BRev Port 2222 — SSH on an alternate port
Nothing owns port 2222 by standard. It is the port SSH is moved to, chosen because it is memorable, above 1024 (so an unprivileged process can bind it during testing) and not in the way of anything common. DirectAdmin’s control panel also uses it, and Docker containers publishing an internal sshd map to it constantly — so “what is listening on 2222” has three plausible answers on the same box.
The honest accounting of the move: it removes the untargeted background scanning almost entirely, which makes your auth log readable again and makes a real intrusion attempt visible instead of buried. It does not reduce your exposure to anyone who is actually looking at you, because a full-range scan of one host is a few seconds’ work. Our reference marks 2222 exactly as it marks 22 — care — because the rules that matter (keys only, no root login, patched OpenSSH) are unchanged by the number.
It is also not free. Every client, deploy script, Ansible inventory, rsync invocation, Git remote and monitoring check has to learn the new port, and each one has its own syntax for it: ssh -p 2222, scp -P 2222 (capital P), rsync -e "ssh -p 2222", and ssh://git@host:2222/repo for Git. A Host block in ~/.ssh/config is worth writing on day one so nobody has to remember.
Port 2222 at a glance
| Field | Value | Detail |
|---|---|---|
| Port | 2222 | Registered |
| Service | SSH alt | SSH moved off 22 — also DirectAdmin. (TCP) |
| Category | Remote access | shells, desktops and VPNs |
| Exposure | Care | Expose with care |
Should port 2222 face the internet? Cuts log noise, not risk: the same key-only, no-root rules apply.
Legitimately public in some setups, but only hardened — current version, real authentication, rate limits, and ideally an allow-list.
What commonly goes wrong
You changed sshd_config and locked yourself out
The rule that saves people: keep the existing SSH session open, add the new Port line alongside the old one (sshd accepts several Port directives, so it listens on both), restart, and prove the new port works in a second window before removing the old. On SELinux systems the restart fails outright until the port is labelled — semanage port -a -t ssh_port_t -p tcp 2222 — and on a cloud host the security group needs the rule before anything can reach it.
It works from inside the network and not from outside
A non-standard high port is far more likely to be blocked by the network the client is on than by yours. Corporate and hotel networks routinely allow 22 and deny everything unrecognised outbound. Test from a phone on mobile data to separate “my server is wrong” from “this café blocks it”; port 443 with SSH multiplexing is the usual escape hatch.
Check port 2222 yourself
No browser can open a raw TCP socket, so no web page can honestly tell you whether this port is open on a remote host. These are the real commands, generated for port 2222 — swap example.com for the host you are actually testing.
Is port 2222 reachable on another host?
nc -vz example.com 2222"succeeded!" means the TCP handshake completed — the port is open. "Connection refused" is closed; a hang until timeout means filtered (a firewall dropped it silently).
nmap -Pn -p 2222 example.comThe only common tool that distinguishes open / closed / filtered. -Pn skips the ping sweep, so it still works against hosts that ignore ICMP.
Test-NetConnection example.com -Port 2222Read TcpTestSucceeded: True = open. It is built in — nothing to install.
telnet example.com 2222A blank screen or a banner means it connected. "Connection refused" means closed. Quit with Ctrl-] then `quit`.
curl -v --max-time 5 telnet://example.com:2222Handy when telnet is not installed: "Connected to …" proves the TCP handshake, without curl trying to speak HTTP.
What on this machine is holding port 2222?
sudo ss -tlnp | grep :2222Lists the listening socket and the PID/program holding it. Drop sudo and you get the socket but not the process name.
sudo lsof -i :2222The macOS answer to "address already in use". Kill it with `kill -9 <PID>` once you are sure what it is.
netstat -ano | findstr :2222The last column is the PID. Match it in Task Manager’s Details tab, or `taskkill /PID <pid> /F`.
No web page can tell you whether a port is open on a remote host
A browser cannot open a raw TCP socket — there is no API for it, by design. So a site that reports “port 3389 is OPEN on 203.0.113.10” is not checking from your browser; it is asking its own server to scan on your behalf. That works, but it means their server sees the host you asked about, scans from their address rather than yours, and answers a question about their network path, not yours.
