摘要： 容器服务中，除了slb之外，自定义路由服务（基于HAProxy）也可以作为DDOS攻击的一道防线，本文阐述了几种方法来应对普通规模的DDOS攻击
1. TCP洪水攻击（SYN Flood）
ECS系统参数调整，应对TCP洪水攻击，打开文件/etc/sysctl.conf，配置如下参数
# Protection SYN flood
net.ipv4.tcp_syncookies = 1
net.ipv4.conf.all.rp_filter = 1
net.ipv4.tcp_max_syn_backlog = 1024
执行如下命令，使配置文件生效
sysctl -p
2. 慢速连接攻击
一个 Http 请求通常包括头部、url、methods 等，服务器需要接收整个 Http 请求后会做出响应。恶意用户发送缓慢的 Http 请求，比如一个字节一个字节的发送头部，服务器将一直处于 wating 状态，从而耗费服务器的资源。Haproxy 通过配置 timeout http-request 参数，当一个用户的请求时间超过设定值时，Haproxy 断开与该用户的连接。示例compose模板如下：
lb:
image: registry.aliyuncs.com/acs/proxy:0.5
ports:
- '80:80'
restart: always
labels:
# addon 使得proxy镜像有订阅注册中心的能力，动态加载服务的路由
aliyun.custom_addon: "proxy"
# 每台vm 部署一个该镜像的容器
aliyun.global: "true"
# 前端绑定SLB
aliyun.lb.port_80: tcp://proxy_test:80
environment:
# 支持加载路由的后端容器的范围，"*"表示整个集群，默认为应用内的服务
ADDITIONAL_SERVICES: "*"
EXTRA_DEFAULT_SETTINGS: 'timeout http-request 5s'
appone:
ports:
- 80/tcp
- 443/tcp
image: 'registry.cn-hangzhou.aliyuncs.com/linhuatest/hello-world:latest'
labels:
# 此处支持http/https/ws/wss 协议
aliyun.proxy.VIRTUAL_HOST: "http://appone.example.com"
restart: always
生成的HAProxy配置文件为：
global
log 127.0.0.1 local0
log 127.0.0.1 local1 notice
log-send-hostname
maxconn 4096
pidfile /var/run/haproxy.pid
user haproxy
group haproxy
daemon
stats socket /var/run/haproxy.stats level admin
ssl-default-bind-options no-sslv3
ssl-default-bind-ciphers ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES128-SHA:DHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:AES128-GCM-SHA256:AES128-SHA256:AES128-SHA:AES256-GCM-SHA384:AES256-SHA256:AES256-SHA:DHE-DSS-AES128-SHA:DES-CBC3-SHA
defaults
balance roundrobin
log global
mode http
option redispatch
option httplog
option dontlognull
option forwardfor
timeout connect 5000
timeout client 50000
timeout server 50000
timeout http-request 5s # 该处指令应对慢速连接攻击
listen stats
bind :1936
mode http
stats enable
timeout connect 10s
timeout client 1m
timeout server 1m
stats hide-version
stats realm Haproxy\ Statistics
stats uri /
stats auth stats:stats
frontend port_80
bind :80
reqadd X-Forwarded-Proto:\ http
maxconn 4096
acl is_websocket hdr(Upgrade) -i WebSocket
acl host_rule_1 hdr(host) -i appone.example.com
acl host_rule_1_port hdr(host) -i appone.example.com:80
use_backend SERVICE_test-routing_appone if host_rule_1 or host_rule_1_port
backend SERVICE_test-routing_appone
server test-routing_appone_1 172.19.0.8:443 check inter 2000 rise 2 fall 3
server test-routing_appone_1 172.19.0.8:80 check inter 2000 rise 2 fall 3
通过 telnet 登录验证结果
$ telnet 120.76.43.112 80
Trying 120.76.43.112...
Connected to 120.76.43.112.
Escape character is '^]'.
