$ git clone git@github.com:xxxxx/xxxx.git my-awesome-proj
Cloning into 'my-awesome-proj'...
ssh: connect to host github.com port 22: Connection timed out
fatal: Could not read from remote repository.

$ # This should also timeout
$ ssh -T git@github.com
ssh: connect to host github.com port 22: Connection timed out

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

# # Override SSH settings
# vim ~/.ssh/config
# Add section below to it
# https://gist.github.com/Tamal/1cc77f88ef3e900aeae65f0e5e504794
Host github.com
  Hostname ssh.github.com
  Port 443

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

$ git clone git@github.com:xxxxxx/xxxxx.git my-awesome-proj
Cloning into 'my-awesome-proj'...
remote: Enumerating objects: 15, done.
remote: Counting objects: 100% (15/15), done.
remote: Compressing objects: 100% (14/14), done.
remote: Total 15 (delta 0), reused 15 (delta 0), pack-reused 0
Receiving objects: 100% (15/15), 22.90 KiB | 4.58 MiB/s, done.