We don't have a server here and won't pretend to. So this page does three honest things instead:
| Port | Proto | Service | What it is | Exposure | |
|---|---|---|---|---|---|
| 2222 | tcp | SSH alt | SSH moved off 22 — also DirectAdmin.Cuts log noise, not risk: the same key-only, no-root rules apply. | Care |
http://host:port/ and times it. A connection that is established proves a socket is open; an instant refusal usually means nothing is listening; anything else is honestly reported as “can't tell”. Each attempt gives up after 2.5s.nc -vz example.com 443
nmap -Pn -p 443 example.com
telnet example.com 443
curl -v --max-time 5 telnet://example.com:443
This page cannot answer that, and neither can any other page — from your browser. Opening a TCP connection to an arbitrary host and port is not something JavaScript is allowed to do. Every “open port checker” that gives you a green tick is running the scan on their server. Which is fine, as long as you know what you are agreeing to: they learn which host and port you were worried about, and the answer they give you is about the route from their data centre — not from the internet as your users see it.
What to do instead
Run the check from outside your own network. Copy an nmap or nc line from the card above and run it from a machine that is not behind the same router — a phone on mobile data with a terminal app, a cheap VPS, a colleague's laptop. Running it from inside the LAN tests the LAN, not the internet, and will happily say “open” while the world sees nothing.
Then check the thing that is actually blocking it, in this order: the service is bound to0.0.0.0 and not 127.0.0.1 · the host firewall (ufw, firewalld, Windows Defender Firewall) · the cloud security group or the router's port-forward rule · and finally your ISP, which commonly blocks 25, 80 and 445 on residential lines whatever you configure.
What a browser genuinely can verify
One thing: that an HTTPS service answers. If what you actually want to know is “is my site up and how fast is it”, the latency test measures real round trips to a CORS-open URL. If the name doesn't resolve, or resolves somewhere unexpected, that is a DNS problem, not a port problem — and it is the more common cause of “my port is closed” than an actual firewall.
An IP address finds the machine; a port picks which program on it gets the traffic. TCP sets up a connection first — a handshake, ordered delivery, retransmission — which is why the web, email and SSH use it. UDP just sends the packet with no handshake and no guarantee it arrives, which is why DNS, video calls and games use it: late data is worse than lost data.
That difference is why a UDP port is so much harder to test. TCP either completes a handshake or it doesn't, so a tool can tell you. A UDP service that has nothing to say to an unexpected packet stays silent — and silence looks identical to a firewall dropping it.
The three ranges
0–1023Assigned by IANA to core services. On Unix, binding one needs root (or CAP_NET_BIND_SERVICE).1024–49151Registered by vendors for their applications. Any user can bind these — which is why every dev server lives here.49152–65535Never assigned. The OS hands these out as the SOURCE port of your outgoing connections. (Linux actually uses 32768–60999 by default.)Closed is not the same as filtered
Closed means the host answered: the packet arrived, nothing is listening, and you got an immediate refusal (a TCP RST). Filtered means nothing answered at all — a firewall dropped your packet in silence, so you wait for a timeout and learn nothing. The difference matters: closed proves the host is reachable and the port is free; filtered tells you only that something between you and it is discarding traffic.nmap reports the two separately. A browser cannot distinguish them, which is why this page reports a timeout as “can't tell” rather than guessing.
The one habit worth keeping
Bind services to 127.0.0.1 instead of 0.0.0.0 unless something outside the machine genuinely needs them, and reach them over SSH or a VPN. Every database on the never-expose list above ships with that advice, and the leaks all begin the same way: a default bind address, a cloud instance with a public IP, and a scanner that found it within the hour.
The blocked-port list this page uses is the WHATWG Fetch Standard's “bad port” table — the ports every browser refuses to connect to (Chrome calls it ERR_UNSAFE_PORT). Local probing is additionally gated by Chrome's Local Network Access permission, which replaced Private Network Access and ships in Chrome 142.
FAQ
Is port 2222 more secure than 22?
Quieter, not more secure. Automated botnets mostly skip it, so brute-force attempts in your logs drop by orders of magnitude. An attacker who has chosen your host scans every port and finds it in seconds. Treat the change as log hygiene, never as a control.
Something is listening on 2222 and I did not configure SSH there
Check DirectAdmin (its panel binds 2222) and any Docker container publishing 2222:22. Both are ordinary. If neither explains it, find the process — the local commands on this page name the PID holding the port — before assuming the worst.
Does a non-standard port break SFTP or Git?
No, but each tool spells the port differently: scp uses -P, ssh uses -p, rsync needs -e "ssh -p 2222", and Git needs the ssh:// form with the port. A Host entry in ~/.ssh/config sets it once for all of them.