系统日志分析_系统 服务日志分析

4案例4：系统日志分析

4.1问题

本例要求熟悉Linux系统中常见日志文件，使用必要的命令工具完成下列任务：

1. 列出所有包含关键词8909的系统日志消息
2. 查看启动时识别的鼠标设备信息
3. 列出最近2条成功/不成功的用户登录消息
4. 列出最贱10条重要程度在ERR及以上的日志消息
5. 列出所有于服务httpd相关的消息
6. 列出前4个小时内新纪录的日志

4.2方案

常见的系统日志及各自用途：

• /var/log/messages，记录内核消息、各种服务的公认消息
• /var/og/dmesg，记录系统启动过程的各种消息
• /var/log/cron，记录与cron计划任务相关的消息
• /var/log/maillog，记录邮件收发相关消息
• /var/log/secure，记录与访问限制相关的安全消息

日志消息的优先级（高-->低）：

• EMERG（紧急）：级别0，系统不可用的情况
• ALERT（警报）：级别1，必须马上采取措施的情况
• CRIT（严重）：级别2，严重情形
• ERR（错误）：级别3，出现错误
• WARNING（警告）：级别4，值得警告的情形
• NOTICE（注意）：级别5，普通但值得引起注意的事件
• INFO（信息）：级别6，一般信息
• DEBUG（调试）：级别7，程序/服务调试消息

RHEL7提供的journalctl日志工具的常见用法：

• journalctl | grep 关键词
• journalctl -u 服务名 -p 优先级
• journactl -n 消息条数
• journalctl --since="yyyy-mm-dd HH:MM:SS" --until="yyyy-mm-dd HH:MM:SS"

4.3步骤

实现此案例需要按如下步骤进行。

步骤一：分析系统日志及用户日志

1）列出所有包含关键词8909的系统日志消息

简单模拟一个故障（SELinux阻止Web开放8909端口）：

[root@svr7 ~]# vim  /etc/httpd/conf.d/8909.conf          //添加开8909端口配置
Listen 8909
[root@svr7 ~]# setenforce 1                             //开启强制模式
[root@svr7 ~]# systemctl  restart  httpd                 //起服务失败
Job for httpd.service failed because the control process exited with error code. See "systemctl status httpd.service" and "journalctl -xe" for details.

从日志文件/var/log/messages中检索信息：

[root@svr7 ~]# grep  8909  /var/log/messages 
Jan  6 17:53:48 svr7 setroubleshoot: SELinux is preventing /usr/sbin/httpd from name_bind access on the tcp_socket port 8909. For complete SELinux messages. run sealert -l 6d37b8f0-ab8a-4082-9295-c784f4f57190
Jan  6 17:53:48 svr7 python: SELinux is preventing /usr/sbin/httpd from name_bind access on the tcp_socket port 8909.#012#012*****  Plugin bind_ports (92.2 confidence) suggests   ************************#012#012If you want to allow /usr/sbin/httpd to bind to network port 8909#012Then you need to modify the port type.#012Do#012# semanage port -a -t PORT_TYPE -p tcp 8909#012    where PORT_TYPE is one of the following: http_cache_port_t, http_port_t, jboss_management_port_t, jboss_messaging_port_t, ntop_port_t, puppet_port_t.#012#012*****  Plugin catchall_boolean (7.83 confidence) suggests   ******************#012#012If you want to allow nis to enabled#012Then you must tell SELinux about this by enabling the 'nis_enabled' boolean.#012#012Do#012setsebool -P nis_enabled 1#012#012*****  Plugin catchall (1.41 confidence) suggests   **************************#012#012If you believe that httpd should be allowed name_bind access on the port 8909 tcp_socket by default.#012Then you should report this as a bug.#012You can generate a local policy module to allow this access.#012Do#012allow this access for now by executing:#012# grep httpd /var/log/audit/audit.log | audit2allow -M mypol#012# semodule -i mypol.pp#012
.. ..

使用完毕记得删除测试配置文件：

[root@svr7 ~]# rm  -rf  /etc/httpd/conf.d/8909.conf
[root@svr7 ~]# systemctl  restart  httpd

2）查看启动识别的鼠标设备信息

[root@svr7 ~]# dmesg  |  grep  -i  mouse
[    1.020385] mousedev: PS/2 mouse device common for all mice
[    1.249422] input: ImPS/2 Generic Wheel Mouse as /devices/platform/i8042/serio1/input/input2
[    2.279665] usb 2-1: Product: VMware Virtual USB Mouse
[    2.603999] input: VMware VMware Virtual USB Mouse as /devices/pci0000:00/0000:00:11.0/0000:02:00.0/usb2/2-1/2-1:1.0/input/input3
[    2.604222] hid-generic 0003:0E0F:0003.0001: input,hidraw0: USB HID v1.10 Mouse [VMware VMware Virtual USB Mouse] on usb-0000:02:00.0-1/input0

