操作步骤是这样的 
1， git add . 
2. git commit -m 'modify' 
3. git fetch origin 


这一步报这个错 
$ git fetch origin 
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. 

求大家帮忙