github超时[ssh: connect to host github.com port 22: Operation timed out]

$ git push

ssh: connect to host github.com port 22: Operation timed out
fatal: Could not read from remote repository.

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

1. 先测试可用性
   ssh -T -p 443 git@ssh.github.com
   如果出现下面提示说明可用

Hi XXXX! You've successfully authenticated, but GitHub does not provide shell access.

如果出现下面的提示，直接输入yes回车即可

The authenticity of host '[ssh.github.com]:443 ([20.205.243.160]:443)' can't be established.
...
...
Are you sure you want to continue connecting (yes/no/[fingerprint])?

2. 创建或修改 ~/.ssh/config 加入以下内容

$ vim ~/.ssh/config

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

3. 再次测试，出现下面信息就说明成功了
   ssh -T git@github.com

Hi XXXX! You've successfully authenticated, but GitHub does not provide shell access.