(PowerShell) TCP Socket through SSH Tunnel (Port Forwarding)

Demonstrates using Chilkat Socket to communicate to a TCP service through an SSH tunnel. This example will connect to an NIST time server and (using the old Time Protocol (RFC 868)), will read the current GMT time.

Note: This is not necessarily a recommended means for getting the current date/time. The most commonly used time protocol is the Network Time Protocol (RFC-1305). The intent of this example is to show how TCP communications can occur through an SSH tunnel.

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Add-Type -Path "C:\chilkat\ChilkatDotNet47-9.5.0-x64\ChilkatDotNet47.dll"

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

$tunnel = New-Object Chilkat.Socket

$sshHostname = "sftp.example.com"
$sshPort = 22

# Connect to an SSH server and establish the SSH tunnel:
$success = $tunnel.SshOpenTunnel($sshHostname,$sshPort)
if ($success -ne $true) {
    $($tunnel.LastErrorText)
    exit
}

# Authenticate with the SSH server via a login/password
# or with a public key.
# This example demonstrates SSH password authentication.
$success = $tunnel.SshAuthenticatePw("mySshLogin","mySshPassword")
if ($success -ne $true) {
    $($tunnel.LastErrorText)
    exit
}

# OK, the SSH tunnel is setup.  Now open a channel within the tunnel.
# Once the channel is obtained, the Socket API may
# be used exactly the same as usual, except all communications
# are sent through the channel in the SSH tunnel.
# Any number of channels may be created from the same SSH tunnel.
# Multiple channels may coexist at the same time.

# Connect to an NIST time server and read the current date/time

$maxWaitMs = 4000
$useTls = $false
$channel = $tunnel.SshOpenChannel("time-c.nist.gov",37,$useTls,$maxWaitMs)
if ($tunnel.LastMethodSuccess -eq $false) {
    $($tunnel.LastErrorText)
    exit
}

# The time server will send a big-endian 32-bit integer representing
# the number of seconds since since 00:00 (midnight) 1 January 1900 GMT.
# The ReceiveInt32 method will receive a 4-byte integer, but returns
# $true or $false to indicate success.  If successful, the integer
# is obtained via the ReceivedInt property.
$bigEndian = $true
$success = $channel.ReceiveInt32($bigEndian)
if ($success -ne $true) {
    $($channel.LastErrorText)

    exit
}

$dt = New-Object Chilkat.CkDateTime
$dt.SetFromNtpTime($channel.ReceivedInt)

# Show the current local date/time
$bLocalTime = $true
$("Current local date/time: " + $dt.GetAsRfc822($bLocalTime))

# Close the SSH channel.
$success = $channel.Close($maxWaitMs)
if ($success -ne $true) {
    $($channel.LastErrorText)

    exit
}

# It is possible to create a new channel from the existing SSH tunnel for the next connection:
# Any number of channels may be created from the same SSH tunnel.
# Multiple channels may coexist at the same time.
$channel = $tunnel.SshOpenChannel("time-a.nist.gov",37,$useTls,$maxWaitMs)
if ($tunnel.LastMethodSuccess -eq $false) {
    $($tunnel.LastErrorText)
    exit
}

# Review the LastErrorText to see that the connection was made via the SSH tunnel:
$($tunnel.LastErrorText)

# Close the connection to time-a.nist.gov.  This is actually closing our channel
# within the SSH tunnel, but keeps the tunnel open for the next port-forwarded connection.
$success = $channel.Close($maxWaitMs)
if ($success -ne $true) {
    $($channel.LastErrorText)

    exit
}

# Finally, close the SSH tunnel.
$success = $tunnel.SshCloseTunnel()
if ($success -ne $true) {
    $($tunnel.LastErrorText)
    exit
}

$("TCP SSH tunneling example completed.")