（一）Rsyslog简介
ryslog 是一个快速处理收集系统日志的程序，提供了高性能、安全功能和模块化设计。rsyslog 是syslog 的升级版，它将多种来源输入输出转换结果到目的地。
rsyslog是一个开源工具，被广泛用于Linux系统以通过TCP/UDP协议转发或接收日志消息。rsyslog守护进程可以被配置成两种环境，一种是配置成日志收集服务器，rsyslog进程可以从网络中收集其它主机上的日志数据，这些主机会将日志配置为发送到另外的远程服务器。rsyslog的另外一个用法，就是可以配置为客户端，用来过滤和发送内部日志消息到本地文件夹（如/var/log）或一台可以路由到的远程rsyslog服务器上。
logrotate是一个日志文件管理工具。用来把旧文件轮转、压缩、删除，并且创建新的日志文件。我们可以根据日志文件的大小、天数等来转储，便于对日志文件管理，一般都是通过cron计划任务来完成的。
| 序号 | IP地址 | 类型 | 备注 |
|---|---|---|---|
| 1 | 192.168.99.99 | Server端 | |
| 2 | 192.168.99.98 | client端 |
（二）rsyslog server服务端配置
1，rsyslog默认是安装的，如果没有安装通过 [[email protected] samba]# yum install rsyslog -y
2，修改/etc/rsyslog.conf配置文件，启用udp和tcp模块 $ModLoad imudp $UDPServerRun 514 $ModLoad imtcp
$InputTCPServerRun 514
[[email protected] samba]# vim /etc/rsyslog.conf
$ModLoad imuxsock # provides support for local system logging (e.g. via logger command)
$ModLoad imjournal # provides access to the systemd journal
#####开启udp接收日志
$ModLoad imudp
$UDPServerRun 514
$template RemoteHost,"/data/syslog/%$YEAR%-%$MONTH%-%$DAY%/%FROMHOST-IP%.log"
*.* ?RemoteHost
& ~
####开启tcp协议接受日志
$ModLoad imtcp
$InputTCPServerRun 514
$WorkDirectory /var/lib/rsyslog
$ActionFileDefaultTemplate RSYSLOG_TraditionalFileFormat
#######启用/etc/rsyslog.d/*.conf目录下所有以.conf结尾的配置文件
$IncludeConfig /etc/rsyslog.d/*.conf
$OmitLocalLogging on
$IMJournalStateFile imjournal.state
*.info;mail.none;authpriv.none;cron.none /var/log/messages
authpriv.* /var/log/secure
mail.* -/var/log/maillog
cron.* /var/log/cron
*.emerg :omusrmsg:*
uucp,news.crit /var/log/spooler
local7.* /var/log/boot.log
local0.* /etc/keepalived/keepalived.log3,重启rsyslog服务
[[email protected] 2018-05-23]# systemctl restart rsyslog
[[email protected] 2018-05-23]# systemctl status rsyslog
[[email protected] samba]# netstat -anp|grep 514
tcp 0 0 0.0.0.0:514 0.0.0.0:* LISTEN 1445/rsyslogd
tcp6 0 0 :::514 :::* LISTEN 1445/rsyslogd
udp 0 0 0.0.0.0:514 0.0.0.0:* 1445/rsyslogd
udp6 0 0 :::514 :::* 1445/rsyslogd （三）rsyslog客户端的配置
1，编辑rsylog客户端的配置文件：
[[email protected] log]# grep -v "^$" /etc/rsyslog.conf | grep -v "^#"
$ModLoad imuxsock # provides support for local system logging (e.g. via logger command)
$ModLoad imjournal # provides access to the systemd journal
$WorkDirectory /var/lib/rsyslog
$ActionFileDefaultTemplate RSYSLOG_TraditionalFileFormat
$template myFormat,"%timestamp% %fromhost-ip% %msg%\n" #######自定义模板的相关信息
$IncludeConfig /etc/rsyslog.d/*.conf
$OmitLocalLogging on
$IMJournalStateFile imjournal.state
*.* @192.168.99.99:514 ########该声明告诉rsyslog守护进程，将系统上各个设备的各种日志的所有消息路由到远程rsyslog服务器（192.168.99.99）的UDP端口514。@@是通过tcp传输，一个@是通过udp传输。
*.info;mail.none;authpriv.none;cron.none /var/log/messages
authpriv.* /var/log/secure
mail.* -/var/log/maillog
cron.* /var/log/cron
*.emerg :omusrmsg:*
uucp,news.crit /var/log/spooler
local7.* /var/log/boot.log
local0.* /etc/keepalived/keepalived.log2，重启客户端rsyslog服务
[[email protected] log]# systemctl restart rsyslog
[[email protected] log]# systemctl status rsyslog
● rsyslog.service - System Logging Service
Loaded: loaded (/usr/lib/systemd/system/rsyslog.service; enabled; vendor preset: enabled)
Active: active (running) since 四 2018-05-24 16:57:04 CST; 4s ago
Main PID: 44765 (rsyslogd)
CGroup: /system.slice/rsyslog.service
└─44765 /usr/sbin/rsyslogd -n
5月 24 16:57:04 server98 systemd[1]: Starting System Logging Service...
