【Web开发】使用Apache搭建Http下载服务器

前言

前段时间因为某些原因，几大主流网盘都无法使用，正好手头上有台闲置的云服务器，于是就想来搭建一个文件下载服务，用户只需通过一个链接就能下载软件。

Apache快速上手

经过调研，发现Ubuntu采用Apache2这个软件就可以快速满足我的需求。

安装Apache2

apt-get install apache2

安装好之后，启动Apache2服务：

/etc/init.d/apache2 start

查看启动状态：

/etc/init.d/apache2 status

然后，访问服务器的公网ip或域名，就可以看到如下界面，此时说明Apache正常工作：

最后在​​/var/www/html​​​路径下，删除​​index.html​​​，上传自己想要被下载的文件，再次访问，就可以进行下载了。
(注：如果是云服务器，还需要在安全组开放80和443端口号)
同时，也可以通过​​​域名/文件名​​的方式直接给别人一个链接，进行下载。

如果有一台单独的服务器用于临时文件的分享，这样很快就搞定了。
下面来继续进行深入研究，考虑更现实的场景。

修改端口号

Apache2默认采用的是80端口号，因此直接通过公网ip或域名就能访问。现实中，很多服务器本身就部署了许多其它服务，80端口号往往被占用，因此就需要将Apache2改成其它访问端口。

修改端口，首先需要修改​​/etc/apache2/ports.conf​​​这个文件：
这里吧80改成其它不冲突的端口号，我这里以1024为例

#Listen 80
Listen 1024
 
 
<IfModule ssl_module>
        Listen 443
</IfModule>
 
 
<IfModule mod_gnutls.c>
        Listen 443
</IfModule>

然后修改​​/etc/apache2/sites-available/000-default.conf​​

#<VirtualHost *:80>
<VirtualHost *:1024>
        # The ServerName directive sets the request scheme, hostname and port that
        # the server uses to identify itself. This is used when creating

注：这个文件中还有一个​​DocumentRoot​​，修改该参数可以调整文件系统的根路径。

修改完成之后，重启apache2：

/etc/init.d/apache2 restart

此时，就可以通过访问​​域名:1024​​​的形式访问到同样内容，例如我的服务器访问url为​​http://xdxsb.top:1024​​

设置访问限制

个人服务器很容易遭到别人的攻击，如果有人开好多线程来反复请求下载，这就将导致流量带宽消耗巨大，甚至会让服务器宕机。因此，长期提供下载服务的服务器必须设置访问限制。

配置文件参数详解

访问限制主要涉及到​​/etc/apache2/apache2.conf​​​这个配置文件，首先来对该文件进行解读。
这个文件内容如下：

# This is the main Apache server configuration file.  It contains the
# configuration directives that give the server its instructions.
# See http://httpd.apache.org/docs/2.4/ for detailed information about
# the directives and /usr/share/doc/apache2/README.Debian about Debian specific
# hints.
#
#
# Summary of how the Apache 2 configuration works in Debian:
# The Apache 2 web server configuration in Debian is quite different to
# upstream's suggested way to configure the web server. This is because Debian's
# default Apache2 installation attempts to make adding and removing modules,
# virtual hosts, and extra configuration directives as flexible as possible, in
# order to make automating the changes and administering the server as easy as
# possible.

# It is split into several files forming the configuration hierarchy outlined
# below, all located in the /etc/apache2/ directory:
#
# /etc/apache2/
# |-- apache2.conf
# | `--  ports.conf
# |-- mods-enabled
# | |-- *.load
# | `-- *.conf
# |-- conf-enabled
# | `-- *.conf
#   `-- sites-enabled
#   `-- *.conf
#
#
# * apache2.conf is the main configuration file (this file). It puts the pieces
#   together by including all remaining configuration files when starting up the
#   web server.
#
# * ports.conf is always included from the main configuration file. It is
#   supposed to determine listening ports for incoming connections which can be
#   customized anytime.
#
# * Configuration files in the mods-enabled/, conf-enabled/ and sites-enabled/
#   directories contain particular configuration snippets which manage modules,
#   global configuration fragments, or virtual host configurations,
#   respectively.
#
#   They are activated by symlinking available configuration files from their
#   respective *-available/ counterparts. These should be managed by using our
#   helpers a2enmod/a2dismod, a2ensite/a2dissite and a2enconf/a2disconf. See
#   their respective man pages for detailed information.
#
# * The binary is called apache2. Due to the use of environment variables, in
#   the default configuration, apache2 needs to be started/stopped with
#   /etc/init.d/apache2 or apache2ctl. Calling /usr/bin/apache2 directly will not
#   work with the default configuration.


