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Automating JNLP Downloads with PowerShell Using Session Cookies

Automate authenticated JNLP downloads in PowerShell using a WebRequestSession, manual cookie handling, URL-encoding, and Invoke-WebRequest with browser headers.

Stephen NdegwaPublished Last updated 2 min read
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When managing remote servers or BMC interfaces, some resources such as JNLP (Java Network Launch Protocol) files require authentication via cookies and session handling. Manually downloading these files can be cumbersome. PowerShell provides a way to automate this process using web sessions and cookie management.

Creating a Persistent Web Session

A web session in PowerShell allows you to persist cookies, headers, and other session parameters across multiple requests. This is essential when working with authenticated resources. To create a session and set a custom user agent, use:

$session = New-Object Microsoft.PowerShell.Commands.WebRequestSession
$session.UserAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Safari/537.36"

Adding Required Cookies

Many interfaces require specific cookies for authentication. In PowerShell, you can add cookies to the session like this:

$session.Cookies.Add((New-Object System.Net.Cookie("test", "1", "/", "10.10.10.4")))
$session.Cookies.Add((New-Object System.Net.Cookie("SessionCookie", "V3rBznVdGPy1MDotq4DBUoMiYfbEnEq9000", "/", "10.10.10.4")))
$session.Cookies.Add((New-Object System.Net.Cookie("BMC_IP_ADDR", "10.10.10.4", "/", "10.10.10.4")))
$session.Cookies.Add((New-Object System.Net.Cookie("SessionExpired", "false", "/", "10.10.10.4")))
$session.Cookies.Add((New-Object System.Net.Cookie("Username", "admin", "/", "10.10.10.4")))
$session.Cookies.Add((New-Object System.Net.Cookie("PNO", "4", "/", "10.10.10.4")))
$session.Cookies.Add((New-Object System.Net.Cookie("gMultiLAN", "true", "/", "10.10.10.4")))

Some cookies, like settings, may contain special characters ({}, [], ,) that are not allowed directly. You must URL-encode them:

$settingsValue = "{eth:[0,1],ethstr:['eth0','eth1'],lan:[1,8],enable:[1,1],flag:[1,1]}"
$encodedValue = [System.Net.WebUtility]::UrlEncode($settingsValue)
$session.Cookies.Add((New-Object System.Net.Cookie("settings", $encodedValue, "/", "10.10.10.4")))

Downloading the JNLP File

Once the session and cookies are configured, you can download the JNLP file using Invoke-WebRequest. Include headers like Referer and Accept to mimic a browser request:

Invoke-WebRequest `
  -Uri "http://10.10.10.4/Java/jviewer.jnlp?EXTRNIP=10.10.10.4&JNLPSTR=JViewer" `
  -WebSession $session `
  -Headers @{
      "Accept" = "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7"
      "Accept-Language" = "en-US,en;q=0.9,sw;q=0.8"
      "Accept-Encoding" = "gzip, deflate"
      "Referer" = "http://10.10.10.4/page/jviewer_launch_new.html?JNLPSTR=JViewer&JNLPNAME=/Java/jviewer.jnlp"
      "Upgrade-Insecure-Requests" = "1"
  } `
  -OutFile "jviewer.jnlp" `
  -UseBasicParsing

This will save the jviewer.jnlp file to your current directory, ready for launching with Java Web Start.

Benefits of Using PowerShell Sessions

  • Persistent Authentication: Cookies and session information persist across requests.
  • Automation: Scripted downloads remove the need for manual browser interaction.
  • Custom Headers: Easily set headers to mimic real browser behavior.
  • Compatibility: Works across PowerShell 5.1 and PowerShell Core (7+).

Full Working Script

Here is the complete script in one block, ready to run:

# Create and configure a persistent web session
$session = New-Object Microsoft.PowerShell.Commands.WebRequestSession
$session.UserAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Safari/537.36"

# Add required cookies
$session.Cookies.Add((New-Object System.Net.Cookie("test", "1", "/", "10.10.10.4")))
$session.Cookies.Add((New-Object System.Net.Cookie("SessionCookie", "V3rBznVdGPy1MDotq4DBUoMiYfbEnEq9000", "/", "10.10.10.4")))
$session.Cookies.Add((New-Object System.Net.Cookie("BMC_IP_ADDR", "10.10.10.4", "/", "10.10.10.4")))
$session.Cookies.Add((New-Object System.Net.Cookie("SessionExpired", "false", "/", "10.10.10.4")))
$session.Cookies.Add((New-Object System.Net.Cookie("Username", "admin", "/", "10.10.10.4")))
$session.Cookies.Add((New-Object System.Net.Cookie("PNO", "4", "/", "10.10.10.4")))
$session.Cookies.Add((New-Object System.Net.Cookie("gMultiLAN", "true", "/", "10.10.10.4")))

# URL-encode the complex settings cookie value
$settingsValue = "{eth:[0,1],ethstr:['eth0','eth1'],lan:[1,8],enable:[1,1],flag:[1,1]}"
$encodedValue = [System.Net.WebUtility]::UrlEncode($settingsValue)
$session.Cookies.Add((New-Object System.Net.Cookie("settings", $encodedValue, "/", "10.10.10.4")))

# Download JNLP using the authenticated session
Invoke-WebRequest `
  -Uri "http://10.10.10.4/Java/jviewer.jnlp?EXTRNIP=10.10.10.4&JNLPSTR=JViewer" `
  -WebSession $session `
  -Headers @{
      "Accept" = "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7"
      "Accept-Language" = "en-US,en;q=0.9,sw;q=0.8"
      "Accept-Encoding" = "gzip, deflate"
      "Referer" = "http://10.10.10.4/page/jviewer_launch_new.html?JNLPSTR=JViewer&JNLPNAME=/Java/jviewer.jnlp"
      "Upgrade-Insecure-Requests" = "1"
  } `
  -OutFile "jviewer.jnlp" `
  -UseBasicParsing

This script ensures all session cookies are set correctly, handles complex cookie values safely, and automates the download of the JNLP file.

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