git - SSL certificate rejected trying to access GitHub over HTTPS behind firewall

Question

I'm stuck behind a firewall so have to use HTTPS to access my GitHub repository. I'm using cygwin 1.7.7 on Windows XP.

I've tried setting the remote to https://[email protected]/username/ExcelANT.git, but pushing prompts for a password, but doesn't do anything once I've entered it. https://username:<password>github.com/username/ExcelANT.git and cloning the empty repo from scratch but each time it gives me the same error

error: SSL certificate problem, verify that the CA cert is OK. Details:
error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed while accessing https://github.com/username/ExcelANT.git/info/refs

Turning on GIT_CURL_VERBOSE=1 gives me

* About to connect() to github.com port 443 (#0)
* Trying 207.97.227.239... * successfully set certificate verify locations:
* CAfile: none
CApath: /usr/ssl/certs
* SSL certificate problem, verify that the CA cert is OK. Details:
error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed
* Expire cleared
* Closing connection #0
* About to connect() to github.com port 443 (#0)
* Trying 207.97.227.239... * successfully set certificate verify locations:
* CAfile: none
CApath: /usr/ssl/certs
* SSL certificate problem, verify that the CA cert is OK. Details:
error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed
* Expire cleared
* Closing connection #0
error: SSL certificate problem, verify that the CA cert is OK. Details:
error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed while accessing https://github.com/username/ExcelANT.git/info/refs

fatal: HTTP request failed

Is this a problem with my firewall, cygwin or what?

I hadn't set the HTTP proxy in the Git config, however it's an ISA server that needs NTLM authentication, not basic, so unless anyone knows how to force git to use NTLM, I'm scuppered.

Answer 1

The problem is that you do not have any of Certification Authority certificates installed on your system. And these certs cannot be installed with cygwin's setup.exe.

Update: Install Net/ca-certificates package in cygwin (thanks dirkjot)

There are two solutions:

1. Actually install root certificates. Curl guys extracted for you certificates from Mozilla.

   cacert.pem file is what you are looking for. This file contains > 250 CA certs (don't know how to trust this number of ppl). You need to download this file, split it to individual certificates put them to /usr/ssl/certs (your CApath) and index them.

   Here is how to do it. With cygwin setup.exe install curl and openssl packages execute:

   $ cd /usr/ssl/certs
   $ curl http://curl.haxx.se/ca/cacert.pem |
     awk '{print > "cert" (1+n) ".pem"} /-----END CERTIFICATE-----/ {n++}'
   $ c_rehash
   

   Important: In order to use c_rehash you have to install openssl-perl too.

2. Ignore SSL certificate verification.

   WARNING: Disabling SSL certificate verification has security implications. Without verification of the authenticity of SSL/HTTPS connections, a malicious attacker can impersonate a trusted endpoint (such as GitHub or some other remote Git host), and you'll be vulnerable to a Man-in-the-Middle Attack. Be sure you fully understand the security issues and your threat model before using this as a solution.

   $ env GIT_SSL_NO_VERIFY=true git clone https://github...