HTTP/1.0 408 Request Time-out
Cache-Control: no-cache
Connection: close
Content-Type: text/html
<html><body><h1>408 Request Time-out</h1>
Your browser didn't send a complete request in time.
</body></html>
Connection closed by foreign host.
3. 限制每个用户的并发连接数量
以网站为例，普通用户访问网站，或者从网站下载东西时，浏览器一般会建立 5-7 个 TCP 链接。当一个恶意打开了大量 TCP 链接时，耗费服务器大量资源，影响其它用户的访问，因此我们需要根据实际情况，限制同一个用户的链接数。示例compose模板如下：
lb:
image: registry.aliyuncs.com/acs/proxy:0.5
ports:
- '80:80'
restart: always
labels:
# addon 使得proxy镜像有订阅注册中心的能力，动态加载服务的路由
aliyun.custom_addon: "proxy"
# 每台vm 部署一个该镜像的容器
aliyun.global: "true"
# 前端绑定SLB
aliyun.lb.port_80: tcp://proxy_test:80
environment:
# 支持加载路由的后端容器的范围，"*"表示整个集群，默认为应用内的服务
ADDITIONAL_SERVICES: "*"
EXTRA_DEFAULT_SETTINGS: 'timeout http-request 5s'
EXTRA_FRONTEND_SETTINGS_80: 'stick-table type ip size 100k expire 30s store conn_cur,# Shut the new connection as long as the client has already 10 opened,tcp-request connection reject if { src_conn_cur ge 10 },tcp-request connection track-sc1 src'
appone:
ports:
- 80/tcp
- 443/tcp
image: 'registry.cn-hangzhou.aliyuncs.com/linhuatest/hello-world:latest'
labels:
# 此处支持http/https/ws/wss 协议
aliyun.proxy.VIRTUAL_HOST: "http://appone.example.com"
restart: always
生成的HAProxy配置文件为：
global
log 127.0.0.1 local0
log 127.0.0.1 local1 notice
log-send-hostname
maxconn 4096
pidfile /var/run/haproxy.pid
user haproxy
group haproxy
daemon
stats socket /var/run/haproxy.stats level admin
ssl-default-bind-options no-sslv3
ssl-default-bind-ciphers ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES128-SHA:DHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:AES128-GCM-SHA256:AES128-SHA256:AES128-SHA:AES256-GCM-SHA384:AES256-SHA256:AES256-SHA:DHE-DSS-AES128-SHA:DES-CBC3-SHA
defaults
balance roundrobin
log global
mode http
option redispatch
option httplog
option dontlognull
option forwardfor
timeout connect 5000
timeout client 50000
timeout server 50000
timeout http-request 5s
listen stats
bind :1936
mode http
stats enable
timeout connect 10s
timeout client 1m
timeout server 1m
stats hide-version
stats realm Haproxy\ Statistics
stats uri /
stats auth stats:stats
frontend port_80
bind :80
reqadd X-Forwarded-Proto:\ http
maxconn 4096
stick-table type ip size 100k expire 30s store conn_cur
# Shut the new connection as long as the client has already 10 opened
tcp-request connection reject if { src_conn_cur ge 10 }
tcp-request connection track-sc1 src
acl is_websocket hdr(Upgrade) -i WebSocket
acl host_rule_1 hdr(host) -i appone.example.com
acl host_rule_1_port hdr(host) -i appone.example.com:80
use_backend SERVICE_test-routing_appone if host_rule_1 or host_rule_1_port
backend SERVICE_test-routing_appone
server test-routing_appone_1 172.19.0.8:443 check inter 2000 rise 2 fall 3
server test-routing_appone_1 172.19.0.8:80 check inter 2000 rise 2 fall 3
利用 apache 测试工具做验证，和服务器一直保持建立 10 个链接。
$ ab -H"host:appone.example.com" -n 5000000 -c 10 http://127.0.0.1:80/
用 telnet 打开第 11 个链接，服务器拒绝该链接。
$ telnet 127.0.0.1 80
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
Connection closed by foreign host.
