Example:
<?php $value = getservbyport(137, "udp"); ?>
The same goes for getservbyname()(PHP 4, PHP 5, PHP 7, PHP 8)
getservbyport — Get Internet service which corresponds to port and protocol
   getservbyport() returns the Internet service
   associated with port for the specified
   protocol as per /etc/services.
  
portThe port number.
protocol
       protocol is either "tcp"
       or "udp" (in lowercase).
      
   Returns the Internet service name as a string,  or false on failure.
  
Example:
<?php $value = getservbyport(137, "udp"); ?>
The same goes for getservbyname()