git pull 的时候发现一直连接不上。

$ git pull
ssh: connect to host github.com port 22: Connection timed out
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

一开始以为是great wall的问题，换了节点，都不成功。于是怀疑公司防火墙block了22端口。

查资料发现github支持使用443端口进行ssh： Using SSH over the HTTPS port

首先测试连通性

$ ssh -T -p 443 git@ssh.github.com
Hi xxx! You've successfully authenticated, but GitHub does not provide shell access.

没问题的话，~/.ssh/config添加配置

Host github.com
Hostname ssh.github.com
Port 443

最后ssh -T -p 443 git@ssh.github.com，测试连通性。