说明：
nagios监控系统的报警功能确实不错，经常半夜被那邮件告警给叫起来 – -，也不知道是好是坏。如果配合cacti，图像显示功能，这监控系统就很好了。当然这篇，并不会讲cacti的安装。
很多开源程序如mailman, nagios等等，都有web管理界面，都需要cgi支持。在Apache独大的年代，这个问题可以很好解决，因为apache本身就可以运行cgi程序。而nginx恰恰又没有cgi模块，特意去编个httpd也懒。
这时候，我们就需要配置nginx使其支持perl cgi从而保证nagios的运行。
本文的lnmp环境参考张晏老师的http://blog.s135.com/nginx_php_v6/搭建。我自己记录的lnmp编译安装。nginx采用php-fpm管理调用php处理正常的php请求，而nagios的cgi请求则通过转发给另行安装的perl cgi模块和FCGI-ProcManager来处理。
以下都是在监控服务器上操作
实现：
1.添加nagios运行用户
# groupadd nagios # useradd -s /sbin/nologin -g nagios nagios //不要加-M，不然会出现附录1：启动nagios出现warning:cannot change directory to /home/nagios的问题
2.编译安装nagios
# cd /usr/local/src/ # wget http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-3.5.0.tar.gz # tar zxvf nagios-3.5.0.tar.gz # cd nagios # ./configure --prefix=/usr/local/nagios -with-command-group=nagios # make # make install //make install出现cannot stat `nagios': No such file or directory时，请make all下 # make install-init # make install-config # make install-commandmode # vim /usr/local/nagios/etc/objects/contacts.cfg //更改email地址nagiosadmin联系人定义的为接收报警的email。默认配置文件安装在/usr/local/nagios/etc，这些样例文件可以配置Nagios使之正常运行 # /usr/local/apache2/bin/htpasswd -c /usr/local/nginx/conf/htppasswd nagiosadmin //创建一个nagiosadmin用户，用于登录nagios。这里借助apche的htpasswd。在有apache机器上执行，将生成的htppasswd拷贝到这台就可以了
3.接下来安装nagios插件
# wget http://prdownloads.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-1.4.16.tar.gz # tar zxvf nagios-plugins-1.4.16.tar.gz # cd nagios-plugins-1.4.16 # ./configure --with-nagios-user=nagios --with-nagios-group=nagios # make & make install
4.启动nagios chkconfig –add nagios添加到service 中，chkconfig nagios on设置成开机启动
# /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg 启动前，习惯性先检查下nagios.cfg配置文件是否正确 # service nagios start //启动服务 这里要关掉selinux否则访问的时候会出错。
5.安装perl cgi模块，用于处理cgi请求
# wget http://www.cpan.org/modules/by-module/FCGI/FCGI-0.74.tar.gz # tar zxvf FCGI-0.74.tar.gz # cd FCGI-0.74 # perl Makefile.PL # make && make install # cd ..
6.安装FCGI-ProcManager，用于管理FCGI
# wget http://www.cpan.org/authors/id/G/GB/GBJK/FCGI-ProcManager-0.19.tar.gz # tar zxvf FCGI-ProcManager-0.19.tar.gz # cd FCGI-ProcManager-0.19 # perl Makefile.PL # make && make install
7.下载nginx-fcgi脚本，后台守候进程，处理cgi进程
# cd /usr/local/src # wget http://dl.gaingreat.com/nginx-fcgi # mv nginx-fcgi /usr/sbin/nginx-fcgi # chmod +x /usr/sbin/nginx-fcgi # /usr/sbin/nginx-fcgi -l /var/log/nginx-fcgi.log -pid /var/run/nginx-fcgi.pid -S /var/run/nginx-fcgi.sock //启动nginx-fcgi守护进程，用于处理cgi请求 # chmod 777 /var/run/nginx-fcgi.sock //给nginx-fcgi.sock 777的权限 # perl -MCPAN -e 'install "IO::All"' //别人说要cpan安装FCGI;Getopt::Long;IO::All;Socket;但这里我就安装了IO::All，回车过去。如果IO::ALL无法cpan安装，可以到search.cpan.org下载IO::All包手动安装
8.到这里nagios基本上装完了，下来就是nginx的配置了！
# cat /usr/local/nginx/conf/vhost/nagios.conf //内容如下，可以看到php|php5语法转给127.0.0.1:9000;cgi请求则给/var/run/nginx-fcgi.sock处理
server
{
listen 80;
server_name nagios.coolnull.com;
