rsyslog 可以理解为多线程增强版的syslog。 在syslog的基础上扩展了很多其他功能，如数据库支持（MySQL、PostgreSQL、Oracle等）、日志内容筛选、定义日志格式模板等。目前大多数Linux发行版默认也是使用rsyslog进行日志记录。rsyslog提供了三种远程传输协议：

rsyslog的简单配置记录（如下将公司防火墙上的日志（UDP）打到IDC的rsyslog日志服务器上）

====================再看一例=======================
以上配置的是将公司防火墙的日志打到rsyslog里。现在有这么一个需求：
公司IDC的另外两台服务器172.19.10.24和172.19.10.25上部署了gitlab、nexus、jenkins、jira和wiki，上面的权限设置的比较杂，很多人都有登录需求。现在需要将登录到这两台服务器上的用户的所有操作过程记录下来，记录达到rsyslog日志里，相当于做用户操作记录的审计工作。

=====================通过rsyslog收集nginx日志到远程服务器上====================
需求说明：通过rsyslog服务将192.168.10.21服务器上的/data/nginx/logs/www.kevin.com-access.log日志实时同步到192.168.10.52服务器上（路径为/data/rsyslog/nginx）。

1）192.168.10.21为rsyslog客户端，即日志的推送端。rsyslog日志是客户机主动将自己的日志推送到远程服务器上。
操作如下：
[root@nginx-server ~]# yum install rsyslog -y
[root@nginx-server ~]# cp /etc/rsyslog.conf /etc/rsyslog.conf.bak
[root@nginx-server ~]# cat /etc/rsyslog.conf
# rsyslog v5 configuration file

# For more information see /usr/share/doc/rsyslog-*/rsyslog_conf.html
# If you experience problems, see http://www.rsyslog.com/doc/troubleshoot.html

#### MODULES ####

$ModLoad imuxsock # provides support for local system logging (e.g. via logger command)
$ModLoad imklog # provides kernel logging support (previously done by rklogd)
#$ModLoad immark # provides --MARK-- message capability
$ModLoad imfile                               ##装载imfile模块，这一行手动添加

# Provides UDP syslog reception
#$ModLoad imudp
#$UDPServerRun 514

# Provides TCP syslog reception
#$ModLoad imtcp
#$InputTCPServerRun 514

#### GLOBAL DIRECTIVES ####

# Use default timestamp format
$ActionFileDefaultTemplate RSYSLOG_TraditionalFileFormat

# File syncing capability is disabled by default. This feature is usually not required,
# not useful and an extreme performance hit
#$ActionFileEnableSync on

# Include all config files in /etc/rsyslog.d/
$IncludeConfig /etc/rsyslog.d/*.conf

#### RULES ####

# Log all kernel messages to the console.
# Logging much else clutters up the screen.
#kern.* /dev/console

# Log anything (except mail) of level info or higher.
# Don‘t log private authentication messages!
*.info;mail.none;authpriv.none;cron.none;local5.none /var/log/messages             ##不记录local5的日志

# The authpriv file has restricted access.
authpriv.* /var/log/secure

# Log all the mail messages in one place.
mail.* -/var/log/maillog

# Log cron stuff
cron.* /var/log/cron

# Everybody gets emergency messages
*.emerg *

# Save news errors of level crit and higher in a special file.
uucp,news.crit /var/log/spooler

# Save boot messages also to boot.log
local7.* /var/log/boot.log

# ### begin forwarding rule ###
# The statement between the begin ... end define a SINGLE forwarding
# rule. They belong together, do NOT split them. If you create multiple
# forwarding rules, duplicate the whole block!
# Remote Logging (we use TCP for reliable delivery)
#
# An on-disk queue is created for this action. If the remote host is
# down, messages are spooled to disk and sent when it is up again.
#$WorkDirectory /var/lib/rsyslog # where to place spool files
#$ActionQueueFileName fwdRule1 # unique name prefix for spool files
#$ActionQueueMaxDiskSpace 1g # 1gb space limit (use as much as possible)
#$ActionQueueSaveOnShutdown on # save messages to disk on shutdown
#$ActionQueueType LinkedList # run asynchronously
#$ActionResumeRetryCount -1 # infinite retries if host is down
# remote host is: name/ip:port, e.g. 192.168.0.1:514, port optional
#*.* @@remote-host:514
# ### end of the forwarding rule ###
user.info /var/log/history

