+    Start-Sleep 3
+}
+
+
+function getIPAddress(){
+    $IP = Get-NetIPConfiguration | Select-Object -ExpandProperty IPV4Address | Select-Object -ExpandProperty IPAddress
+    return $IP
+}
+
+function getNetworkAdapter(){
+    $networkAdapters = Get-NetAdapter | ForEach-Object {
+        [PSCustomObject]@{
+            Name       = $_.Name
+            Interface  = $_.InterfaceDescription
+            Status     = $_.Status
+            LinkSpeed  = $_.LinkSpeed
+            MacAddress = $_.MacAddress
+        }
+    }
+    
+    foreach ($networkAdapter in $networkAdapters){
+        if($networkAdapter.name.Contains($TargetNetworkAdapterKeyword)){
+            $Global:TargetNetworkAdapter = $networkAdapter
+            break;
+        }
+    }
+    Write-Host "getNetworkAdapter: " $Global:TargetNetworkAdapter
+}
+
+function init {
+    # check permission
+    $IsAdmin = [Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()
+    if (-not $IsAdmin.IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator)) {
+        # if not admin permission, restart it with admin permission
+        Write-Host "Requesting Administrator privileges..."
+        Start-Process pwsh -ArgumentList "-NoExit", "-File", $PSCommandPath -Verb RunAs
+        exit
+    }
+
+    Write-Host "Running with Administrator privileges!"
+
+    # get netAdapter instance
+    getNetworkAdapter
+
+    Write-Host "current adapter: $($Global:TargetNetworkAdapter.name)"
+
+    # try to change to customGateway at start
+    changeGateway $Global:TargetNetworkAdapter $true
+}
+
+function loop(){
+    while($true){
+        # if network offline and using customGateway, try to restore to originalGateway
+        if((!$(isNetworkConnected)) -and $Global:isCustomGateway){
+            changeGateway $Global:TargetNetworkAdapter $false
+        } 
+
+        # if customGateway proxy is working and using original gateway, try to change to customGateway
+        if($(Test-SocksProxy -ProxyHost $Global:TargetGateway -ProxyPort 1070) -and (!$Global:isCustomGateway)){
+            Write-Host isCustomGateway $Global:isCustomGateway
+            changeGateway $Global:TargetNetworkAdapter $true
+        }
+
+        # if customGateway proxy is not working but network still online, do nothing
+
+        Start-Sleep 1
+    }
+}
+
+init
+loop
diff --git a/config.ps1 b/config.ps1
new file mode 100644
index 0000000..e6eb86a
--- /dev/null
+++ b/config.ps1
@@ -0,0 +1,9 @@
+$Global:TestDomain = "www.google.com"               #测试代理是否可用
+$Global:TestIP = "223.5.5.5"                        #测试是否连接网络
+$Global:originalDns = "223.5.5.5"                   #默认DNS
+$Global:TargetGateway = "192.168.6.2"               #代理网关
+$Global:TargetIP = "192.168.6.4"                    #默认ip
+$Global:originalGateway = "192.168.6.1"             #默认网关
+$Global:TargetNetworkAdapter = {}                   #网络适配器实例
+$Global:TargetNetworkAdapterKeyword = "Ethernet"    #网络适配器名字通配符
+$Global:isCustomGateway = $false                    #是否为自定义网关
\ No newline at end of file
diff --git a/proxy-test.ps1 b/proxy-test.ps1
new file mode 100644
index 0000000..b55e8d9
--- /dev/null
+++ b/proxy-test.ps1
@@ -0,0 +1,76 @@
+function Test-SocksProxy {
+    param (
+        [string]$ProxyHost,
+        [int]$ProxyPort,
+        [string]$TestHost = "google.com",
+        [int]$TestPort = 443
+    )
+
+    $result = $false
+    try {
+        # check if proxy is working
+        $result = $(Test-Connection $ProxyHost -Count 1).Status
+        if(!($result -eq "Success")){
+            Write-Host proxy host $ProxyHost is $result
+            return $false
+        }
+
+        # create TCP client
+        $tcpClient = New-Object System.Net.Sockets.TcpClient
+        $tcpClient.SendTimeout = 1000
+        $tcpClient.ReceiveTimeout = 1000
+        $tcpClient.Connect($ProxyHost, $ProxyPort)
+
+        # 代理成功连接，开始验证目标地址是否可达
+        $stream = $tcpClient.GetStream()
+
+        # 构建 SOCKS5 握手包 (Initial request)
+        $handshake = [byte[]](0x05, 0x01, 0x00)  # Version 5, 1 method, No auth
+        $stream.Write($handshake, 0, $handshake.Length)
+
+        # 接收服务器响应
+        $response = New-Object byte[] 2
+        $stream.Read($response, 0, $response.Length)
+
+        if ($response[1] -ne 0x00) {
+            throw "SOCKS handshake failed. Proxy does not support no-authentication."
+        }
+
+        # 将 TestHost 转换为字节数组
+        $hostBytes = [System.Text.Encoding]::ASCII.GetBytes($TestHost)
+
+        # 构建 SOCKS5 连接请求
+        $connectRequest = @(
+            0x05, 0x01, 0x00, 0x03,   # Version 5, Connect, Reserved, Domain
+            [byte]$hostBytes.Length   # Domain length
+        ) + $hostBytes + @(
+            [byte]($TestPort -shr 8), # Port (high byte)
+            [byte]($TestPort -band 0xFF) # Port (low byte)
+        )
+
+        $stream.Write($connectRequest, 0, $connectRequest.Length)
+
+        # 接收连接响应
+        $connectResponse = New-Object byte[] 10
+        $stream.Read($connectResponse, 0, $connectResponse.Length)
+
+        if ($connectResponse[1] -eq 0x00) {
+            Write-Host "Proxy is valid and can connect to ${TestHost}:$TestPort."
+            $result = $true
+        } else {
+            throw "SOCKS connection to ${TestHost}:$TestPort failed. Response code: $($connectResponse[1])"
+            $result = $false
+        }
+    } catch {
+        Write-Host "Proxy test failed: $_"
+        $result = $false
+    } finally {
+        # 关闭连接
+        if ($stream) { $stream.Dispose() }
+        if ($tcpClient) { $tcpClient.Close() }
+    }
+    return $result
+}
+
+
+# Test-SocksProxy -ProxyHost "192.168.6.2" -ProxyPort 1081