remotehost endpoint needs to configure firewall for benchmark server

[atheurer]

Most hosts reachable by ssh have some kind of firewall configured that usually blocks benchmark servers from receiving connections outside the host. This needs to be fixed by the remotehost endpoint. When a benchmark server starts, oit sends its IP and ports it will use as a roadblock message. The endpoint can find this message once the endpoint-start roadblock is complete.

A remotehost endpoint will need to identify all possible types of firewall configurations, which could include firewalld, or some other implementation that might configure iptables (or something else). This could get complicated, but at least the most common scenarios should be handled.