动态分析maillog日志，把恶意链接直接用防火墙禁止

            最近用 postfix + dovecot 搭建了一个邮件服务器， 被人当做垃圾邮件转发器，经过配置postfix 的黑白名单， postfix 提示成功的 REJECT 了垃圾邮件， 不过还是有无数的IP地址， 连接过来要进行发送邮件， 虽然垃圾邮件被拒绝了，但是未知连接太多，造成 maillog 日志越变越大， 拖慢 postfix 的运行速度，  总得想个办法解决。要是能把这些无用的IP地址直接用防火墙拒绝就好了。 思路有了，我们就着手处理吧。

这些垃圾IP地址全部是

• 本站主数据：台湾省 中华电信股份有限公司
• 参考数据一：台湾

tail    -f    /var/log/maillog   查看日志如下所示：

这日志还是很有规律的， 是不是 ？

Aug 20 12:11:40 www postfix/smtpd[18033]: NOQUEUE: reject: RCPT from 36-224-133-61.dynamic-ip.hinet.net[36.224.133.61]: 554 5.7.1 <[email protected]>: Recipient address rejected: Access denied; from=<[email protected]> to=<[email protected]> proto=SMTP helo=<115.28.81.191>
Aug 20 12:11:41 www postfix/smtpd[18033]: NOQUEUE: reject: RCPT from 36-224-133-61.dynamic-ip.hinet.net[36.224.133.61]: 554 5.7.1 <[email protected]>: Recipient address rejected: Access denied; from=<[email protected]> to=<[email protected]> proto=SMTP helo=<115.28.81.191>
Aug 20 12:11:41 www postfix/smtpd[18026]: NOQUEUE: reject: RCPT from 36-224-135-60.dynamic-ip.hinet.net[36.224.135.60]: 554 5.7.1 <[email protected]>: Recipient address rejected: Access denied; from=<[email protected]> to=<[email protected]> proto=SMTP helo=<115.28.81.191>
Aug 20 12:11:42 www postfix/smtpd[18023]: NOQUEUE: reject: RCPT from 114-45-29-112.dynamic.hinet.net[114.45.29.112]: 554 5.1.8 <[email protected]>: Sender address rejected: Domain not found; from=<[email protected]> to=<[email protected]> proto=SMTP helo=<115.28.81.191>
Aug 20 12:11:43 www postfix/smtpd[18033]: NOQUEUE: reject: RCPT from 36-224-133-61.dynamic-ip.hinet.net[36.224.133.61]: 554 5.7.1 <[email protected]>: Recipient address rejected: Access denied; from=<[email protected]> to=<[email protected]> proto=SMTP helo=<115.28.81.191>
Aug 20 12:11:43 www postfix/smtpd[18026]: NOQUEUE: reject: RCPT from 36-224-135-60.dynamic-ip.hinet.net[36.224.135.60]: 554 5.7.1 <[email protected]>: Recipient address rejected: Access denied; from=<[email protected]> to=<[email protected]> proto=SMTP helo=<115.28.81.191>
Aug 20 12:11:44 www postfix/smtpd[18033]: NOQUEUE: reject: RCPT from 36-224-133-61.dynamic-ip.hinet.net[36.224.133.61]: 554 5.7.1 <[email protected]>: Recipient address rejected: Access denied; from=<[email protected]> to=<[email protected]> proto=SMTP helo=<115.28.81.191>
Aug 20 12:11:44 www postfix/smtpd[18023]: NOQUEUE: reject: RCPT from 114-45-29-112.dynamic.hinet.net[114.45.29.112]: 554 5.1.8 <[email protected]>: Sender address rejected: Domain not found; from=<[email protected]> to=<[email protected]> proto=SMTP helo=<115.28.81.191>
Aug 20 12:11:45 www postfix/smtpd[18033]: NOQUEUE: reject: RCPT from 36-224-133-61.dynamic-ip.hinet.net[36.224.133.61]: 554 5.7.1 <[email protected]>: Recipient address rejected: Access denied; from=<[email protected]> to=<[email protected]> proto=SMTP helo=<115.28.81.191>
Aug 20 12:11:45 www postfix/smtpd[18026]: too many errors after RCPT from 36-224-135-60.dynamic-ip.hinet.net[36.224.135.60]
Aug 20 12:11:45 www postfix/smtpd[18026]: disconnect from 36-224-135-60.dynamic-ip.hinet.net[36.224.135.60]
Aug 20 12:11:46 www postfix/smtpd[18023]: too many errors after RCPT from 114-45-29-112.dynamic.hinet.net[114.45.29.112]
Aug 20 12:11:46 www postfix/smtpd[18023]: disconnect from 114-45-29-112.dynamic.hinet.net[114.45.29.112]
Aug 20 12:11:47 www postfix/smtpd[18033]: NOQUEUE: reject: RCPT from 36-224-133-61.dynamic-ip.hinet.net[36.224.133.61]: 554 5.7.1 <[email protected]>: Recipient address rejected: Access denied; from=<[email protected]> to=<[email protected]> proto=SMTP helo=<115.28.81.191>
Aug 20 12:11:49 www postfix/smtpd[18033]: too many errors after RCPT from 36-224-133-61.dynamic-ip.hinet.net[36.224.133.61]
Aug 20 12:11:49 www postfix/smtpd[18033]: disconnect from 36-224-133-61.dynamic-ip.hinet.net[36.224.133.61]
Aug 20 12:14:10 www postfix/smtpd[18097]: connect from 36-224-136-82.dynamic-ip.hinet.net[36.224.136.82]
Aug 20 12:14:11 www postfix/smtpd[18097]: NOQUEUE: reject: RCPT from 36-224-136-82.dynamic-ip.hinet.net[36.224.136.82]: 554 5.7.1 <[email protected]>: Sender address rejected: Access denied; from=<[email protected]> to=<[email protected]> proto=SMTP helo=<115.28.81.191>
Aug 20 12:14:11 www postfix/smtpd[18097]: NOQUEUE: reject: RCPT from 36-224-136-82.dynamic-ip.hinet.net[36.224.136.82]: 554 5.7.1 <[email protected]>: Sender address rejected: Access denied; from=<[email protected]> to=<[email protected]> proto=SMTP helo=<115.28.81.191>

