BRev Port 5060 — SIP
SIP sets up, modifies and tears down calls; the audio itself travels separately over RTP on a high UDP range. Port 5060 carries the signalling in the clear on both UDP and TCP, which means extension numbers, caller identities and the authentication exchange are readable on the path, and 5061 is the TLS-protected equivalent.
What makes this port distinctive is the economics of attacking it. An exposed PBX is scanned continuously by tools like SIPVicious that enumerate extensions and then guess their passwords, and a single compromised extension is used to place international calls — real money, accumulating hourly, usually discovered on a bill. Unlike most breaches this one has an immediate cash cost, which is why our reference marks it care and why the mitigations are so specific.
Those mitigations: extension numbers that are not the same as the SIP username, long random passwords (an extension is not a person and does not need a memorable one), fail2ban on the SIP log, international dialling disabled by default and enabled per extension, source restrictions where the trunk provider allows it, and TLS on 5061 with SRTP for the media. A PBX with the default 100/101/102 extensions and matching passwords will be found within days.
Port 5060 at a glance
| Field | Value | Detail |
|---|---|---|
| Port | 5060 | Registered |
| Service | SIP | VoIP call signalling, unencrypted. (TCP and UDP) |
| Category | Infrastructure | the plumbing: DNS, directory, routing, monitoring |
| Exposure | Care | Expose with care |
Should port 5060 face the internet? Public SIP is scanned relentlessly for toll fraud. Use TLS (5061), fail2ban and strong extensions.
Legitimately public in some setups, but only hardened — current version, real authentication, rate limits, and ideally an allow-list.
What commonly goes wrong
Calls connect but there is no audio, or audio only one way
Signalling and media are separate. SIP negotiated the call on 5060; the RTP stream runs on a high UDP range that NAT and firewalls handle badly, and one-way audio is the signature of that. Configure the PBX with its public address and RTP port range, permit that range, and use a session border controller or a STUN/ICE-capable setup rather than SIP ALG — which frequently makes it worse.
Unexplained international calls on the bill
Assume an extension was compromised. Disable international dialling globally and re-enable per extension, rotate every extension password, check for registrations from addresses you do not recognise, and look for forwarding rules or dialplan entries that were added. The scanning that found you does not stop after you rotate the one account.
Check port 5060 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 5060 — swap example.com for the host you are actually testing.
Is port 5060 reachable on another host?
nc -vz example.com 5060"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 5060 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 5060Read TcpTestSucceeded: True = open. It is built in — nothing to install.
telnet example.com 5060A 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:5060Handy when telnet is not installed: "Connected to …" proves the TCP handshake, without curl trying to speak HTTP.
What on this machine is holding port 5060?
sudo ss -tlnp | grep :5060Lists the listening socket and the PID/program holding it. Drop sudo and you get the socket but not the process name.
sudo lsof -i :5060The macOS answer to "address already in use". Kill it with `kill -9 <PID>` once you are sure what it is.
netstat -ano | findstr :5060The 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 | |
|---|---|---|---|---|---|
| 5060 | tcp/udp | SIP | VoIP call signalling, unencrypted.Public SIP is scanned relentlessly for toll fraud. Use TLS (5061), fail2ban and strong extensions. | Carebrowser-blocked |
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 it safe to expose port 5060?
Only with real hardening: strong per-extension credentials, extension names that are not guessable numbers, fail2ban, disabled international dialling by default and ideally a session border controller. Otherwise it is a standing toll-fraud risk.
What is the difference between 5060 and 5061?
5060 is SIP in the clear (UDP and TCP); 5061 is SIP over TLS. Use 5061 with SRTP for the media if signalling crosses any network you do not control.
Why are there constant registration attempts in my PBX log?
Automated SIP scanners sweeping for reachable PBXes and guessing extensions. It is background noise on any exposed 5060 — but each attempt is a toll-fraud attempt, so the credentials behind it have to be genuinely strong.