5分钟教你SSL证书自动巡检与过期提醒

linwu

发布于 2023-08-13 09:37:30

5280

发布于 2023-08-13 09:37:30

文章被收录于专栏：编程时光编程时光

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引言

最近我的主站编程时光证书过期了，导致用户访问网站时出错，后面续上免费的证书，由于我是使用的免费的证书，所以证书的有效期只有一年。为了避免证书过期导致网站无法访问，我决定写一个小程序来自动检查证书的过期时间，并在证书快过期时通知我及时更换证书。

自动巡检SSL证书过期时间

我们首先定义了一个checkCertificates函数，该函数的主要任务是读取一个名为domain.txt的文件，该文件中列出了需要检查的域名和对应的IP地址。

func checkCertificates() {
 file, err := os.Open("domain.txt")
 if err != nil {
  panic(err)
 }
 defer file.Close()

 scanner := bufio.NewScanner(file)
 for scanner.Scan() {
  line := scanner.Text()
  parts := strings.Split(line, ":")
  domain := parts[0]
  ipPool := strings.Split(strings.ReplaceAll(parts[1], ",", " "), " ")
  // ipPool [43.138.235.240]
  fmt.Println("ipPool", ipPool)
  for _, ip := range ipPool {
   conn, err := tls.Dial("tcp", ip+":443", &amp;tls.Config{
    ServerName:         domain,
    InsecureSkipVerify: true, // We're only checking expiration, not validity
   })
   if err != nil {
    fmt.Printf("Error! %s\n", ip)
    fmt.Println(domain)
    continue
   }
   defer conn.Close()

   cert := conn.ConnectionState().PeerCertificates[0]
   endDate := cert.NotAfter
   currentTime := time.Now()
   remainingDays := endDate.Sub(currentTime).Hours() / 24

   fmt.Printf("ip: %s\ndomain: %s\n", ip, domain)

   sendEmail("SSL证书过期提醒", fmt.Sprintf("The certificate for domain %s (IP: %s) will expire in less than %f days!", domain, ip, remainingDays))
   if remainingDays < 7 &amp;&amp; remainingDays >= 0 {
    fmt.Println("剩余时间小于七天！请及时更换证书！")
    fmt.Printf("ip: %s, %s\n", ip, domain)
   } else if remainingDays < 0 {
    fmt.Println("证书已过期！请及时更换证书！")
   } else {
    fmt.Printf("剩余天数为：%f\n", remainingDays)
   }
  }
 }

 if err := scanner.Err(); err != nil {
  panic(err)
 }
}

邮件通知

当我们知道了证书的剩余有效期后，下一步是通知相关人员。在sendEmail函数中，我们使用了gomail库来发送邮件。

func sendEmail(subject, body string) {
    from := "linwu.hi@gmail.com"
    pass := "xxx"
    to := "linwu.hi@gmail.com"

    m := gomail.NewMessage()
    m.SetHeader("From", from)
    m.SetHeader("To", to)
    m.SetHeader("Subject", subject)
    m.SetBody("text/plain", body)

    d := gomail.NewDialer("smtp.gmail.com", 587, from, pass)

    if err := d.DialAndSend(m); err != nil {
        log.Fatal(err)
    }
}

定时任务

为了确保我们能够及时地检测到证书的状态，我们需要定期执行上述的检查任务。在main函数中，我们使用了cron库来创建一个定时任务。

func main() {
    c := cron.New(cron.WithSeconds())
    c.AddFunc("0 0 0 * * ?", checkCertificates) // 每日凌晨0点执行, 检查证书过期时间，通知到老板
    c.Start()
    select {} // 阻止主goroutine退出
}

完整代码

package main

import (
 "bufio"
 "crypto/tls"
 "fmt"
 gomail "gopkg.in/gomail.v2"
 "log"
 "os"
 "strings"
 "time"
)

func sendEmail(subject, body string) {
 from := "linwu.hi@gmail.com"
 pass := "lbqhjuvomebvwtox"
 to := "linwu.hi@gmail.com"

 m := gomail.NewMessage()
 m.SetHeader("From", from)
 m.SetHeader("To", to)
 m.SetHeader("Subject", subject)
 m.SetBody("text/plain", body)

 d := gomail.NewDialer("smtp.gmail.com", 587, from, pass)

 // Send the email
 if err := d.DialAndSend(m); err != nil {
  log.Fatal(err)
 }
}

func checkCertificates() {
 file, err := os.Open("domain.txt")
 if err != nil {
  panic(err)
 }
 defer file.Close()

 scanner := bufio.NewScanner(file)
 for scanner.Scan() {
  line := scanner.Text()
  parts := strings.Split(line, ":")
  domain := parts[0]
  ipPool := strings.Split(strings.ReplaceAll(parts[1], ",", " "), " ")
  // ipPool [43.138.235.240]
  fmt.Println("ipPool", ipPool)
  for _, ip := range ipPool {
   conn, err := tls.Dial("tcp", ip+":443", &amp;tls.Config{
    ServerName:         domain,
    InsecureSkipVerify: true, // We're only checking expiration, not validity
   })
   if err != nil {
    fmt.Printf("Error! %s\n", ip)
    fmt.Println(domain)
    continue
   }
   defer conn.Close()

   cert := conn.ConnectionState().PeerCertificates[0]
   endDate := cert.NotAfter
   currentTime := time.Now()
   remainingDays := endDate.Sub(currentTime).Hours() / 24

   fmt.Printf("ip: %s\ndomain: %s\n", ip, domain)

   sendEmail("SSL证书过期提醒", fmt.Sprintf("The certificate for domain %s (IP: %s) will expire in less than %f days!", domain, ip, remainingDays))
   if remainingDays < 7 &amp;&amp; remainingDays >= 0 {
    fmt.Println("剩余时间小于七天！请及时更换证书！")
    fmt.Printf("ip: %s, %s\n", ip, domain)
   } else if remainingDays < 0 {
    fmt.Println("证书已过期！请及时更换证书！")
   } else {
    fmt.Printf("剩余天数为：%f\n", remainingDays)
   }
  }
 }

 if err := scanner.Err(); err != nil {
  panic(err)
 }
}

func main() {

 c := cron.New(cron.WithSeconds())           // 创建一个新的cron实例
 c.AddFunc("0 0 0 * * ?", checkCertificates) // 每日凌晨0点执行
 c.Start()                                   // 开始执行定时任务
 select {}                                   // 阻止主goroutine退出
}