Alpaca is a local HTTP proxy for command-line tools. It supports proxy auto-configuration (PAC) files and NTLM authentication.

If you're using macOS and use Homebrew, you can install using:

$ brew tap samuong/alpaca
$ brew install samuong/alpaca/alpaca

Launch Alpaca by running alpaca, or by using brew services start alpaca.

If you've got the Go tool installed, you can install using:

$ go get -v -u github.com/samuong/alpaca

Alpaca can be downloaded from the GitHub releases page.

Start Alpaca by running the alpaca binary.

On macOS and GNOME systems, Alpaca uses the PAC URL from your system settings. If you'd like to override this, or if Alpaca fails to detect your settings, you can set this manually using the -C flag.

If you use NoMAD and have configured it to use the keychain, Alpaca will use these credentials to authenticate to any NTLM challenge from your proxies. You can also supply your domain and username (via command-line flags) and a password (via a prompt):

$ alpaca -d MYDOMAIN -u me
Password (for MYDOMAIN\me):

You also need to configure your tools to send requests via Alpaca. Usually this will require setting the http_proxy and https_proxy environment variables:

$ export http_proxy=http://localhost:3128
$ export https_proxy=http://localhost:3128
$ curl -s https://raw.githubusercontent.com/samuong/alpaca/master/README.md
# Alpaca
...

When moving from, say, a corporate network to a public WiFi network (or vice-versa), the proxies listed in the PAC script might become unreachable. When this happens, Alpaca will temporarily bypass the parent proxy and send requests directly, so there's no need to manually unset/re-set http_proxy and https_proxy as you move between networks.