4. 限制每个用户建立连接速度
仅仅限制单个用户的并发链接数并意味着万事大吉，如果用户在短时间内向服务器不断的发送建立和关闭链接请求，也会耗费服务器资源，影响服务器端的性能，因此需要控制单个用户的访问速率。
通常情况下，考虑到用户通过浏览器一般会建立 5-7 条 TCP 链接，我们可以认为普通用户在 3 秒内不应该建立超过 10 条链接。示例compose模板如下：
lb:
image: registry.aliyuncs.com/acs/proxy:0.5
ports:
- '80:80'
restart: always
labels:
# addon 使得proxy镜像有订阅注册中心的能力，动态加载服务的路由
aliyun.custom_addon: "proxy"
# 每台vm 部署一个该镜像的容器
aliyun.global: "true"
# 前端绑定SLB
aliyun.lb.port_80: tcp://proxy_test:80
environment:
# 支持加载路由的后端容器的范围，"*"表示整个集群，默认为应用内的服务
ADDITIONAL_SERVICES: "*"
EXTRA_DEFAULT_SETTINGS: 'timeout http-request 5s'
EXTRA_FRONTEND_SETTINGS_80: '# Table definition,stick-table type ip size 100k expire 30s store conn_rate(3s),# Shut the new connection as long as the client has already 10 opened,tcp-request connection reject if { src_conn_rate ge 10 },tcp-request connection track-sc1 src'
appone:
ports:
- 80/tcp
- 443/tcp
image: 'registry.cn-hangzhou.aliyuncs.com/linhuatest/hello-world:latest'
labels:
# 此处支持http/https/ws/wss 协议
aliyun.proxy.VIRTUAL_HOST: "http://appone.example.com"
restart: always
生成的配置为：
global
log 127.0.0.1 local0
log 127.0.0.1 local1 notice
log-send-hostname
maxconn 4096
pidfile /var/run/haproxy.pid
user haproxy
group haproxy
daemon
stats socket /var/run/haproxy.stats level admin
ssl-default-bind-options no-sslv3
ssl-default-bind-ciphers ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES128-SHA:DHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:AES128-GCM-SHA256:AES128-SHA256:AES128-SHA:AES256-GCM-SHA384:AES256-SHA256:AES256-SHA:DHE-DSS-AES128-SHA:DES-CBC3-SHA
defaults
balance roundrobin
log global
mode http
option redispatch
option httplog
option dontlognull
option forwardfor
timeout connect 5000
timeout client 50000
timeout server 50000
timeout http-request 5s
listen stats
bind :1936
mode http
stats enable
timeout connect 10s
timeout client 1m
timeout server 1m
stats hide-version
stats realm Haproxy\ Statistics
stats uri /
stats auth stats:stats
frontend port_80
bind :80
reqadd X-Forwarded-Proto:\ http
maxconn 4096
# Table definition
stick-table type ip size 100k expire 30s store conn_rate(3s)
# Shut the new connection as long as the client has already 10 opened
tcp-request connection reject if { src_conn_rate ge 10 }
tcp-request connection track-sc1 src
acl is_websocket hdr(Upgrade) -i WebSocket
acl host_rule_1 hdr(host) -i appone.example.com
acl host_rule_1_port hdr(host) -i appone.example.com:80
use_backend SERVICE_test-routing_appone if host_rule_1 or host_rule_1_port
backend SERVICE_test-routing_appone
server test-routing_appone_1 172.19.0.8:443 check inter 2000 rise 2 fall 3
server test-routing_appone_1 172.19.0.8:80 check inter 2000 rise 2 fall 3
测试，采用 ab 打开 10 个链接。
$ ab -n 10 -c 1 -r http://127.0.0.1:8080/
再用 telnet 打开第 11 个链接，服务器拒绝该请求。
$ telnet 127.0.0.1 80
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
Connection closed by foreign host.