In Windows 7, how to change proxy settings from command line?

Simple and working solution retrieved from http://www.ehow.com/how_6887864_do-proxy-settings-command-prompt_.html

Command to enable proxy usage:

reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings" ^
    /v ProxyEnable /t REG_DWORD /d 1 /f

Command to disable proxy usage:

reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings" ^
    /v ProxyEnable /t REG_DWORD /d 0 /f

Command to change the proxy address:

reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings" ^
    /v ProxyServer /t REG_SZ /d proxyserveraddress:proxyport /f

I have added line continuation (^) for improved readability. Also, in this case, it is more like a per-user setting than a system-wide setting.

NetSh to the rescue!

NetSh winhttp set proxy should be helpful. Here are the commands:

netsh winhttp set proxy myproxy

netsh winhttp set proxy myproxy:80 "<local>bar"

netsh winhttp set proxy proxy-server="http=myproxy;https=sproxy:88" bypass-list="*.contoso.com"

You'll need to configure a registry script that will make the changes you normally would via the Control Panel, and then merge the script to enable the proxy. You would also need an "undo" registry script to disable the changes.

In my case, I have two scripts, enable.reg and disable.reg:

Enable Proxy:

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings]
"AutoConfigURL"="http://10.10.10.1/autoproxy/proxy.pac"

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Connections]
"DefaultConnectionSettings"=hex:16,00,00,00,05,02,00,00,0d,00,00,00,0e,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00
"SavedLegacySettings"=hex:36,00,00,00,46,1a,00,00,0d,00,00,00,0e,00,00,00,32,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00

Disable Proxy:

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings]
"AutoConfigURL"=-

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Connections]
"DefaultConnectionSettings"=hex:16,00,00,00,05,02,00,00,0d,00,00,00,0e,00,00,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00
"SavedLegacySettings"=hex:36,00,00,00,46,1a,00,00,0d,00,00,00,0e,00,00,00,32,\
  00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00

In the "disable" script, the =- at the end of AutoConfigURL actually deletes the key from the registry.

Note that the values you see above are modified for the purposes of this answer. The actual hex values are much longer.

To use these scripts, I had a batch file for each one, looking something like this:

@echo off
start /min reg import C:\Path\To\Registry\File\enable_proxy.reg

That is fully workable from the command line.