This tuturial will explain how to use git through a proxy, for example if you are behind a firewall or on a private network.
The examples are valid for connections inside the .cms network at Point 5, but it should be simple to adapt them to other configurations.
The most common are an HTTP proxy, and a SOCKS5 proxy - for example, one opened with the ssh -D command, documented in ssh(1).
The ssh command distributed with most Unix-like systems can open a SOCKS proxy on the local machine and forward all connections through the ssh tunnel.
For example
ssh -f -N -D 1080 cmsusr.cms
will connect to the host cmsusr.cms, open a SOCKS proxy on the local host on
port 1080 (-D 1080), and put the process in background after a successful
connection (-f -N).
If the remote has a format like
git@github.com:cms-sw/cmssw.git
ssh://git@github.com/cms-sw/cmssw.git
then you are connecting to the git server using the SSH protocol.
In this case, git relis on ssh to handle the connection; in order to connect
through a SOCKS proxy you have to configure ssh itself, setting the ProxyCommand
option in your ~/.ssh/config file:
Host github.com
User git
ProxyCommand nc -x localhost:1080 %h %p
OR On CentOS7 you can
Host github.com
User git
ProxyCommand ssh cmsusr nc %h %p
For more information, see ssh_config(5).
If the remote has a format like
http://github.com/cms-sw/cmssw.git
https://github.com/cms-sw/cmssw.git
then you are connecting to the git server using the HTTP or HTTPS protocols. In the old days, this used to be a dumb protocol, but since git 1.6.6 it uses a smart protocol similar to that used by SSH or GIT.
In this case git uses libcurl to handle the connection; the version of git bundled
with CMSSW supports different kinds of proxies: SOCKS4, SOCKS4a, SOCKS5, and HTTP/HTTPS.
In order to connect through any proxy supported by libcurl, you can set the http.proxy
option:
git config --global http.proxy socks5://localhost:1080
For more information, see the --proxy option in curl(1)
and the http.proxy entry in git-config(1).
If the remote has a format like
git://github.com/cms-sw/cmssw.git
then you are connecting to the git server using the GIT protocol.
In this case, it is possible to use a helper command to connect through any kind of proxy.
A simple script is included with CMSSW, to connect through a SOCKS5 proxy: git-proxy.
You can configure git to use it with
git config --global core.gitproxy "git-proxy"
git config --global socks.proxy "localhost:1080"
For more information, see git-proxy --help.