Port / TCP/UDP
5060SIP
SIP negotiates voice and video calls for VoIP phones, PBXs, and SIP trunks.
If it is internet-facing: Finding 5060 open to the internet is a finding in its own right — it warrants an explanation, not just a rule.
Exposure
Behind a gateway
Transport
Cleartext
Risk if public
High
Exposure verdict
Port 5060 should sit behind a reverse proxy, VPN, or source allow-list rather than being forwarded at the perimeter. Publishing it directly puts an administrative or internal interface on the open internet.
Traffic crosses the network readable and modifiable. Anything sensitive on this port needs a tunnel, a VPN, or a different protocol.
Registered with IANA on request, but bindable by any unprivileged user. Registration records intent — it does not reserve the port, so collisions between products are common.
Grouped with the other messaging & media ports so a rule written for one can be checked against its neighbours.
What actually goes wrong
2 notes- Exposed SIP is scanned constantly for extension enumeration and registration brute force; successful toll fraud is expensive within hours.
- Rate-limit registrations with fail2ban and restrict trunks to the provider's addresses.
Recommended firewall rule
Allow only from 10.0.0.0/8, drop the rest
Swap in the CIDR your administrators or application tier actually come from — the point is that the default answer is no.
ufw
sudo ufw allow from 10.0.0.0/8 to any port 5060 proto tcp
sudo ufw allow from 10.0.0.0/8 to any port 5060 proto udpiptables
sudo iptables -A INPUT -p tcp -s 10.0.0.0/8 --dport 5060 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 5060 -j DROP
sudo iptables -A INPUT -p udp -s 10.0.0.0/8 --dport 5060 -j ACCEPT
sudo iptables -A INPUT -p udp --dport 5060 -j DROPIf you do need it open to everyone
sudo ufw allow 5060/tcp
sudo ufw allow 5060/udpWrite down why. An unexplained allow rule outlives the person who added it, and the next reviewer has no way to tell a deliberate exception from an accident.
Check what is really there
Listening locally
sudo ss -tulpn 'sport = :5060'The bind address is the answer that matters: 127.0.0.1 is local-only, 0.0.0.0 and :: mean every interface.
Listening (macOS)
sudo lsof -nP -iTCP:5060 -sTCP:LISTENmacOS ships lsof rather than ss; this names the owning process and user.
From outside
nmap -sSUV -Pn -p 5060 <host>A version probe confirms whether SIP is actually what answers, rather than trusting the number. Only scan hosts you are authorised to test.
Reachability
nc -vz <host> 5060The quick yes/no when you only need to know whether a path exists through the firewall.
The safer path
port 5061Move to port 5061 — SIP over TLS
SIP over TLS does the same job with the session protected from the first byte, so there is no plaintext phase for an on-path attacker to read or strip. Migrating is usually a client configuration change plus a firewall swap.