# Global configuration
#

#
# ServerRoot: The top of the directory tree under which the server's
# configuration, error, and log files are kept.
#
# NOTE!  If you intend to place this on an NFS (or otherwise network)
# mounted filesystem then please read the Mutex documentation (available
# at <URL:http://httpd.apache.org/docs/2.4/mod/core.html#mutex>);
# you will save yourself a lot of trouble.
#
# Do NOT add a slash at the end of the directory path.
#
#ServerRoot "/etc/apache2"

#
# The accept serialization lock file MUST BE STORED ON A LOCAL DISK.
#
#Mutex file:${APACHE_LOCK_DIR} default

#
# The directory where shm and other runtime files will be stored.
#

DefaultRuntimeDir ${APACHE_RUN_DIR}

#
# PidFile: The file in which the server should record its process
# identification number when it starts.
# This needs to be set in /etc/apache2/envvars
#
PidFile ${APACHE_PID_FILE}

#
# Timeout: The number of seconds before receives and sends time out.
#
Timeout 300

#
# KeepAlive: Whether or not to allow persistent connections (more than
# one request per connection). Set to "Off" to deactivate.
#
KeepAlive On

#
# MaxKeepAliveRequests: The maximum number of requests to allow
# during a persistent connection. Set to 0 to allow an unlimited amount.
# We recommend you leave this number high, for maximum performance.
#
MaxKeepAliveRequests 100

#
# KeepAliveTimeout: Number of seconds to wait for the next request from the
# same client on the same connection.
#
KeepAliveTimeout 5


# These need to be set in /etc/apache2/envvars
User ${APACHE_RUN_USER}
Group ${APACHE_RUN_GROUP}

#
# HostnameLookups: Log the names of clients or just their IP addresses
# e.g., www.apache.org (on) or 204.62.129.132 (off).
# The default is off because it'd be overall better for the net if people
# had to knowingly turn this feature on, since enabling it means that
# each client request will result in AT LEAST one lookup request to the
# nameserver.
#
HostnameLookups Off

# ErrorLog: The location of the error log file.
# If you do not specify an ErrorLog directive within a <VirtualHost>
# container, error messages relating to that virtual host will be
# logged here.  If you *do* define an error logfile for a <VirtualHost>
# container, that host's errors will be logged there and not here.
#
ErrorLog ${APACHE_LOG_DIR}/error.log

#
# LogLevel: Control the severity of messages logged to the error_log.
# Available values: trace8, ..., trace1, debug, info, notice, warn,
# error, crit, alert, emerg.
# It is also possible to configure the log level for particular modules, e.g.
# "LogLevel info ssl:warn"
#
LogLevel warn

# Include module configuration:
IncludeOptional mods-enabled/*.load
IncludeOptional mods-enabled/*.conf

# Include list of ports to listen on
Include ports.conf


# Sets the default security model of the Apache2 HTTPD server. It does
# not allow access to the root filesystem outside of /usr/share and /var/www.
# The former is used by web applications packaged in Debian,
# the latter may be used for local directories served by the web server. If
# your system is serving content from a sub-directory in /srv you must allow
# access here, or in any related virtual host.
<Directory />
  Options FollowSymLinks
  AllowOverride None
  Require all denied
</Directory>

<Directory /usr/share>
  AllowOverride None
  Require all granted
</Directory>

<Directory /var/www/>
  Options Indexes FollowSymLinks
  AllowOverride None
  Require all granted
</Directory>

#<Directory /srv/>
# Options Indexes FollowSymLinks
# AllowOverride None
# Require all granted
#</Directory>




# AccessFileName: The name of the file to look for in each directory
# for additional configuration directives.  See also the AllowOverride
# directive.
#
AccessFileName .htaccess

#
# The following lines prevent .htaccess and .htpasswd files from being
# viewed by Web clients.
#
<FilesMatch "^\.ht">
  Require all denied
</FilesMatch>