3）列出最近2条成功/不成功的用户登录消息

查看成功登录的事件消息：

[root@svr7 ~]# last  -2
zhsan    pts/2        192.168.4.207    Fri Jan  6 18:00 - 18:00  (00:00)    
root     pts/2        192.168.4.110    Fri Jan  6 17:26 - 17:59  (00:33)    
wtmp begins Thu Aug  4 00:10:16 2016

查看失败登录的事件消息： 

[root@svr7 ~]# lastb  -2
anonymou ssh:notty    192.168.4.207    Fri Jan  6 18:00 - 18:00  (00:00)    
anonymou ssh:notty    192.168.4.207    Fri Jan  6 18:00 - 18:00  (00:00)    
btmp begins Fri Jan  6 18:00:34 2017

步骤二：使用journalctl日志提取工具

1）列出最近10条重要程度在ERR及以上的日志消息

[root@svr7 ~]# journalctl  -p err  -n  10
-- Logs begin at Thu 2017-01-05 15:50:08 CST, end at Fri 2017-01-06 18:01:01 CST. --
Jan 06 14:56:57 svr7 setroubleshoot[23702]: SELinux is preventing /usr/sbin/vsftpd from getattr access on the file /rhel7/repodata/repomd.xml. For complete SELinux mes
Jan 06 14:56:57 svr7 setroubleshoot[23702]: SELinux is preventing /usr/sbin/vsftpd from read access on the file repomd.xml. For complete SELinux messages. run sealert 
Jan 06 14:56:57 svr7 setroubleshoot[23702]: SELinux is preventing /usr/sbin/vsftpd from read access on the file repomd.xml. For complete SELinux messages. run sealert 
Jan 06 14:56:57 svr7 setroubleshoot[23702]: SELinux is preventing /usr/sbin/vsftpd from lock access on the file /rhel7/repodata/repomd.xml. For complete SELinux messag
Jan 06 17:53:48 svr7 setroubleshoot[33743]: Plugin Exception restorecon_source
Jan 06 17:53:48 svr7 setroubleshoot[33743]: SELinux is preventing /usr/sbin/httpd from name_bind access on the tcp_socket port 8909. For complete SELinux messages. run
Jan 06 17:53:53 svr7 setroubleshoot[33743]: SELinux is preventing /usr/sbin/httpd from name_connect access on the tcp_socket port 8909. For complete SELinux messages. 
Jan 06 17:53:54 svr7 systemd[1]: Failed to start The Apache HTTP Server.
.. ..
lines 1-11/11 (END)

2）列出所有与服务httpd相关的消息

[root@svr7 ~]# journalctl   -u  httpd
-- Logs begin at Thu 2017-01-05 15:50:08 CST, end at Fri 2017-01-06 18:01:01 CST. --
Jan 06 14:57:16 svr7 systemd[1]: Starting The Apache HTTP Server...
Jan 06 14:57:16 svr7 httpd[23812]: AH00557: httpd: apr_sockaddr_info_get() failed for svr7
Jan 06 14:57:16 svr7 httpd[23812]: AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 127.0.0.1. Set the 'ServerName' directi
Jan 06 14:57:16 svr7 systemd[1]: Started The Apache HTTP Server.
Jan 06 17:53:44 svr7 systemd[1]: Stopping The Apache HTTP Server...
Jan 06 17:53:46 svr7 systemd[1]: Starting The Apache HTTP Server...
Jan 06 17:53:46 svr7 httpd[33741]: AH00557: httpd: apr_sockaddr_info_get() failed for svr7
.. ..

 3）列出前4个小时内新记录的日志

根据当前日期时间往前推4个小时，确定--since起始和--until结束时刻：

[root@svr7 ~]# journalctl  --since  "2017-01-06 14:11"  --until  "2017-01-06 18:11"
-- Logs begin at Thu 2017-01-05 15:50:08 CST, end at Fri 2017-01-06 18:10:01 CST. --
Jan 06 14:20:01 svr7 systemd[1]: Started Session 160 of user root.
Jan 06 14:20:01 svr7 CROND[22869]: (root) CMD (/usr/lib64/sa/sa1 1 1)
Jan 06 14:20:01 svr7 systemd[1]: Starting Session 160 of user root.
Jan 06 14:30:01 svr7 systemd[1]: Started Session 161 of user root.
Jan 06 14:30:01 svr7 CROND[23028]: (root) CMD (/usr/lib64/sa/sa1 1 1)
Jan 06 14:31:39 svr7 systemd[1]: Starting Session 162 of user root.
Jan 06 14:32:17 svr7 sshd[23046]: pam_unix(sshd:session): session closed for user root
Jan 06 14:31:39 svr7 systemd[1]: Started Session 162 of user root.
Jan 06 14:31:39 svr7 sshd[23046]: pam_unix(sshd:session): session opened for user root by (uid=0)
Jan 06 14:31:39 svr7 systemd-logind[985]: New session 162 of user root.
.. .