root /usr/local/nagios/share;
index index.php;
location ~ .*\.(php|php5)?$
{
fastcgi_pass 127.0.0.1:9000;
fastcgi_index index.php;
include fastcgi.conf;
auth_basic "Nagios Login pain";
auth_basic_user_file /usr/local/nginx/conf/htppasswd;
}
location ~ .*\.cgi$ {
root /usr/local/nagios/sbin;
rewrite ^/nagios/cgi-bin/(.*)\.cgi /$1.cgi break;
fastcgi_pass unix:/var/run/nginx-fcgi.sock;
fastcgi_index index.cgi;
fastcgi_param SCRIPT_FILENAME /usr/local/nagios/sbin/$fastcgi_script_name;
fastcgi_param HTTP_ACCEPT_LANGUAGE zh-cn;
include fcgi.conf;
auth_basic "Nagios Login pain";
auth_basic_user_file /usr/local/nginx/conf/htppasswd;
}
location /nagios {
alias /usr/local/nagios/share/;
#index index.html index.htm index.php;
#auth_basic "Nagios Login pain";
#auth_basic_user_file /usr/local/nginx/conf/htppasswd;
}
error_log /tmp/error.log;
access_log /tmp/access.log access;
}
9：添加开机启动项
# vim /etc/rc.loal //内容如下 #for nagios monitor /usr/sbin/nginx-fcgi -l /var/log/nginx-fcgi.log -pid /var/run/nginx-fcgi.pid -S /var/run/nginx-fcgi.sock /bin/chmod 777 /var/run/nginx-fcgi.sock /etc/init.d/nagios start
测试：
以上步骤完成，基本就可以监控服务器自身的监控信息。
附录
附录1：启动nagios出现warning:cannot change directory to /home/nagios….或Starting nagios:This account is currently not available.
这个是因为当时安装nagios没有设好权限，给予nagios登陆权限usermod -s /bin/bash
或创建目录/home/nagios，我这里用的是mkdir /home/nagios
附录2：Can’t locate IO/All.pm
perl -MCPAN -e ‘install “IO::All”‘
Can’t locate FCGI.pm in @INC
perl -MCPAN -e ‘install FCGI’
perl -MCPAN -e ‘install FCGI::ProcManager’
cpan -i FCGI
cpan -i FCGI::ProcManager
//身份认证、数据库连接
cpan Authen::SASL Filesys::Df DBI DBD::mysql
perl-fcgi.pl(fcgi socket):
附录3.nagios搭建好后nagios右侧具体内容为乱码。左侧导航部分全英文，都正常
这是因为nagios没办法执行cgi请求，直接输出乱码出来。只要安装perl cgi模块和FCGI-ProcManager，并在nginx上添加fastcgi_pass unix:/var/run/nginx-fcgi.sock;等，让nginx能正确处理cgi请求即可！
附录4.fastcgi.conf
# cat /usr/local/nginx/conf/fastcgi.conf //内容如下 fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; fastcgi_param QUERY_STRING $query_string; fastcgi_param REQUEST_METHOD $request_method; fastcgi_param CONTENT_TYPE $content_type; fastcgi_param CONTENT_LENGTH $content_length; fastcgi_param SCRIPT_NAME $fastcgi_script_name; fastcgi_param REQUEST_URI $request_uri; fastcgi_param DOCUMENT_URI $document_uri; fastcgi_param DOCUMENT_ROOT $document_root; fastcgi_param SERVER_PROTOCOL $server_protocol; fastcgi_param HTTPS $https if_not_empty; fastcgi_param GATEWAY_INTERFACE CGI/1.1; fastcgi_param SERVER_SOFTWARE nginx/$nginx_version; fastcgi_param REMOTE_ADDR $remote_addr; fastcgi_param REMOTE_PORT $remote_port; fastcgi_param SERVER_ADDR $server_addr; fastcgi_param SERVER_PORT $server_port; fastcgi_param SERVER_NAME $server_name; # PHP only, required if PHP was built with --enable-force-cgi-redirect fastcgi_param REDIRECT_STATUS 200;
参考：
主要参考了这篇：http://liuyu.blog.51cto.com/183345/241867
nginx官网关于cgi的处理：http://wiki.nginx.org/NginxSimpleCGI，没仔细看！