Protocols

Protocols

Protocol	url format	Example	Success condition
http / https	hostname or full URL	example.com/health	HTTP status below 400
tcp	host:port	example.com:443	Connection established
udp	host:port	1.1.1.1:53	A response is received
dns	hostname	example.com	At least one A/AAAA record found
ping	plain IP address	1.1.1.1	Matching ICMP echo reply received

http / https

Sends a GET request. The probe is ok when the status code is below 400.

pf.watch({ protocol: "https", url: "example.com/health", interval: 10000 });

tcp

Opens a TCP connection and measures the time to connect.

pf.watch({ protocol: "tcp", url: "example.com:443" });

An invalid host:port format gives the error Invalid host:port format. A connection that does not open in time gives TCP connection timeout.

udp

Sends a small UDP packet and waits for a response.

pf.watch({ protocol: "udp", url: "1.1.1.1:53" });

UDP is connectionless. A target that silently drops the packet looks the same as a target that is down.

dns

Resolves A/AAAA records for a hostname.

pf.watch({ protocol: "dns", url: "example.com" });

ping

Raw ICMP echo request, done by a native C addon.

pf.watch({ protocol: "ping", url: "1.1.1.1" });

• Linux only for now
• IP addresses only, hostnames are not resolved
• Works without root on most systems

Full details: ICMP-Ping.