Port18/UDP

msp

Port

Protocol

UDP

What is port 18?

Port 18/UDP is a Well-Known port, assigned by IANA for widely recognized services. It is associated with the msp service.

Message Send Protocol (historic)

Useful commands

nmapnmap -p 18 -sV example.com

netcatnc -zv example.com 18

curlcurl -v http://example.com:18/

telnettelnet example.com 18

bash(echo > /dev/udp/example.com/18) 2>/dev/null

Firewall commands

UFWAllow

sudo ufw allow 18/udp

Deny

sudo ufw deny 18/udp

iptablesAllow

sudo iptables -A INPUT -p udp --dport 18 -j ACCEPT

Deny

sudo iptables -D INPUT -p udp --dport 18 -j ACCEPT

firewalldAllow

sudo firewall-cmd --permanent --add-port=18/udp

WindowsAllow

netsh advfirewall firewall add rule name="Open Port 18" dir=in action=allow protocol=UDP localport=18

Security Risks

Unauthorized access to the service
Data exposure if the service is unauthenticated
Outdated versions with vulnerabilities
Incorrect service configuration

Frequently Asked Questions

What service runs on port 18/UDP?

Port 18/UDP is associated with the msp service. Message Send Protocol (historic)

Is it safe to expose port 18 to the Internet?

It depends on the service and configuration. Port 18 (msp) is a Well-Known port. If you need to expose it, keep the service updated, use strong authentication, and configure a firewall. It's always recommended to restrict access by IP when possible.

How do I check if port 18 is open?

You can use nmap: `nmap -p 18 -sV example.com`, netcat: `nc -zv example.com 18`, or the bash command: `(echo > /dev/udp/example.com/18) 2>/dev/null && echo "Open" || echo "Closed"`.

How do I open or close port 18 on my firewall?

On Linux with UFW: `sudo ufw allow 18/udp` (open) or `sudo ufw deny 18/udp` (close). With iptables: `sudo iptables -A INPUT -p udp --dport 18 -j ACCEPT`. On Windows: `netsh advfirewall firewall add rule name="Open Port 18" dir=in action=allow protocol=UDP localport=18`.