Scripting VPN connections (20 Aug 2011)

Like many other companies, my company provides VPN access to its employees so that we can stay connected from our home offices or on the road. Most of the time, I connect to the company network through a web portal which downloads, installs and runs Juniper's "Network Connect" software on the Windows client system. That's all fine and dandy, except that I am a command-line guy and find it way too clumsy to fire up a web browser just in order to "dial in".

Fortunately, Juniper's Network Connect client has a command-line interface, and so here is a trivial DOS batch script which can be used to establish a connection in "I-don't-need-no-stinkin'-buttons" mode.

The script assumes that the Network Connect client has been installed and run in the usual manner (i.e. from the web portal) at least once. It will attempt to auto-detect the VPN host and user name, so in most cases all you have to specify is password information. Oh, and the script assumes you want to connect to the "SecurID(Network Connect)" realm by default, which requires entering a PIN and a number displayed on your RSA SecurID token.

@echo off
REM Launch Juniper Network Connect client from the command line
REM Written by Claus Brod in 2011, see
REM http://www.clausbrod.de/Blog/DefinePrivatePublic20110820JuniperNetworkConnect

REM --------------------------------------------------------
setlocal enableextensions

call :find_juniper_client NCCLIENTDIR
if "x%NCCLIENTDIR%"=="x" (
  echo ERROR: Cannot find Network Connect client.
  goto :end
)

rem CONFIGURE: Set your preferred VPN host here.
set url=define-your-vpn-host-here
ping -n 1 %url% >nul
if not errorlevel 1 goto :validhost

rem Try to auto-detect the VPN host from the config file
set NCCLIENTCONFIG="%NCCLIENTDIR%\..\Common Files\config.ini"
if exist %NCCLIENTCONFIG% for /f "delims=[]" %%A in ('findstr [[a-z0-9]\. %NCCLIENTCONFIG% ^| findstr /V "Network Connect"') do set url=%%A
ping -n 1 %url% >nul
if errorlevel 1 (
  echo ERROR: Host %url% does not ping. Please check your configuration.
  goto :end
)

:validhost
call :read_no_history url %url% "VPN host"

set user=guest
call :read_no_history user %user% "Username"

rem CONFIGURE: Set your preferred realm here. By default, the script
rem assumes two-stage authentication using a PIN and RSA SecurID.

set realm="SecurID(Network Connect)"
call :read_no_history realm %realm% "Realm"

REM TODO: Hide password input
set password=""
call :read_no_history password %password% "Enter PIN + token value for user %user%:"
if x%password%==x (
  echo ERROR: No password specified
  goto :end
)

cls

echo Launching Juniper Network Connect client in
echo   %NCCLIENTDIR%...
"%NCCLIENTDIR%\nclauncher.exe" -url %url% -u %user% -p %password% -r %realm%
goto :end

REM --------------------------------------------------------
:find_juniper_client
setlocal
set CLIENT=

rem search registry first
for /f "tokens=1* delims=       " %%A in ('reg query "HKLM\SOFTWARE\Juniper Networks" 2^>nul') do set LATESTVERSION="%%A"
if x%LATESTVERSION%==x"" goto :eof
for /f "tokens=2* delims=        " %%A in ('reg query %LATESTVERSION% /v InstallPath 2^>nul ^| findstr InstallPath') do set CLIENT=%%B

rem if nothing found, check filesystem
if "x%CLIENT%"=="x" for /d %%A in ("%ProgramFiles(x86)%\Juniper Networks\Network Connect*") do set CLIENT=%%A
if "x%CLIENT%"=="x" for /d %%A in ("%ProgramFiles%\Juniper Networks\Network Connect*") do set CLIENT=%%A

endlocal & set "%~1=%CLIENT%"
goto :eof


REM --------------------------------------------------------
REM read_no_history promptvar default promptmessage
:read_no_history
setlocal
set msg=%~3
if not "x%~2"=="x" (
  set msg="%~3 (default: %~2): "
)
set /P RNH_TEMP=%msg% <nul
set RNH_TEMP=

REM call external script to avoid adding to our own command history
set RNH_CMDFILE=%TEMP%\temp$$$.cmd
  (
    echo @echo off
    echo set var_=%2
    echo set /p var_=
    echo echo %%var_%%
  )> "%RNH_CMDFILE%"

for /f "delims=," %%A in ('%RNH_CMDFILE%') do set RNH_TEMP=%%A
del %RNH_CMDFILE%
endlocal & if not x%RNH_TEMP%==x set "%~1=%RNH_TEMP%"
goto :eof


REM --------------------------------------------------------
:end
endlocal

The above script is meant to be used along with the Windows version of the Network Connect client. For the Linux client, Paul D. Smith provides an excellent script and great instructions at http://mad-scientist.us/juniper.html.

See below for the direct download link for the script.

PS: The code is now available from github as well, see https://github.com/clausb/nclauncher.

PS/2: Paul D. Smith's instructions are unavailable as of November 2015; the Wayback archive still has a copy at http://web.archive.org/web/20150908095435/http://mad-scientist.us/juniper.html.

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