How do I control who can come in to my tunnel?

I have Cloudfare tunnel that connects cloudfare to my private server. I found that there are unsolicited login attempts to my server. Is there a way to stop that?

Related to Cloudflare Zero Trust, where tunnels are part, you could Access. You can block most of your ports on your server firewall, as the tunnel operates from within the firewall. Also, check FAQs for guidance.