Is a TCP port open: 1–65535, 443, 22 or a custom port. Open, closed or timeout with latency.
Common TCP ports
The shortcut list and the number box share the range 1–65535. Open means a process accepted TCP, not a software version or a CVE.
Port
Service
Typical use
22
SSH
Remote shell. Open means management access; prefer keys over passwords.
25
SMTP
Mail transfer. Home ISPs often block 25; 587/465 is enough to send.
53
DNS (TCP)
TCP 53 is for zone transfers or large answers. UDP 53 is the recursive tool.
80
HTTP
Cleartext web. Most sites redirect to 443.
443
HTTPS
TLS web. Certificate and headers are the SSL / header tools.
465
SMTPS
Mail submission with implicit TLS.
587
Submission
STARTTLS send. Gmail/Outlook clients use this.
993
IMAPS
Encrypted IMAP. 143 is plaintext.
2083
cPanel
Hosting panel over HTTPS. 2082 is cleartext, 2087 is WHM.
3306
MySQL
Database. Do not expose it; use a security group or SSH tunnel.
3389
RDP
Windows desktop. A brute-force target; put it behind VPN.
5432
PostgreSQL
Same as MySQL: should not face the internet.
6379
Redis
Cache. Unauthenticated open Redis is a common leak.
8080
HTTP-alt
Dev servers, proxies, Tomcat. You can also type 8080 in the box.
8443
HTTPS-alt
Panels and Java HTTPS. Paste host:8443 if you like.
What does “TCP port open” mean?
TCP needs a three-way handshake (SYN / SYN-ACK / ACK). This tool sends a SYN to the port you give. SYN-ACK means open: something is listening. RST (connection refused) is closed. No reply until the timer fires is timeout — often a drop rule or filter.
The probe leaves the iptool.tr host, not your browser. The target’s log shows our egress IP. If your home firewall allows SSH only from you, 22 looks closed here. This is not a pentest, banner grab or UDP scan.
How do I check a custom port?
Type any integer 1–65535. The chips cover 8080, 8443, 2222, 2083, 5432 and similar; anything else (9000, 25565, 32400) goes in the box. Paste example.com:8443 or https://panel.example.com:2083 to fill the port from the host field.
For IPv6 use [2001:db8::1]:443. One port per request. Scanning 1–1024 in one go is out of scope and often unauthorised.
Open, closed, timeout
Open: a process accepted the handshake. 443 open means HTTPS is listening, not that the certificate is valid (use SSL checker). 22 open is SSH; weak passwords are invisible here.
Closed: the host answered but nothing listens (RST). Timeout: the packet was dropped. Closed vs filtered matters in security groups; timeout is its own row.
Limits and permission
10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, 127.0.0.0/8 and similar private ranges are refused (SSRF). You need a public IP or a name with a public A/AAAA.
Use it only on systems you own or may test. Free accounts get one host; Pro asks the same port on 256 addresses in a /24. Rate limits cut abuse.
Frequently asked questions
Closed vs filtered?
RST is usually closed. No reply is often a firewall (filtered). This tool shows timeout separately.
Can I type my own port?
Yes. Any TCP port 1–65535. If it is not in the list, type it or paste host:port.
Can I scan many ports?
No, one port. Bulk port scanning is out of scope. Pro /24 asks the same port on each IP in the net.
UDP?
No, TCP connect. DNS 53/UDP is the recursive-DNS tool.
Can I scan localhost?
No. Loopback and private nets are refused.
Does it find vulnerabilities?
No. It only says whether a TCP handshake succeeded and how many milliseconds it took.
Open at home, closed here?
The probe is from this server. If the host allows only your IP, it looks closed from outside.
What are 8080 and 8443?
Common alternate HTTP/HTTPS. Reverse proxies, panels and dev servers often listen there.