Guides tagged “firewall”

Step-by-step MdmHost guides about firewall, sorted A-Z.

91 guides · page 4 of 5

  • Port forwarding and masquerading with firewalld

    Forward a port to another local port or to a different host with firewalld, enable masquerading so replies find their way back, then test and make the rules permanent.

    AdvancedLinux server4 min read

  • Port forwarding and NAT with UFW before.rules

    Forward a public port on your VPS to a backend server or VPN client with UFW. Turn on IP forwarding, add a nat table to before.rules, allow routed traffic and test from outside.

    AdvancedLinux server5 min read

  • Port open in the firewall but still unreachable: how to fix it

    You allowed a port in the firewall but connections still fail. Work through each layer, from the listening address to the server and client networks, to find the real block.

    Intermediate5 min read

  • Ports, protocols and TCP vs UDP explained

    How ports and protocols let one server run many services, the real difference between TCP and UDP, and which one common services use.

    BeginnerAll hosting and VPS3 min read

  • Protect SSH from brute-force attacks with Fail2ban

    Install Fail2ban, create a safe jail.local for SSH, check which addresses are banned and unban yourself if you mistype a password too often.

    IntermediateLinux server2 min read

  • Protect your website with Cloudflare WAF custom rules

    Use Cloudflare WAF custom rules to block bad countries, bots and attack paths, challenge visitors to wp-login.php, and allow your own IP, before traffic reaches your hosting.

    IntermediateSites using Cloudflare2 min read

  • Put Remote Desktop behind a WireGuard VPN

    Install WireGuard on your Windows server, connect your own computer as a client, then limit the RDP port 3389 rule to the VPN subnet so only VPN users can reach the login screen.

    AdvancedWindows server5 min read

  • Rate-limit SSH and other ports with ufw limit

    Use ufw limit to slow down SSH brute-force attempts. Learn how the 6-connections-in-30-seconds rule works, apply it to a custom SSH port, pair it with Fail2ban and test it.

    BeginnerLinux server5 min read

  • RDP over UDP vs TCP: check and choose the transport

    Remote Desktop can carry your session over TCP, UDP or both. Learn how each is used, how to see which one your session runs on, and how to force TCP when UDP misbehaves.

    AdvancedWindows server5 min read

  • Read and tune UFW firewall logs

    Turn on UFW logging at the right level, find [UFW BLOCK] lines in the journal or ufw.log, read the SRC, DPT and PROTO fields and keep log volume under control.

    IntermediateLinux server5 min read

  • Read the Imunify360 Incidents log to understand attacks (root guide)

    Use the Imunify360 Incidents tab and CLI as root to see brute-force attempts, WAF hits and blocked IPs, spot patterns, and decide when to whitelist, block or tune rules.

    AdvancedcPanel server (root)2 min read

  • Restrict outgoing traffic with UFW egress rules

    Switch UFW to deny outgoing traffic by default, then allow only DNS, NTP, HTTPS and package mirrors. Block outbound SMTP and avoid breaking system updates along the way.

    AdvancedLinux server5 min read

  • Secure Remote Desktop on Windows Server

    Stop password-guessing on Remote Desktop with strong passwords, Network Level Authentication, a lockout policy and firewall rules limited to your IP.

    IntermediateWindows server3 min read

  • Set up a UFW firewall on Ubuntu and Debian

    Set safe defaults, allow SSH before switching UFW on, open only the ports you use, limit sensitive ports to your own IP, and tidy up old rules.

    BeginnerLinux server3 min read

  • Set up a UFW firewall on Ubuntu and Debian

    Enable UFW without locking yourself out, allow SSH and web ports, restrict services to specific IPs, rate-limit SSH and understand how Docker bypasses UFW.

    BeginnerLinux VPS3 min read

  • Set up the Proxmox VE firewall for the host and VMs

    Enable the built-in Proxmox firewall safely: allow the web UI and SSH first, then add datacenter, node and per-VM rules, security groups and IP sets.

    IntermediateProxmox VE2 min read

  • Stop Docker from bypassing your UFW firewall

    Docker-published ports skip UFW rules and stay open to the internet. Learn why it happens, how to bind ports to 127.0.0.1, how to filter with the DOCKER-USER chain and how to test from outside.

    AdvancedLinux server6 min read

  • Switch from CSF to the Imunify360 firewall (root guide)

    Move a cPanel server from CSF/LFD to the Imunify360 firewall as root: plan the switch, migrate allow and deny lists, open the right ports and verify nothing is locked out.

    AdvancedcPanel server (root)2 min read

  • TCP vs UDP explained for server owners

    TCP sets up a connection and guarantees delivery; UDP sends independent datagrams with no handshake. Learn the difference, which services use each and why firewall rules must name the protocol.

    Beginner5 min read

  • Test firewall changes safely with an automatic rollback

    Schedule an automatic undo before you change firewall rules. If a mistake blocks SSH, the old rules come back by themselves a few minutes later.

    IntermediateLinux server5 min read

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