DNS Latency Check

10_dns_list.txt

209.244.0.3
209.244.0.4
64.6.64.6
64.6.65.6
8.8.8.8
8.8.4.4
84.200.69.80
84.200.70.40
8.26.56.26
8.20.247.20
208.67.222.222
208.67.220.220
156.154.70.1
156.154.71.1
199.85.126.10
199.85.127.10
81.218.119.11
209.88.198.133
195.46.39.39
195.46.39.40
96.90.175.167
193.183.98.154
208.76.50.50
208.76.51.51
216.146.35.35
216.146.36.36
37.235.1.174
37.235.1.177
198.101.242.72
23.253.163.53
77.88.8.8
77.88.8.1
91.239.100.100
89.233.43.71
74.82.42.42
109.69.8.51

10_latency_check.sh

#!/bin/bash

for server in $(cat dns-list.txt); do
  echo "$(sudo ping -f -c 100 $server | grep "rtt" | tr '/' '\n' | sed -n '5p') # IP: $server";
done | sort --version-sort

20_check_clean_dns.sh

#!/bin/bash

for server in $(cat dns-list.txt); do
  if [[ `dig doesntexist.lol @$server +short | wc -l` -eq "0" ]]; then
    echo $server;
  fi
done

30_latency_check.go

package main

import (
  "fmt"
  "strings"
  "strconv"
  "regexp"
  "os/exec"
  "sort"
)

type Server struct {
  ip string
  latency float64
}

type ServerList []Server

func (s ServerList) Len() int           { return len(s) }
func (s ServerList) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
func (s ServerList) Less(i, j int) bool { return s[i].latency < s[j].latency }

func get_ping(ip string) string {
  
  r := regexp.MustCompile("icmp_seq=(\\d+) ttl=(\\d+) time=(\\d+.?\\d+) ms")
  
  cmd := "ping -c 1 -w 1 " + ip

  parts := strings.Fields(cmd)
  head := parts[0]
  parts = parts[1:len(parts)]

  out, err := exec.Command(head, parts...).Output()
  
  if err != nil {
    return "-1"
  }
  
  res := r.FindStringSubmatch(string(out))
  
  return string(res[3])
  
}

func main() {
  
  const NO_LAT = -1
  
  servers := map[string]int {
    "209.244.0.3": NO_LAT,
    "209.244.0.4": NO_LAT,
    "64.6.64.6": NO_LAT,
    "64.6.65.6": NO_LAT,
    "8.8.8.8": NO_LAT,
    "8.8.4.4": NO_LAT,
    "84.200.69.80": NO_LAT,
    "84.200.70.40": NO_LAT,
    "8.26.56.26": NO_LAT,
    "8.20.247.20": NO_LAT,
    "208.67.222.222": NO_LAT,
    "208.67.220.220": NO_LAT,
    "156.154.70.1": NO_LAT,
    "156.154.71.1": NO_LAT,
    "199.85.126.10": NO_LAT,
    "199.85.127.10": NO_LAT,
    "81.218.119.11": NO_LAT,
    "209.88.198.133": NO_LAT,
    "195.46.39.39": NO_LAT,
    "195.46.39.40": NO_LAT,
    "96.90.175.167": NO_LAT,
    "193.183.98.154": NO_LAT,
    "208.76.50.50": NO_LAT,
    "208.76.51.51": NO_LAT,
    "216.146.35.35": NO_LAT,
    "216.146.36.36": NO_LAT,
    "37.235.1.174": NO_LAT,
    "37.235.1.177": NO_LAT,
    "198.101.242.72": NO_LAT,
    "23.253.163.53": NO_LAT,
    "77.88.8.8": NO_LAT,
    "77.88.8.1": NO_LAT,
    "91.239.100.100": NO_LAT,
    "89.233.43.71": NO_LAT,
    "74.82.42.42": NO_LAT,
    "109.69.8.51": NO_LAT,
  }
  
  s := make(ServerList, len(servers))
  
  fmt.Println("Analysing pings...")
  
  i := 0
  for server := range servers {
    
    time, err := strconv.ParseFloat(get_ping(server), 64)
    
    if err == nil && time != NO_LAT {
      s[i] = Server { server, time }
    } else {
      s[i] = Server { server, NO_LAT }
    }
    
    i++
    
  }

  sort.Sort(s)
  
  fmt.Println("\r\nResults:\r\n")
  
  for _, k := range s {
    
    if ( k.latency != NO_LAT ) {
      fmt.Printf("%s \t%f\r\n", k.ip, k.latency)
    }
    
  }
  
}