Get a public ip address from client on server

get-client-ip-address.ts

const LOCAL_IPV4_REGEX = /(^127\.)|(^192\.168\.)|(^10\.)|(^172\.1[6-9]\.)|(^172\.2[0-9]\.)|(^172\.3[0-1]\.)|(^::1$)|(^[fF][cCdD])/
const LOCAL_IPV6_REGEX = /(([0-9a-fA-F]{1,4}:){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,7}:|([0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}:){1,3}(:[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:((:[0-9a-fA-F]{1,4}){1,6})|:((:[0-9a-fA-F]{1,4}){1,7}|:)|fe80:(:[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|::(ffff(:0{1,4}){0,1}:){0,1}((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])|([0-9a-fA-F]{1,4}:){1,4}:((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))/

export function getClientIPAddress() {
  let addrInfo, ifaceDetails
  let localIPInfo: string = ''
  //Get the network interfaces
  const networkInterfaces = require('os').networkInterfaces()
  //Iterate over the network interfaces
  for (let ifaceName in networkInterfaces) {
    ifaceDetails = networkInterfaces[ifaceName]
    //Iterate over all interface details
    for (let _i = 0, _len = ifaceDetails.length; _i < _len; _i++) {
      addrInfo = ifaceDetails[_i]
      if (
        addrInfo.family === 'IPv4' &&
        LOCAL_IPV4_REGEX.test(addrInfo.address)
      ) {
        localIPInfo = addrInfo.address
      } else if (
        addrInfo.family === 'IPv6' &&
        LOCAL_IPV6_REGEX.test(addrInfo.address)
      ) {
        if (!addrInfo.address.startsWith('fe80')) {
          localIPInfo = addrInfo.address
        }
      }
    }
  }
  return localIPInfo
}