Some Mac users have found that SSH is not working on their Mac since updating to macOS Ventura 13 or later. Typically, when trying to access another server via SSH, you’ll see an error message something like “no matching host key type found. Your offer: ssh-rsa“.
The obvious reason for this problem is that the version of OpenSSH that ships with MacOS Ventura disables RSA signatures by default, so you can solve the problem by either using a more secure hash or just allowing RSA signatures. We’ll show you how to do the latter.
We’ll use nano because it’s simple and easy to use, but feel free to use vi/vim or any text editor of your choice.
How to fix SSH not working with RSA signatures on macOS Ventura
We will modify the ssh_config file to allow the RSA host key again, how to do this you can find out here.
Open the terminal (from Spotlight or from the Utilities folder) and enter the following command string:
sudo nano /etc/ssh/ssh_config
You need to authenticate yourself with the admin password.
Scroll all the way down in the ssh_config file, then add the following lines to the end of ssh_config:
HostkeyAlgorithms +ssh-rsa
PubkeyAcceptedAlgorithms +ssh-rsa
Press Ctrl+O to save and Ctrl+X to exit.
Try using SSH again to connect to a server with RSA keys, it should work as intended.
While you’re at the command line, you can always enable ssh from the terminal as well if you want to allow incoming ssh connections to your Mac. For example, you may want to access your Mac from the command line from an iPad or other computer, and this would make that possible.
This error can also occur after confirming that SSH is enabled for macOS, which shouldn’t affect outgoing SSH connections anyway, but some users are reporting that their difficulties have been resolved, so give that a try as well and it would obviously help make a difference if the computer you are trying to connect to is a Mac running SSH, as some Mac users have found that SSH is disabled by default in macOS Ventura even if it was previously enabled, before updating the system software.