#
# The following directives define some format nicknames for use with
# a CustomLog directive.
#
# These deviate from the Common Log Format definitions in that they use %O
# (the actual bytes sent including headers) instead of %b (the size of the
# requested file), because the latter makes it impossible to detect partial
# requests.
#
# Note that the use of %{X-Forwarded-For}i instead of %h is not recommended.
# Use mod_remoteip instead.
#
LogFormat "%v:%p %h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" vhost_combined
LogFormat "%h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" combined
LogFormat "%h %l %u %t \"%r\" %>s %O" common
LogFormat "%{Referer}i -> %U" referer
LogFormat "%{User-agent}i" agent

# Include of directories ignores editors' and dpkg's backup files,
# see README.Debian for details.

# Include generic snippets of statements
IncludeOptional conf-enabled/*.conf

# Include the virtual host configurations:
IncludeOptional sites-enabled/*.conf

# vim: syntax=apache ts=4 sw=4 sts=4 sr noet

参数解释：

• PidFile:记录服务器启动进程号的文件
• Timeout:接收和发送前超时秒数
• KeepAlive:是否允许稳固的连接(每个连接有多个请求)，设为"Off"则停用
• MaxKeepAliveRequests:在稳固连接期间允许的最大请求数，设为0表示无限制接入
• KeepAliveTimeout:在同一个连接上从同一台客户上接收请求的秒数
• User/Group:运行的用户和组
• HostnameLookups：指定记录用户端的名字还是IP地址
  例如，本指令为on时记录主机名，如www.apache.org；为off时记录IP地址，204.62.129.132。默认值为off，这要比设为on好得多，因为如果设为on则每个用户端请求都将会至少造成对 nameserver 进行一次查询。
• ErrorLog:错误日志文件定位
• LogLevel:控制记录在错误日志文件中的日志信息
  可选值：debug，info，notice，warn，error，crit，alert，emerg
• Directory：在标签对里面可以设置各文件夹属性

• Options：控制在特定目录中将使用哪些服务器特性

• All：除MultiViews之外的所有特性，这是默认设置
• ExecCG：允许使用mod_cgi执行CGI脚本
• FollowSymLinks：服务器允许在此目录中使用符号连接，如果此配置位于配置段中，则会被忽略
• Includes：允许使用mod_include提供的服务器端包含
• IncludesNOEXEC：允许服务器端包含，但禁用"#exec cmd"和"#exec cgi"，但仍可以从ScriptAlias目录使用"#include virtual"虚拟CGI脚本
• Indexes：如果一个映射到目录的URL被请求，而此目录中又没有DirectoryIndex(例如：index.html)，那么服务器会返回由mod_autoindex生成的一个格式化后的目录列表
• MultiViews：允许使用mod_negotiation提供内容协商的"多重视图"(MultiViews)
• SymLinksIfOwnerMatch：服务器仅在符号连接与其目的目录或文件的拥有者具有相同的uid时才使用它。 如果此配置出现在配置段中，则将被忽略

• AllowOverride：确定允许存在于.htaccess文件中的指令类型
  语法：AllowOverride All|None|directive-type [directive-type]
  如果此指令被设置为None ，那么.htaccess文件将被完全忽略。
  directive-type可以是下列各组指令之一：

• AuthConfig : 允许使用与认证授权相关的指令
• FileInfo : 允许使用控制文档类型的指令、控制文档元数据的指令、mod_rewrite中的指令、mod_actions中的Action指令
• Indexes : 允许使用控制目录索引的指令
• Limit : 允许使用控制主机访问的指令

• Order：控制默认的访问状态与Allow和Deny指令生效的顺序

• Deny,Allow : Deny指令在Allow指令之前被评估。默认允许所有访问。任何不匹配Deny指令或者匹配Allow指令的客户都被允许访问
• Allow,Deny : Allow指令在Deny指令之前被评估。默认拒绝所有访问。任何不匹配Allow指令或者匹配Deny指令的客户都将被禁止访问
• Mutual-failure : 只有出现在Allow列表并且不出现在Deny列表中的主机才被允许访问。这种顺序与"Order Allow,Deny"具有同样效果

• Allow：控制哪些主机可以访问服务器的该区域。可以根据主机名、IP地址、 IP地址范围或其他环境变量中捕获的客户端请求特性进行控制。
  语法：Allow from all|host|env=env-variable [host|env=env-variable]
• Deny：控制哪些主机被禁止访问服务器的该区域。可以根据主机名、IP地址、 IP地址范围或其他环境变量中捕获的客户端请求特性进行控制。
  语法：Deny from all|host|env=env-variable [host|env=env-variable]
• Require：访问限制
  - all granted：表示允许所有主机访问
  - all denied：表示拒绝所有主机访问
  - local：表示仅允许本地主机访问
  - [not] host <主机名或域名列表>：表示允许或拒绝指定主机或域名访问
  - [not] ip <IP地址或网段列表>：表示允许或拒绝指定的IP地址或网段访问

