Test whether a remote TCP port accepts connections
Updated:
This port checker connects from our server to any public IP or hostname and reports whether each TCP port you list is open, refused or silent. Enter up to 8 ports above; for open ports it measures the TCP handshake time (SYN → SYN-ACK). Run it before you dig into login errors such as a 407 or browser settings: if the port cannot be reached, nothing further up will work.
Three possible results
Refused and timed-out ports point to different fixes. A refusal means the address is right and the service is missing; see proxy server refusing connections. Silence usually means a firewall in the path; see proxy timeout.
| Result | What happened on the wire | Usual explanation |
|---|---|---|
| OPEN, with a time in ms | Our SYN got a SYN-ACK back | A proxy daemon or another service is listening on that port |
CLOSED (refused) | The host replied with a reset (RST) | The machine is up but nothing listens on the port, or an iptables REJECT rule answered |
CLOSED (timeout) | No reply at all | A firewall such as an AWS Security Group, UFW, Cloudflare or an ISP filter dropped the packet silently |
Ports you will often test
Proxy software such as Squid, 3proxy, Dante, HAProxy and Nginx listens on well-known or high-numbered ports. These are the usual suspects; always test the exact port printed on your order.
8080,3128,8888: common HTTP and HTTPS CONNECT proxy ports, used by Squid and 3proxy.1080,1081: the traditional SOCKS4 and SOCKS5 ports, for example Dante.80,443: web servers, reverse proxies and listeners chosen to pass restrictive firewalls.- Any custom port: dedicated proxies are often assigned a high port number, so type it in rather than relying on presets.
Port checker or proxy checker?
The port checker answers a network question at layer 4: does the port accept a TCP connection? It sends no credentials. The proxy checker goes up to layer 7: it logs in through the proxy and reports the exit IP. An OPEN port that still fails in your browser points to credentials or app settings, not to the network.
Step by step
- 1
Enter the public IP or hostname
Put your proxy's IP or your server's hostname in the Target Public IP field.
- 2
List the ports
Type up to 8 ports separated by commas, for example
80, 443, 1080, 3128, 8080, or the single port from your order. - 3
Start the probe
Press Check Ports. Our server opens a real TCP connection to each port, with SSRF protection on the target.
- 4
Act on the result
OPEN but still failing in the browser? Test the full
user:passline in the proxy checker next.
Frequently asked questions
Why can't I check 127.0.0.1 or 192.168.x.x?
To prevent server-side request forgery, our server only connects to public unicast addresses. Loopback, private RFC1918 ranges and link-local addresses are refused.
The port is OPEN here but unreachable from my office Wi-Fi. Why?
Company, campus and hotel networks often block outgoing connections to non-standard ports such as 3128 or anything above 30000. Try another network, or read checking the proxy and the firewall.
Does an open port mean the proxy works?
Only that something is listening. Authentication and the exit IP are checked by the proxy checker.
Proxies with the port already open
ProxyV4 private IPv4 and static ISP proxies arrive as a working HTTP(S) ip:port:user:pass line, with 24/7 ticket support if a port will not answer.
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