五分钟教你SSL证书自动巡检与过期提醒

柔光的暖阳◎ 2024-04-22 19:18 0阅读 0赞

<table> 
 <thead> 
  <tr> 
   <th><a href="https://www.coding-time.cn" rel="nofollow">点击在线阅读，体验更好</a></th> 
   <th><a href="https://www.coding-time.cn" rel="nofollow">链接</a></th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td><strong><a href="https://www.coding-time.cn" rel="nofollow">现代JavaScript高级小册</a></strong></td> 
   <td><a href="https://www.coding-time.cn" rel="nofollow">链接</a></td> 
  </tr> 
  <tr> 
   <td><strong><a href="https://www.coding-time.cn" rel="nofollow">深入浅出Dart</a></strong></td> 
   <td><a href="https://www.coding-time.cn" rel="nofollow">链接</a></td> 
  </tr> 
  <tr> 
   <td><strong><a href="https://www.coding-time.cn" rel="nofollow">现代TypeScript高级小册</a></strong></td> 
   <td><a href="https://www.coding-time.cn" rel="nofollow">链接</a></td> 
  </tr> 
  <tr> 
   <td><strong><a href="https://www.coding-time.cn/lc" rel="nofollow">linwu的算法笔记📒</a></strong></td> 
   <td><a href="https://www.coding-time.cn/lc" rel="nofollow">链接</a></td> 
  </tr> 
 </tbody> 
</table>

### 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候出错，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。

![image.png][]

### 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", &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 && 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", &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 && 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
    }

### 小册 ###

> 整理两本小册，一本是前端面试小册，一本是图解算法，阅读体验都很好,欢迎添加我微信`linwu-hi`获取

![image.png][image.png 1]

[image.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/22/91d0c00b0ad94f57a1dfe296e83548b7.png
[image.png 1]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/22/5824f2936aa245ec9a95890c389be5fe.png