To determine if an IP address is being blocked or if SSH traffic is being blocked, I would do the following:
Check the firewall settings on the computer or network. This can be done by accessing the router or firewall settings and looking for any rules that block specific IP addresses or traffic on specific ports (such as port 22 for SSH traffic).
Try to access the computer using the IP address from a different device or location. If the connection is refused or times out, it could be an indication that the IP address is being blocked.
Try to connect to the computer using SSH from a different device or location. If the connection is refused or times out, it could be an indication that SSH traffic is being blocked.
Check the system or application logs for any error messages or alerts related to blocked IP addresses or traffic.
To prevent a host from being allowed to access a system for SSH, I would do the following:
Configure the firewall to block incoming traffic on port 22 from the specific IP address or range of IP addresses.
Configure the SSH server to only accept connections from specific IP addresses or ranges of IP addresses.
Use an intrusion detection system (IDS) or intrusion prevention system (IPS) to monitor and block attempts to connect to the SSH server from unauthorized IP addresses or ranges of IP addresses.
Use access control lists (ACLs) to limit access to the SSH server to specific users or groups of users.
Use a combination of these methods for maximum security, such as using a firewall to block traffic from unauthorized IP addresses, and then using access controls to limit the users that can connect to the server once the traffic is allowed.