Programmatic Ponderings

Configure Git for Windows to work when switching between working on-site, working off-site through a VPN, and working totally off the corporate network.

Introduction

Configuring Git to work on your corporate network can be challenging. A typical large corporate network may require Git to work behind proxy servers and firewalls, use LDAP authentication on a corporate domain, handle password expiration, deal with self-signed and internal CA certificates, and so forth. Telecommuters have the added burden of constantly switching device configurations between working on-site, working off-site through a VPN, and working totally off the corporate network at home or the local coffee shop.

There are dozens of posts on the Internet from users trying to configure Git for Windows to work on their corporate network. Many posts are oriented toward Git on Unix-based systems. Many responses only offer partial solutions without any explanation. Some responses incorrectly mix configurations for Unix-based systems with those for Windows.

Most solutions involve one of two approaches to handle proxy servers, authentication, and so forth. They are, modify Git’s .gitconfig file or set equivalent environment variables that Git will look for automatically. In my particular development situation, I spend equal amounts of time on and off a corporate network, on a Windows-based laptop. If I were always on-site, I would modify the .gitconfig file. However, since I am constantly moving on and off the network with a laptop, I chose a solution to create and destroy the environment variables, as I move on and off the corporate network.

Git for Windows

Whether you download Git from the Git website or the msysGit website, you will get the msysGit version of Git for Windows. As explained on the msysGit Wiki, msysGit is the build environment for Git for Windows. MSYS (thus the name, msysGit), is a Bourne Shell command line interpreter system, used by MinGW and originally forked from Cygwin. MinGW is a minimalist development environment for native Microsoft Windows applications.

Why do you care? By installing Git for Windows, you actually get a fairly functional Unix system running on Windows. Many of the commands you use on Unix-based systems also work on Windows, within msysGit’s Git Bash.

Setting Up Code

There are two identical versions of the post’s code, a well-commented version and a compact version.  Add either version’s contents to the .bashrc file in home directory. If you’ve worked with Linux, you are probably familiar with the .bashrc file and it’s functionality. On Unix-based systems, your home directory is ‘~/’ (/home/username), while on Windows, the equivalent directory path is ‘C:\Users\username\’.

On Windows, the .bashrc file is not created by default by Git for Windows. If you do not have a .bashrc file already, the easiest way to implement the post’s code is to download either Gist, shown below, from GitHub, rename it to .bashrc, and place it in your home directory.

After adding the code, change the PASSWORD, PROXY_SERVER, and PROXY_PORT environment variable values to match your network. Security note, this solution requires you to store you Windows user account password in plain text on your local system. This presents a certain level of security risk, as would storing it in your .gitconfig file.

The script assumes the same proxy server address for all protocols – HTTP, HTTPS, FTP, and SOCKS. If any of the proxy servers or ports are different, simply change the script’s variables.  You may also choose to add other variables and protocols, or remove them, based on your network requirements. Remember, environment variables on Windows are UPPERCASE. Even when using the interactive Git Bash shell, environment variables need to be UPPERCASED.

Lastly, as with most shells, you must exit any current interactive Git Bash shells and re-open a new interactive shell for the new functions in the .bashrc file to be available.

Verbose version:
[gist https://gist.github.com/garystafford/8128922 /]

Compact version:
[gist https://gist.github.com/garystafford/8135027 /]

Using the Code

When on-site and connected to your corporate network, or off-site and connected through a VPN, execute the ‘proxy_on’ function. When off your corporate network, execute the ‘proxy_off’ function.

Below, are a few examples of using Git to clone the popular angular.js repo from github.com (git clone https://github.com/angular/angular.js). The first example shows what happens on the corporate network when Git for Windows is not configured to work with the proxy server.

Failing to Clone GitHub Repo with Proxy Settings Off

The next example demonstrate successfully cloning the angular.js repo from github.com, while on the corporate network. The environment variables are set with the ‘proxy_on’ function. I have obscured the variable’s values and most of the verbose output from Git to hide confidential network-related details.

Successful Git Clone with Proxy Settings On

What’s My Proxy Server Address?

To setup the ‘proxy_on’ function, you need to know your proxy server’s address. One way to find this, is Control Panels -> Internet Options -> Connections -> LAN Settings. If your network requires a proxy server, it should be configured here.

LAN Settings – Proxy Server

However, on many corporate networks, Windows devices are configured to use a proxy auto-config (PAC) file. According to Wikipedia, a PAC file defines how web browsers and other user agents can automatically choose a network’s appropriate proxy server. The downside of a PAC file is that you cannot easily figure out what proxy server you are connected to.

LAN Settings – Using PAC file

To discover your proxy server with a PAC file, open a Windows command prompt and execute the following command. Use the command’s output to populate the script’s PROXY_SERVER and PORT variables.

reg query “HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings” | find /i “proxyserver”

Checking Your Proxy from the Command Prompt

Resources

Arch Linux Wiki – Proxy Settings

Tips on Git

git(1) Manual Page

Customizing Git – Git Configuration

msysGit Wiki – Git on Windows

UNIX: Set Environment Variable