新特性：
- MPM支持运行为DSO机制；以模块形式按需加载
- event MPM生产环境可用
- 异步读写机制
- 支持每模块及每目录的单独日志级别定义
- 每请求相关的专用配置
- 增强版的表达式分析式
- 毫秒级持久连接时长定义
- 基于FQDN的虚拟主机也不在需要NameVirutailHost指令
- 新指令，AllowOverrideList
- 支持用户自定义变量
- 更低的内存消耗
新模块：- mod_proxy_fcgi：支持PHP
- mod_proxy_scgi：支持python
- mode_remoteip
安装httpd2.4
依赖apr：apache protable runtime，apache可移植运行环境
依赖pcre：Per Compatible Regular Expressions，中文含义perl语言兼容正则表达式是一个用c语言编写的正则表达式函数库，pcre被广泛使用在许多开源软件之中，最著名的莫过于Apache HTTP服务器和PHP脚本语言、R脚本语言，此外，正如从其名字所能看到的，pcre也是perl语言的缺省正则库
实验环境：
[root@Centos7 data]# uname -r
3.10.0-693.el7.x86_64
[root@Centos7 data]# cat /etc/redhat-release
CentOS Linux release 7.4.1708 (Core)
[root@Centos7 data]# ls
httpd-2.4.25.tar.bz2查看本机是否有安装httpd，如有请卸载
[root@Centos7 data]# rpm -q httpd
package httpd is not installed源码编译安装httpd之前，先使用yum安装相关依赖包
[root@Centos7 data]# yum -y install gcc openssl-devel pcre-devel apr-devel apr-util-devel创建一个目录专门用于管理源码编译的程序/apps
[root@Centos7 data]# mkdir /apps解包httpd-2.4.25.tar.bz2
[root@Centos7 data]# tar xf httpd-2.4.25.tar.bz2
[root@Centos7 data]# ls
httpd-2.4.25 httpd-2.4.25.tar.bz2
[root@Centos7 data]# cd httpd-2.4.25/
[root@Centos7 httpd-2.4.25]# ls
ABOUT_APACHE BuildAll.dsp configure.in include LICENSE README test
acinclude.m4 BuildBin.dsp docs INSTALL Makefile.in README.cmake VERSIONING
Apache-apr2.dsw buildconf emacs-style InstallBin.dsp Makefile.win README.platforms
Apache.dsw CHANGES httpd.dep LAYOUT modules ROADMAP
apache_probes.d CMakeLists.txt httpd.dsp libhttpd.dep NOTICE server
ap.d config.layout httpd.mak libhttpd.dsp NWGNUmakefile srclib
build configure httpd.spec libhttpd.mak os support通过查看INSTALL文件，就基本能知道该如何去编译安装httpd
由于是简易的源码编译安装httpd，所以只需要指定一些简单的选项即可
编译安装三大步：
1、./configure
2、make
3、make install
[root@Centos7 httpd-2.4.25]# ./configure > --prefix=/apps/httpd24 \ #安装路径
> --sysconfdir=/etc/httpd \ #配置文件路径
> --enable-ssl \ #启动ssl加密功能
> --enable-so #启动共享库
configure: summary of build options:
Server Version: 2.4.25
Install prefix: /apps/httpd24
C compiler: gcc -std=gnu99
CFLAGS: -pthread
LDFLAGS:
LIBS:
CPPFLAGS: -DLINUX -D_REENTRANT -D_GNU_SOURCE
C preprocessor: gcc -E
[root@Centos7 httpd-2.4.25]# make && make install
...
Installing man pages and online manual
mkdir /apps/httpd24/man
mkdir /apps/httpd24/man/man1
mkdir /apps/httpd24/man/man8
mkdir /apps/httpd24/manual
make[1]: Leaving directory `/data/httpd-2.4.25‘设定PATH路径
[root@Centos7 httpd-2.4.25]# cd /apps/
[root@Centos7 apps]# ls
httpd24
[root@Centos7 apps]# ls httpd24/bin/
ab apxs dbmmanage envvars-std htcacheclean htdigest httpd logresolve
apachectl checkgid envvars fcgistarter htdbm htpasswd httxt2dbm rotatelogs
[root@Centos7 apps]# cd httpd24/bin/
[root@Centos7 bin]# pwd
/apps/httpd24/bin
[root@Centos7 bin]# echo "PATH=/apps/httpd24/bin:$PATH" > /etc/profile.d/httpd.sh
[root@Centos7 bin]# . /etc/profile.d/httpd.sh启动httpd24服务，访问主页
[root@Centos7 bin]# cd
[root@Centos7 ~]# apachectl start
AH00558: httpd: Could not reliably determine the server‘s fully qualified domain name, using Centos7.localdomain. Set the ‘ServerName‘ directive globally to suppress this message
[root@Centos7 ~]# ss -tn
State Recv-Q Send-Q Local Address:Port Peer Address:Port
ESTAB 0 0 10.0.17.93:22 10.0.16.89:49385
[root@Centos7 ~]# ss -tnl
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 *:111 *:*
LISTEN 0 5 192.168.122.1:53 *:*
LISTEN 0 128 *:22 *:*
LISTEN 0 128 127.0.0.1:631 *:*
LISTEN 0 100 127.0.0.1:25 *:*
LISTEN 0 128 :::111 :::*
LISTEN 0 128 :::80 :::*
LISTEN 0 128 :::22 :::*
LISTEN 0 128 ::1:631 :::*
LISTEN 0 100 ::1:25 :::*
[root@Centos7 ~]# curl http://localhost
<html><body><h1>It works!</h1></body></html>如果想开机启动，可以把apachectl start写入到/etc/rc.local 文件里