Every three months, security compliance requires to change the password. This also applies for the proxy authentication. If you have a bunch of tools, like Eclipse, IntelliJ or any other applications that needs proxy auth for updates and access, it can be a hassle to change the settings in all applications. For Windows, cntlm is a relief. It stands between your applications and the corporate proxy, adding NTLM authentication on-the-fly. So basically you change the auth data only for cntlm, and all other applications using it to bypass the proxy.