Sometimes people run sshd on a non-standard port. It takes time to scan an IP block, and scanning each host for all 65,535 ports makes it take even longer. Most scanning scripts and utilities target common known open ports, like telnet, smb, and ssh. For this reason someone might opt to run sshd on a port other than 22. This is a problem if you are using git over ssh to connect to one of these repositories.
Add the follwing to your ssh config:
cat >>/home/<yourusername>/.ssh/config << EOF
Host <git server IP address>
Port <obscure sshd port number>