Global probes
Confirm connectivity from a neutral network to rule out local firewall rules or ISP filtering.
Instant port testing
Port Checker: check any port in secondsFree Online Tool
Port Checker is the dedicated port checker for SRE, DevOps, and security engineers to validate connectivity, share common port checker knowledge, and respond to outages faster. This port checker keeps your investigations focused on the exact services that matter.
- No installation required
- Works with IPv4, IPv6, and hostnames
- Detailed guides for 20+ critical ports
- Share verified port checker results in seconds with Port Checker
- Free to use and share
Free online port checker
Free Online ToolEnter an IP address or hostname with a target port to verify connectivity from our cloud-based port checker probe. The Port Checker instantly returns context you can trust.
Always confirm you have permission before scanning or testing endpoints you do not own.
Instant port testing
Engineered for the Port Checker workflow
Modern operators need fast answers. Port Checker combines live port checker testing, best practices, and documentation in one place so the port checker workflow stays consistent for every team member.
Actionable guides
Each featured port includes setup checklists, troubleshooting flows, and security reminders.
Operations ready
Crafted for on-call teams with responsive design, dark mode, and multilingual support.
Instant port testing
Popular ports at a glance
Jump straight into the guides for the ports Port Checker users ask about most often, then run a port checker against each service to confirm availability.
HTTPS 443
Port 443 · TCP
Encrypt web applications with TLS certificates on port 443.
SFTP
Port 22/115 · TCP
Transfer files securely through SSH tunnels.
SSH
Port 22 · TCP
Manage servers remotely with encrypted shell access.
SMB 445
Port 445 · TCP
Serve file shares and authentication over TCP.
SMB over TCP
Port 445 · TCP
Serve file shares and authentication over TCP.
HTTP 80
Port 80 · TCP
Serve web traffic without encryption on port 80.
DNS 53
Port 53 · UDP / TCP
Provide name resolution for infrastructure.
Port 22
Port 22 · TCP
Manage servers remotely with encrypted shell access.
Telnet
Port 23 · TCP
Legacy plaintext remote console access.
DNS Services
Port 53 · UDP / TCP
Provide name resolution for infrastructure.
SNMP
Port 161/162 · UDP
Monitor infrastructure with SNMP polling and traps.
Samba
Port 445 · TCP
Serve file shares and authentication over TCP.
RDP
Port 3389 · TCP
Provide Windows remote desktop access.
NTP
Port 123 · UDP
Distribute precise time to fleet devices.
ICMP
Port ICMP · ICMP
Test reachability and latency with ICMP echo.
FRP
Port 7000 · TCP
Expose internal apps through reverse tunnels.
Minecraft Server
Port 25565 · TCP
Host multiplayer Minecraft worlds.
Port 3389
Port 3389 · TCP
Provide Windows remote desktop access.
FTP
Port 20/21 · TCP
Serve classic file transfers on ports 20/21.
IMAP 143
Port 143 · TCP
Retrieve email messages from servers.
SQL Services
Port 1433 · TCP
Expose relational databases to applications.
Instant port testing
Frequently asked questions
Get clarity on how port forwarding works, how to interpret Port Checker results, and why some ISPs block certain ports.
What is port forwarding?
Port forwarding maps an external port on your router or firewall to an internal service. It enables access from the internet to devices on private networks.
Why do ISPs block common ports?
Consumer ISPs often block ports such as 25, 80, or 445 to limit malware and spam. Contact your provider about business plans if you need them opened.
How often should I recheck ports?
Verify ports after network changes, firewall updates, or security incidents. Automate recurring checks for mission-critical services.