我们可以动态分析日志， 把  

too many errors after RCPT from
后面的IP地址获取， 动态加入到防火墙进行拒绝就行。

思路有了， 我就写个小程序来分析日志吧，我写的是C的，  不过用perl 或者 shell 脚本可能更简单。

反正用自己最熟悉的语言就行。 

dyn.c 源代码文件的内容如下 ：

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#define BUF_LEN   4096
#define DATA_LEN  4096*10

int  main (int argc, char** argv)
{
    //too many errors after RCPT from 36-224-128-99.dynamic-ip.hinet.net[36.224.128.99]
    //too many errors after RCPT from 118-169-22-28.dynamic.hinet.net[118.169.22.28]
    //too many errors after AUTH from unknown[79.125.161.236]

        char buf[BUF_LEN] = {0};
    const char* sep = "too many errors after";
    
    while (1)
    {
        memset (buf, 0, sizeof(buf));
        char* tp = fgets (buf, sizeof(buf)-1, stdin);
        if (tp != NULL)
        {
            int buflen = strlen(tp);
            char* p = strstr(buf, sep);
            if (p != NULL)
            {
                char* p1 = p + strlen(sep) + 1;
                char* ps = NULL;
                char* pe = NULL;
                while (*p1 != '\0' && *p1 != '\n')
                {
                    if (*p1 == '[')
                        ps = p1+1;
                    if (*p1 == ']')
                        pe = p1;
                    p1++;
                }
                
                if (ps != NULL && pe != NULL)
                {
                    char ipbuf[64]={0};
                    memcpy (ipbuf, ps, pe-ps);
                    char ebuf[512] = {0};
                    snprintf(ebuf, sizeof(ebuf)-1, "iptables -I INPUT -s %s -j DROP", ipbuf);
                    system (ebuf);
                    printf ("%s\n", ebuf);
                }

            }
        }

    }
    
    return 0;
}

用  gcc   -g -o dyn  dyn.c    ， 编译后生成了可执行文件   dyn

我的dyn可执行文件在  /root 目录， 所以用 命令：

nohup   tail  -f   /var/log/maillog  |  /root/dyn  &

让它自己跑吧。

过一段时间后， 我们再看maillog日志，  已经基本没有 不认识的IP地址再连接过来打算发邮件了。