5月 24 16:57:04 server98 systemd[1]: Started System Logging Service.（四）查看客户端和服务端的日志是否正常生成。
（1）查看服务端是否在/data/日期/ip.log正常生成。
[[email protected] 2018-05-24]# tail -f /data/2018-05-24/192.168.99.98.log
2018-05-24T17:02:52+08:00 server98 postfix/pickup[41198]: AAC764ACB03: uid=0 from=<[email protected]>
2018-05-24T17:02:52+08:00 server98 postfix/cleanup[45967]: AAC764ACB03: message-id=<[email protected]>
2018-05-24T17:02:52+08:00 server98 postfix/qmgr[2356]: AAC764ACB03: from=<[email protected]>, size=851, nrcpt=1 (queue active)
2018-05-24T17:02:52+08:00 server98 postfix/smtp[39596]: AAC764ACB03: to=<[email protected]>, relay=none, delay=0, delays=0/0/0/0, dsn=5.4.4, status=bounced (Host or domain name not found. Name service error for name=address.somewhere type=AAAA: Host not found)
2018-05-24T17:02:52+08:00 server98 postfix/cleanup[45967]: AB6804ACB0B: message-id=<[email protected]>
2018-05-24T17:02:52+08:00 server98 postfix/bounce[45968]: AAC764ACB03: sender non-delivery notification: AB6804ACB0B
2018-05-24T17:02:52+08:00 server98 postfix/qmgr[2356]: AB6804ACB0B: from=<>, size=2811, nrcpt=1 (queue active)
2018-05-24T17:02:52+08:00 server98 postfix/qmgr[2356]: AAC764ACB03: removed
2018-05-24T17:02:52+08:00 server98 postfix/smtp[39597]: AB6804ACB0B: to=<[email protected]>, relay=none, delay=0, delays=0/0/0/0, dsn=5.4.4, status=bounced (Host or domain name not found. Name service error for name=company.xy type=AAAA: Host not found)
2018-05-24T17:02:52+08:00 server98 postfix/qmgr[2356]: AB6804ACB0B: removed
2018-05-24T17:14:33+08:00 server98 root: hello world（2）在客户端生成日志，是否日志同步，都有
[[email protected] ~]# tail -f /var/log/messages
May 24 17:11:40 server98 Keepalived_vrrp[49377]: VRRP_Script(chk_http_port) succeeded
May 24 17:11:52 server98 smokeping[38532]: Alert someloss is active for Other.hefei.hefei-office2
May 24 17:11:52 server98 smokeping[38532]: Alert someloss is active for Other.wuxi.wuxi-office2
May 24 17:12:52 server98 smokeping[38532]: Alert someloss is active for Other.hefei.hefei-office2
May 24 17:12:52 server98 smokeping[38532]: Alert someloss is active for Other.wuxi.wuxi-office2
May 24 17:13:52 server98 smokeping[38532]: Alert someloss is active for Other.hefei.hefei-office2
May 24 17:13:52 server98 smokeping[38532]: Alert someloss is active for Other.wuxi.wuxi-office2
May 24 17:14:33 server98 root: hello world
至此，日志服务端和客户端日志同步完成。
备注：
1，Facility是syslog的模块: rsyslog通过facility概念来定义日志消息的来源，以方便对日志进行分类。Facility:有0-23种设备可选，在python的syslog库中有一部分缺失
0 kernel messages
1 user-level messages
2 mail system
3 system daemons
4 security/authorization messages
5 messages generated internally by syslogd
6 line printer subsystem
7 network news subsystem
8 UUCP subsystem
9 clock daemon
10 security/authorization messages
11 FTP daemon
12 NTP subsystem
13 log audit
14 log alert
15 clock daemon
16-23 local0 - local7
常用的有：
2，Severity:日志等级
0 Emergency
1 Alert
2 Critical
3 Error
4 Warning
5 Notice
6 Informational
7 Debug
重要的配置文件：
1，rsyslog server服务端的配置：
[[email protected] 2018-05-23]# grep -v "^$" /etc/rsyslog.conf | grep -v "^#"
$ModLoad imuxsock # provides support for local system logging (e.g. via logger command)
$ModLoad imjournal # provides access to the systemd journal
$ModLoad imudp
$UDPServerRun 514
$template RemoteHost,"/data/%$YEAR%-%$MONTH%-%$DAY%/%FROMHOST-IP%.log"
*.* ?RemoteHost
& ~
$ModLoad imtcp
$InputTCPServerRun 514
$WorkDirectory /var/lib/rsyslog
$ActionFileDefaultTemplate RSYSLOG_TraditionalFileFormat
$IncludeConfig /etc/rsyslog.d/*.conf
$OmitLocalLogging on
$IMJournalStateFile imjournal.state
*.info;mail.none;authpriv.none;cron.none /var/log/messages
authpriv.* /var/log/secure
mail.* -/var/log/maillog
cron.* /var/log/cron
*.emerg :omusrmsg:*
uucp,news.crit /var/log/spooler
local7.* /var/log/boot.log
local0.* /etc/keepalived/keepalived.log
2，rsyslog 客户端的配置
[[email protected] log]# grep -v "^$" /etc/rsyslog.conf | grep -v "^#"
$ModLoad imuxsock # provides support for local system logging (e.g. via logger command)
$ModLoad imjournal # provides access to the systemd journal
$WorkDirectory /var/lib/rsyslog
$ActionFileDefaultTemplate RSYSLOG_TraditionalFileFormat
$template myFormat,"%timestamp% %fromhost-ip% %msg%\n"
$IncludeConfig /etc/rsyslog.d/*.conf
$OmitLocalLogging on
$IMJournalStateFile imjournal.state
*.info;mail.none;authpriv.none;cron.none @192.168.99.99:514
*.info;mail.none;authpriv.none;cron.none /var/log/messages
authpriv.* /var/log/secure
mail.* -/var/log/maillog
cron.* /var/log/cron
*.emerg :omusrmsg:*
uucp,news.crit /var/log/spooler
local7.* /var/log/boot.log
local0.* /etc/keepalived/keepalived.log原文地址：http://blog.51cto.com/liqingbiao/2119953