• AccessFileName：设置分布式配置文件的名字，默认为.htaccess
  如果为某个目录启用了分布式配置文件功能，那么在向客户端返回其中的文档时，服务器将在这个文档所在的各级目录中查找此配置文件
• <FilesMatch"^.ht">：拒绝对.ht开头文件的访问,以保护.htaccess文件
• LogFormat：定义访问日志的格式

限制连接量

通过上面对配置文件参数的研究，注意到​​MaxKeepAliveRequests​​​这个参数限制了对于单个连接最大的访问量为100，因此无需担心单线程脚本反复频繁请求的问题。
那么对于高并发的请求，Apache是否有默认设置的策略呢？也是有的，从2.0开始，apache引入了MPM（Multi-Processing Module，多进程处理模块），MPM有prefork, worker和event这三种模式[4]，可以通过下面的命令查看当前apache所采用的模式：

apachectl -V | grep -i mpm

默认采用的应该是event模式。

这个模式的配置文件位于​​/etc/apache2/mods-availablempm_event.conf​​ 默认参数：

<IfModule mpm_event_module>
        StartServers             2
        MinSpareThreads          25
        MaxSpareThreads          75
        ThreadLimit              64
        ThreadsPerChild          25
        MaxRequestWorkers        150
        MaxConnectionsPerChild   0
</IfModule>

参数解释：

• StartServers：启动时进程数
• MinSpareThreads：最小空闲线程数
• MaxSpareThreads：最大空闲线程数
• ThreadLimit：每个进程可以启动的线程数量上限值
• ThreadsPerChild：每个进程可以启动的线程数量
• MaxRequestWorkers：线程数量最大值
• MaxConnectionsPerChild：最大连接数限制

我这里没去调整，先用JMeter来进行一个多线程并发测试：
JMeter下载地址：​​​https://jmeter.apache.org/download_jmeter.cgi​​

解压之后，运行​​apache-jmeter-5.5/bin/jmeter.bat​​，即可启动。

创建一个线程组，我这设置了1000个线程数，时间设为0.01秒

再设置HTTP请求，填写请求域名，端口号，文件路径

测试结果显示，请求失败率为16%，因此我这小破服务器，基本上1000个并发请求都难以满足。

封禁ip

如果面对恶意攻击，那最快解决问题的办法无疑是封禁它的ip，这里尝试一下封禁本机ip，看看是否有效。

首先查询本机ip，直接在百度搜索​​ip​​​，即可查询到公网ip，注意这里一定要是公网ip，通过​​ipconfig​​查询出的是内网ip。

修改配置文件：

vim /etc/apache2/apache2.conf

修改​​/var/www/​​文件内容：

<Directory /var/www/>
        Options Indexes FollowSymLinks
        AllowOverride None
        <RequireAll>
                Require all granted
                Require not ip 111.11.81.152
        </RequireAll>
</Directory>

重启服务：

/etc/init.d/apache2 restart

再次访问，发现权限受限，说明设置成功。

拓展：如果只允许某个固定ip访问，那么可以这样修改：

<Directory /var/www/>
        Options Indexes FollowSymLinks
        AllowOverride None
        # Require all granted
        Require ip 111.11.82.8
</Directory>

设置账号密码访问

对于某些私密文件，可以进一步配置账号密码进行身份验证。

首先创建一个文件夹用来保存用户信息：

mkdir -p /usr/local/conf

然后创建用户：

htpasswd -c /usr/local/conf/.usr zstar

​​zstar​​是我创建的用户名

输入密码后，Apache会以密文方式存储密码，可以通过下面的方式查看用户名和密码密文：

cat /usr/local/conf/.usr

再次修改配置文件：

vim /etc/apache2/apache2.conf

修改内容：

<Directory /var/www/>
        Options Indexes FollowSymLinks
        AllowOverride All
        AuthName "apache"
        AuthType Basic
        AuthUserFile "/usr/local/conf/.usr"
        Require user zstar
</Directory>

重启服务：

/etc/init.d/apache2 restart

再次访问，成功弹出登录验证，说明配置成功。