1. SQL injection
#By inserting SQL commands into Web form submissions or entering query strings for domain names or page requests, it ultimately deceives the server into executing Malicious SQL commands.
Defense: First filter, then perform parameter binding.
2. XSS
Cross Site Scripting
Principle: Embed scripts into web pages in different ways to achieve attack purposes.
Defense: Filter input.
$id = (int) $_REQUEST['id'];if( $id > 0 ){}
$name = htmlentities($_REQUEST['name'], ENT_QUOTES, "UTF-8");// 注意,如果这里不进行转化也是可以的,// 只要在输出的时候进行转化(建立在已经参数绑定的情况下)。
3. CSRF
##Cross-site request forgery Cross-site request forgery
Principle: Helen logged into Weibo and then browsed a harmful site. A fake post on Weibo was forged on the harmful site. At this time, Helen posted a Weibo without knowing it.
Defense: Embed a random token in the Weibo page, and the Weibo server verifies the token value.
4. Clickjacking
5. Upload filesClickJacking
##Principle: Approximately There are two ways. One is that the attacker uses a transparent iframe, covering it on a web page, and then induces the user to operate on the page. At this time, the user will click on the transparent iframe page without knowing it; the other is The attacker uses an image to cover the web page, blocking the original location of the web page.Defense: Use js to determine whether the frame is under the same domain name. Add header directive: X-Frame-Options.
// js if (top.location.hostname !== self.location.hostname) { alert("您正在访问不安全的页面,即将跳转到安全页面!"); top.location.href = self.location.href;}// Apache 配置:Header always append X-Frame-Options SAMEORIGIN// nginx 配置:add_header X-Frame-Options SAMEORIGIN;
Principle: Various types of illegal software may be uploaded.6. zip *Defense: detection type, detection size.
Principle: Some zip files look very small but are very large after decompression7. Session hijackingDefense: Do not do this: decompress, process, and then compress compressed files uploaded by users. Because when you decompress, your server is likely to be crowded.
Principle: When the client and server communicate, the hacker captures the packet and obtains the sessionid , and eventually the hacker communicates with the server.8. Password storageDefense:
Set HttpOnly and reset sessionid from time to time.
$hashedPassword = password_hash('password', PASSWORD_DEFAULT);password_verify('the wrong password', $hashedPassword); // falsepassword_verify('my super cool password', $hashedPassword); // true
9. Brute force cracking/**防御:1. 限制次数2. 验证码3. 防火墙分析 类似 fail2ban*/
server Security1. Modify port 22
vi /etc/ssh/sshd_configfirewall-cmd --list-allfirewall-cmd --add-port=8888/tcp --permanentfirewall-cmd --reload# 如果是阿里云服务器,不要忘记修改阿里云安全组
2. Modify mysql root name# 修改 mysql 数据库中的 user 表,然后 flush privileges
3. Prohibit root remote loginvi /etc/ssh/sshd_configPermitRootLogin
web security
1. sql injection
By inserting SQL commands into Web form submissions or entering domain names or query strings for page requests, the server is ultimately tricked into executing malicious SQL commands.2. XSSDefense: First filter, then perform parameter binding.
Cross Site Scripting3. CSRFPrinciple: Embed scripts into web pages in different ways to achieve attack purposes.
Defense: Filter input.
$id = (int) $_REQUEST['id'];if( $id > 0 ){}$name = htmlentities($_REQUEST['name'], ENT_QUOTES, "UTF-8");// 注意,如果这里不进行转化也是可以的,// 只要在输出的时候进行转化(建立在已经参数绑定的情况下)。
##Cross-site request forgery Cross-site request forgery
Principle: Helen logged into Weibo and then browsed a harmful site. A fake post on Weibo was forged on the harmful site. At this time, Helen posted a Weibo without knowing it.
Defense: Embed a random token in the Weibo page, and the Weibo server verifies the token value.
4. Clickjacking
ClickJacking
原理:大概有两种方式,一是攻击者使用一个透明的 iframe ,覆盖在一个网页上,然后诱使用户在该页面上进行操作,此时用户将在不知情的情况下点击透明的 iframe 页面;二是攻击者使用一张图片覆盖在网页,遮挡网页原有位置。
防御:使用 js 判断框架是否在同一个域名下。添加头部指令: X-Frame-Options。
// js if (top.location.hostname !== self.location.hostname) { alert("您正在访问不安全的页面,即将跳转到安全页面!"); top.location.href = self.location.href;}// Apache 配置:Header always append X-Frame-Options SAMEORIGIN// nginx 配置:add_header X-Frame-Options SAMEORIGIN;
5. 上传文件
原理:可能会被上传各种类型的非法软件。
防御:检测类型,检测大小。
6. zip *
原理:有些 zip 文件看起来很小,解压后非常大
防御:不要做这样的操作:对用户上传的压缩文件解压,处理,再压缩。因为你解压的时候,很可能你的服务器就被挤爆了。
7. session 劫持
原理:客户端和服务端通信时候,黑客抓包,获取 sessionid ,最终黑客与服务器通信。
防御:
设置 HttpOnly,时常重设 sessionid。
8. 密码存储
$hashedPassword = password_hash('password', PASSWORD_DEFAULT);password_verify('the wrong password', $hashedPassword); // falsepassword_verify('my super cool password', $hashedPassword); // true
9. 暴力破解
/**防御:1. 限制次数2. 验证码3. 防火墙分析 类似 fail2ban*/
服务器安全
1. 修改 22 端口
vi /etc/ssh/sshd_configfirewall-cmd --list-allfirewall-cmd --add-port=8888/tcp --permanentfirewall-cmd --reload# 如果是阿里云服务器,不要忘记修改阿里云安全组
2. 修改 mysql root 名称
# 修改 mysql 数据库中的 user 表,然后 flush privileges
3. 禁止 root 远程登陆
vi /etc/ssh/sshd_configPermitRootLogin
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php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

php判断有没有小数点的方法:1、使用“strpos(数字字符串,'.')”语法,如果返回小数点在字符串中第一次出现的位置,则有小数点;2、使用“strrpos(数字字符串,'.')”语句,如果返回小数点在字符串中最后一次出现的位置,则有。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

在php中,可以使用substr()函数来读取字符串后几个字符,只需要将该函数的第二个参数设置为负值,第三个参数省略即可;语法为“substr(字符串,-n)”,表示读取从字符串结尾处向前数第n个字符开始,直到字符串结尾的全部字符。


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