#在文件底部添加下面几行内容
$InputFileName /data/nginx/logs/www.kevin.com-access.log        ##读取日志文件（要监控的日志文件）
$InputFileTag web_access             ##日志写入日志附加标签字符串
$InputFileSeverity info           ##日志等级
$InputFileStateFile /etc/rsyslog.d/stat-access         ##记录日志点等信息。(相当于msyql的master.info)文件名变了，
这个StateFile标志必须变，否则无法传输。
$InputFileFacility local5         ##设施类别
$InputFilePollInterval 1          ##检查日志文件间隔（秒）
$InputFilePersistStateInterval 1       ##回写偏移量数据到文件间隔时间（秒）
$InputRunFileMonitor                          ##激活读取，可以设置多组日志读取，每组结束时设置本参数。以示生效。
local5.* @192.168.10.52            ##代表local5设施的所有级别通过udp协议传送到192.168.10.51

重启rsyslog服务
[root@nginx-server ~]# /etc/init.d/rsyslog restart
关闭系统日志记录器： [确定]
启动系统日志记录器： [确定]

由于作为日志的推送端，rsyslog日志不需要开启514端口（如上在rsyslog.conf文件里没有打开dup或tcp的514端口）
[root@nginx-server ~]# lsof -i:514
[root@nginx-server ~]#

2）192.168.10.52为rsyslog服务端，即日志的接收端。
配置如下：
[root@log-server ~]# yum install rsyslog -y
[root@log-server ~]# cp /etc/rsyslog.conf /etc/rsyslog.conf.bak
# rsyslog configuration file

# For more information see /usr/share/doc/rsyslog-*/rsyslog_conf.html
# If you experience problems, see http://www.rsyslog.com/doc/troubleshoot.html

#### MODULES ####

# The imjournal module bellow is now used as a message source instead of imuxsock.
$ModLoad imuxsock # provides support for local system logging (e.g. via logger command)
$ModLoad imjournal # provides access to the systemd journal
#$ModLoad imklog # reads kernel messages (the same are read from journald)
#$ModLoad immark # provides --MARK-- message capability

# Provides UDP syslog reception
$ModLoad imudp                   ##载入imudp模块
$UDPServerRun 514            ##开启udp接收并制定端口号

# Provides TCP syslog reception
$ModLoad imtcp                 ##载入imtcp模块。
$InputTCPServerRun 514             ##开启tcp接收并制定端口号。tcp和udp两个端口模块可以同时使用！

#### GLOBAL DIRECTIVES ####

# Where to place auxiliary files
$WorkDirectory /var/lib/rsyslog

# Use default timestamp format
$ActionFileDefaultTemplate RSYSLOG_TraditionalFileFormat

#定义一个模板用来指定接收的日志消息的格式（默认会在记录的日志前加几个字段）
$template  SpiceTmpl,"%msg%\n"                   ##%msg:2:$%为去掉日志开头的空格

#定义一个模板用来指定接收的日志文件的存放路径%……%之间的是定义日志按照年-月-日命名
$template  DynaFile,"/data/rsyslog/nginx/%$YEAR%-%$MONTH%-%$DAY%.log"

# File syncing capability is disabled by default. This feature is usually not required,
# not useful and an extreme performance hit
#$ActionFileEnableSync on

# Include all config files in /etc/rsyslog.d/
$IncludeConfig /etc/rsyslog.d/*.conf

# Turn off message reception via local log socket;
# local messages are retrieved through imjournal now.
$OmitLocalLogging on

# File to store the position in the journal
$IMJournalStateFile imjournal.state

#### RULES ####

# Log all kernel messages to the console.
# Logging much else clutters up the screen.
#kern.* /dev/console

# Log anything (except mail) of level info or higher.
# Don‘t log private authentication messages!
*.info;mail.none;authpriv.none;cron.none;local5.none                /var/log/messages            ##不记录local5设施的日志

# The authpriv file has restricted access.
authpriv.* /var/log/secure

# Log all the mail messages in one place.
mail.* -/var/log/maillog

# Log cron stuff
cron.* /var/log/cron

# Everybody gets emergency messages
*.emerg :omusrmsg:*

# Save news errors of level crit and higher in a special file.
uucp,news.crit /var/log/spooler

# Save boot messages also to boot.log
local7.* /var/log/boot.log

#接收客户端local5设施传送来的日志并存放到指定位置（位置可用定义的模板。?代表使用动态的模板）
local5.*                       ?DynaFile;SpiceTmpl

