PC:~$ ssh git@github.com
ssh: connect to host github.com port 22: Connection timed out
解决办法：（linux下）
~$ cd ~
~$ cd .ssh/
~$ touch config
在.ssh目录下创建一个config文件，输入如下内容：
Host github.com
User xxx@163.com （你注册github时的邮箱，这里使用注册的用户名也行）
Hostname ssh.github.com
PreferredAuthentications publickey
IdentityFile ~/.ssh/id_rsa
Port 443
可以把以上内容拷到config文件里面，注意修改你的邮箱，保存并关闭
进行测试是否连接上github.com
PC:~/.sshcd PC: ssh -T git@github.com
The authenticity of host ‘[ssh.github.com]:443 ([207.97.227.248]:443)’ can’t be established.
RSA key fingerprint is 16:27:ac:a5:76:28:2d:36:63:1b:56:4d:eb:df:a6:48.
Are you sure you want to continue connecting (yes/no)? y
Please type ‘yes’ or ‘no’: yes
Warning: Permanently added ‘[ssh.github.com]:443,[207.97.227.248]:443’ (RSA) to the list of known hosts.
Hi zhou411424! You’ve successfully authenticated, but GitHub does not provide shell access.
出现Hi xxx!……表示连接成功