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Regular expression to extract DNS host-name or IP Address from string

Example

package main

import (
	"fmt"
	"regexp"
)

func main() {
	str1 := `Proxy Port Last Check Proxy Speed Proxy Country Anonymity 118.99.81.204
	118.99.81.204 8080 34 sec Indonesia - Tangerang Transparent 2.184.31.2 8080 58 sec 
	Iran Transparent 93.126.11.189 8080 1 min Iran - Esfahan Transparent 202.118.236.130 
	7777 1 min China - Harbin Transparent 62.201.207.9 8080 1 min Iraq Transparent`

	re := regexp.MustCompile(`(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}`)

	fmt.Printf("Pattern: %v\n", re.String()) // print pattern
	fmt.Println(re.MatchString(str1)) // true

	submatchall := re.FindAllString(str1, -1)
	for _, element := range submatchall {
		fmt.Println(element)
	}
}

Output

Pattern: (25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}
true
118.99.81.204
118.99.81.204
2.184.31.2
93.126.11.189
202.118.236.130
62.201.207.9
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