# ### begin forwarding rule ###
# The statement between the begin ... end define a SINGLE forwarding
# rule. They belong together, do NOT split them. If you create multiple
# forwarding rules, duplicate the whole block!
# Remote Logging (we use TCP for reliable delivery)
#
# An on-disk queue is created for this action. If the remote host is
# down, messages are spooled to disk and sent when it is up again.
#$ActionQueueFileName fwdRule1 # unique name prefix for spool files
#$ActionQueueMaxDiskSpace 1g # 1gb space limit (use as much as possible)
#$ActionQueueSaveOnShutdown on # save messages to disk on shutdown
#$ActionQueueType LinkedList # run asynchronously
#$ActionResumeRetryCount -1 # infinite retries if host is down
# remote host is: name/ip:port, e.g. 192.168.0.1:514, port optional
#*.* @@remote-host:514
# ### end of the forwarding rule ###

编辑/etc/sysconfig/rsyslog中"SYSLOGD_OPTIONS="开启远程日志接收功能
[root@log-server ~]# cat /etc/sysconfig/rsyslog
# Options for rsyslogd
# Syslogd options are deprecated since rsyslog v3.
# If you want to use them, switch to compatibility mode 2 by "-c 2"
# See rsyslogd(8) for more details
SYSLOGD_OPTIONS="-c 5"

创建日志接收过来后定义的存放目录
[root@log-server ~]# mkdir -p /data/rsyslog/nginx

重启rsyslog服务
[root@log-server ~]# /etc/init.d/rsyslog restart
Shutting down system logger: [ OK ]
Starting system logger: [ OK ]
[root@log-server ~]# lsof -i:514
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
rsyslogd 24594 root 2u IPv4 38927639 0t0 TCP *:shell (LISTEN)
rsyslogd 24594 root 3u IPv4 38927635 0t0 UDP *:syslog
rsyslogd 24594 root 4u IPv6 38927636 0t0 UDP *:syslog
rsyslogd 24594 root 5u IPv6 38927640 0t0 TCP *:shell (LISTEN)

查看日志是否接收过来了
[root@log-server ~]# ll /data/rsyslog/nginx/
total 550876
-rw------- 1 root root 483539594 Jun 13 12:58 2018-06-13.log
[root@log-server ~]# tail -2 /data/rsyslog/nginx/2018-06-13.log
1.203.163.198 - [27/Apr/2018:00:17:53 +0800] "POST /scf/%7B%7BloginConfig.loginSubmitUrl%7D%7D HTTP/1.1" 302 0 "https://www.kevin.com/scf/login" Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/29.0.1547.62 Safari/537.36 - 0.010 0.003 10.0.54.21:9020 302
1.203.163.198 - [27/Apr/2018:00:17:53 +0800] "POST /scf/%7B%7BloginConfig.loginSubmitUrl%7D%7D HTTP/1.1" 302 0 "https://www.kevin.com/scf/login" Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/29.0.1547.62 Safari/537.36 - 0.012 0.003 10.0.54.21:9020 302

=========================温馨提示========================
rsyslog也可以收集多个日志文件，需要注意的是：
$InputFileTag        定义的APPNAME必须唯一，同一台主机上不同的应用应当使用不同的APPNAME，否则会导致新定义的TOKEN和TAG不生效；
$template         定义的模板名必须唯一，否则会导致新定义的TOKEN和TAG不生效；
$InputFileStateFile       定义的StateFile必须唯一，它被rsyslog用于记录文件上传进度，否则会导致混乱；

如下是rsyslog收集多个日志的配置，这里以2个日志文件为例：

日志的推送端配置

日志的接收端配置

==========================================================================
注意：
a）如果发现日志还没有接收过来，即/data/rsyslog/nginx目录下没有日志产生，就同时重启推送端和接收端的rsyslog服务。确保双方的iptables防火墙和selinux关闭！
b）也可以自行修改接收的日志文件的存放路径，如改为下面的配置：
$template DynaFile,"/data/rsyslog/nginx/nginx-access.log"
则日志收集后存放的文件如下：
[root@log-server ~]# ll /data/rsyslog/nginx/
total 571716
-rw------- 1 root root 483539594 Jun 13 12:58 2018-06-13.log
-rw------- 1 root root 101893593 Jun 13 13:13 nginx-access.log

Linux下rsyslog日志收集服务环境部署记录