One small addition to Tupy's answer, you may need to add the port number for your repository host:

ssh-keyscan -p 8888 -t rsa domain.com >> ~/.ssh/known_hosts

If you have another machine that does have remote access you can find the port number by viewing ~/.ssh/known_hosts:

[user]$ less ~/.ssh/known_hosts
[domain.com]:8888,[000.00.000.000]:8888 ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCi...

One small addition to Tupy's answer, you may need to add the port number for your repository host:

ssh-keyscan -p 8888 -t rsa domain.example >> ~/.ssh/known_hosts

If you have another machine that does have remote access you can find the port number by viewing ~/.ssh/known_hosts:

[user]$ less ~/.ssh/known_hosts
[domain.example]:8888,[000.00.000.000]:8888 ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCi...