TL;DR
┏╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍┓
┌───────────────┐ ┃ Network ┃
│ table: filter │ ┗━━━━━━━┳━━━━━━━┛
│ chain: INPUT │◀────┐ │
└───────┬───────┘ │ ▼
│ │ ┌───────────────────┐
┌ ▼ ┐ │ │ table: nat │
│local process│ │ │ chain: PREROUTING │
└ ┘ │ └─────────┬─────────┘
│ │ │
▼ │ ▼ ┌─────────────────┐
┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅ │ ┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅ │table: nat │
Routing decision └───── outing decision ─────▶│chain: PREROUTING│
┅┅┅┅┅┅┅┅┅┳┅┅┅┅┅┅┅┅┅ ┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅ └────────┬────────┘
│ │
▼ │
┌───────────────┐ │
│ table: nat │ ┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅ │
│ chain: OUTPUT │ ┌─────▶ outing decision ◀──────────────┘
└───────┬───────┘ │ ┅┅┅┅┅┅┅┅┳┅┅┅┅┅┅┅┅
│ │ │
▼ │ ▼
┌───────────────┐ │ ┌────────────────────┐
│ table: filter │ │ │ chain: POSTROUTING │
│ chain: OUTPUT ├────┘ └──────────┬─────────┘
└───────────────┘ │
▼
┏╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍┓
┃ Network ┃
┗━━━━━━━━━━━━━━━┛
iptables -F # 清空所有的防火墙规则
iptables -X # 删除用户自定义的空链
iptables -Z # 清空计数
# 设置默认的规则
iptables -P INPUT DROP # 配置默认的不让进
iptables -P FORWARD DROP # 默认的不允许转发
iptables -P OUTPUT ACCEPT # 默认的可以出去
# 清除已有规则
iptables -F INPUT # 清空指定链 INPUT 上面的所有规则
iptables -X INPUT # 删除指定的链，这个链必须没有被其它任何规则引用，而且这条上必须没有任何规则。如果没有指定链名，则会删除该表中所有非内置的链。
iptables -Z INPUT # 把指定链，或者表中的所有链上的所有计数器清零。
# 配置允许ssh端口连接
iptables -A INPUT -s 192.168.1.0/24 -p tcp --dport 22 -j ACCEPT
# 22为你的ssh端口， -s 192.168.1.0/24表示允许这个网段的机器来连接，其它网段的ip地址是登陆不了你的机器的。 -j ACCEPT表示接受这样的请求
## 允许本地回环地址可以正常使用
iptables -A INPUT -i lo -j ACCEPT
#本地圆环地址就是那个127.0.0.1，是本机上使用的,它进与出都设置为允许
iptables -A OUTPUT -o lo -j ACCEPT
# 配置白名单
iptables -A INPUT -p all -s 192.168.1.0/24 -j ACCEPT # 允许机房内网机器可以访问
iptables -A INPUT -p all -s 192.168.140.0/24 -j ACCEPT # 允许机房内网机器可以访问
iptables -A INPUT -p tcp -s 183.121.3.7 --dport 3380 -j ACCEPT # 允许183.121.3.7访问本机的3380端口
# 开启相应的服务端口
iptables -A INPUT -p tcp --dport 80 -j ACCEPT # 开启80端口，因为web对外都是这个端口
iptables -A INPUT -p icmp --icmp-type 8 -j ACCEPT # 允许被ping
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT # 已经建立的连接得让它进来
# 保存规则到配置文件中
cp /etc/sysconfig/iptables /etc/sysconfig/iptables.bak # 任何改动之前先备份，请保持这一优秀的习惯
iptables-save > /etc/sysconfig/iptables
cat /etc/sysconfig/iptables
# 列出已设置的规则
## > iptables -L [-t 表名] [链名]
### - 四个表名 `raw`，`nat`，`filter`，`mangle`
### - 五个规则链名 `INPUT`、`OUTPUT`、`FORWARD`、`PREROUTING`、`POSTROUTING`
### - filter表包含`INPUT`、`OUTPUT`、`FORWARD`三个规则链
iptables -L -t nat # 列出 nat 上面的所有规则 ^ -t 参数指定，必须是 raw， nat，filter，mangle 中的一个
iptables -L -t nat --line-numbers # 规则带编号
iptables -L INPUT
iptables -L -nv # 查看，这个列表看起来更详细
# 将所有iptables以序号标记显示，执行：
iptables -L -n --line-numbers
# 比如要删除INPUT里序号为8的规则，执行：
iptables -D INPUT 8
# 删除已添加的规则
iptables -A INPUT -s 192.168.1.5 -j DROP
# 开放指定的端口
iptables -A INPUT -s 127.0.0.1 -d 127.0.0.1 -j ACCEPT #允许本地回环接口(即运行本机访问本机)
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT #允许已建立的或相关连的通行
iptables -A OUTPUT -j ACCEPT #允许所有本机向外的访问
iptables -A INPUT -p tcp --dport 22 -j ACCEPT #允许访问22端口
iptables -A INPUT -p tcp --dport 80 -j ACCEPT #允许访问80端口
iptables -A INPUT -p tcp --dport 21 -j ACCEPT #允许ftp服务的21端口
iptables -A INPUT -p tcp --dport 20 -j ACCEPT #允许FTP服务的20端口
iptables -A INPUT -j reject #禁止其他未允许的规则访问
iptables -A FORWARD -j REJECT #禁止其他未允许的规则访问
# 屏蔽IP
iptables -A INPUT -p tcp -m tcp -s 192.168.0.8 -j DROP # 屏蔽恶意主机（比如，192.168.0.8
iptables -I INPUT -s 123.45.6.7 -j DROP # 屏蔽单个IP的命令
iptables -I INPUT -s 123.0.0.0/8 -j DROP # 封整个段即从123.0.0.1到123.255.255.254的命令
iptables -I INPUT -s 124.45.0.0/16 -j DROP # 封IP段即从123.45.0.1到123.45.255.254的命令
iptables -I INPUT -s 123.45.6.0/24 -j DROP # 封IP段即从123.45.6.1到123.45.6.254的命令是
# 指定数据包出去的网络接口
## 只对 OUTPUT，FORWARD，POSTROUTING 三个链起作用。
iptables -A FORWARD -o eth0
# 查看已添加的规则
iptables -L -n -v
Chain INPUT (policy DROP 48106 packets, 2690K bytes)
pkts bytes target prot opt in out source destination
5075 589K ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
191K 90M ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:22
1499K 133M ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:80
4364K 6351M ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
6256 327K ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 3382K packets, 1819M bytes)
pkts bytes target prot opt in out source destination
5075 589K ACCEPT all -- * lo 0.0.0.0/0 0.0.0.0/0
# 启动网络转发规则
## 公网`210.14.67.7`让内网`192.168.188.0/24`上网
iptables -t nat -A POSTROUTING -s 192.168.188.0/24 -j SNAT --to-source 210.14.67.127
# 端口映射
## 本机的2222端口映射到内网 虚拟机的22端口
iptables -t nat -A PREROUTING -d 210.14.67.127 -p tcp --dport 2222 -j DNAT --to-dest 192.168.188.115:22
# 字符串匹配
## 比如，我们要过滤所有TCP连接中的字符串`test`，一旦出现它我们就终止这个连接，我们可以这么做：
iptables -A INPUT -p tcp -m string --algo kmp --string "test" -j REJECT --reject-with tcp-reset
iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
REJECT tcp -- anywhere anywhere STRING match "test" ALGO name kmp TO 65535 reject-with tcp-reset
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
# 阻止Windows蠕虫的攻击
iptables -I INPUT -j DROP -p tcp -s 0.0.0.0/0 -m string --algo kmp --string "cmd.exe"
# 防止SYN洪水攻击
iptables -A INPUT -p tcp --syn -m limit --limit 5/second -j ACCEPT
# 添加SECMARK记录
iptables -t mangle -A INPUT -p tcp --src 192.168.1.2 --dport 443 -j SECMARK --selctx system_u:object_r:myauth_packet_t
# 向从 192.168.1.2:443 以TCP方式发出到本机的包添加MAC安全上下文 system_u:object_r:myauth_packet_t
# 允许内网访问28000~30000之间的端口
iptables -A INPUT -s 192.168.1.0/24 -p tcp --dport 28000:30000 -j ACCEPT
附录
iptables常用主选项
配置示例
k8s-master01
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy DROP)
target prot opt source destination
DOCKER-USER all -- anywhere anywhere
DOCKER-ISOLATION-STAGE-1 all -- anywhere anywhere
ACCEPT all -- anywhere anywhere ctstate RELATED,ESTABLISHED
DOCKER all -- anywhere anywhere
ACCEPT all -- anywhere anywhere
ACCEPT all -- anywhere anywhere
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Chain DOCKER (1 references)
target prot opt source destination
Chain DOCKER-ISOLATION-STAGE-1 (1 references)
target prot opt source destination
DOCKER-ISOLATION-STAGE-2 all -- anywhere anywhere
RETURN all -- anywhere anywhere
Chain DOCKER-ISOLATION-STAGE-2 (1 references)
target prot opt source destination
DROP all -- anywhere anywhere
RETURN all -- anywhere anywhere
Chain DOCKER-USER (1 references)
target prot opt source destination
RETURN all -- anywhere anywhere
k8s-master02
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
k8s-master03
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
k8s-node06
Chain INPUT (policy ACCEPT)
target prot opt source destination
cali-INPUT all -- anywhere anywhere /* cali:Cz_u1IQiXIMmKD4c */
KUBE-FIREWALL all -- anywhere anywhere
KUBE-NODE-PORT all -- anywhere anywhere /* kubernetes health check rules */
Chain FORWARD (policy ACCEPT)
target prot opt source destination
cali-FORWARD all -- anywhere anywhere /* cali:wUHhoiAYhphO9Mso */
DOCKER-USER all -- anywhere anywhere
DOCKER-ISOLATION-STAGE-1 all -- anywhere anywhere
ACCEPT all -- anywhere anywhere ctstate RELATED,ESTABLISHED
DOCKER all -- anywhere anywhere
ACCEPT all -- anywhere anywhere
ACCEPT all -- anywhere anywhere
KUBE-FORWARD all -- anywhere anywhere /* kubernetes forwarding rules */
ACCEPT all -- anywhere anywhere /* cali:S93hcgKJrXEqnTfs */ /* Policy explicitly accepted packet. */ mark match 0x10000/0x10000
MARK all -- anywhere anywhere /* cali:mp77cMpurHhyjLrM */ MARK or 0x10000
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
cali-OUTPUT all -- anywhere anywhere /* cali:tVnHkvAo15HuiPy0 */
KUBE-FIREWALL all -- anywhere anywhere
Chain KUBE-FORWARD (1 references)
target prot opt source destination
ACCEPT all -- anywhere anywhere mark match 0x4000/0x4000 /* kubernetes forwarding rules */
ACCEPT all -- anywhere anywhere ctstate RELATED,ESTABLISHED /* kubernetes forwarding conntrack pod source rule */
ACCEPT all -- anywhere anywhere ctstate RELATED,ESTABLISHED /* kubernetes forwarding conntrack pod destination rule */
Chain KUBE-NODE-PORT (1 references)
target prot opt source destination
ACCEPT all -- anywhere anywhere match-set KUBE-HEALTH-CHECK-NODE-PORT dst /* Kubernetes health check node port */
Chain DOCKER (1 references)
target prot opt source destination
Chain DOCKER-ISOLATION-STAGE-1 (1 references)
target prot opt source destination
DOCKER-ISOLATION-STAGE-2 all -- anywhere anywhere
RETURN all -- anywhere anywhere
Chain DOCKER-ISOLATION-STAGE-2 (1 references)
target prot opt source destination
DROP all -- anywhere anywhere
RETURN all -- anywhere anywhere
Chain DOCKER-USER (1 references)
target prot opt source destination
RETURN all -- anywhere anywhere
Chain KUBE-FIREWALL (2 references)
target prot opt source destination
DROP all -- anywhere anywhere mark match 0x8000/0x8000 /* kubernetes firewall for dropping marked packets */
DROP all -- !127.0.0.0/8 127.0.0.0/8 ! ctstate RELATED,ESTABLISHED,DNAT /* block incoming localnet connections */
DROP all -- anywhere anywhere mark match 0x8000/0x8000 /* kubernetes firewall for dropping marked packets */
DROP all -- !127.0.0.0/8 127.0.0.0/8 ! ctstate RELATED,ESTABLISHED,DNAT /* block incoming localnet connections */
Chain KUBE-KUBELET-CANARY (0 references)
target prot opt source destination
Chain cali-to-wl-dispatch (2 references)
target prot opt source destination
DROP all -- anywhere anywhere /* cali:7KNphB1nNHw80nIO */ /* Unknown interface */
Chain cali-OUTPUT (1 references)
target prot opt source destination
ACCEPT all -- anywhere anywhere /* cali:Mq1_rAdXXH3YkrzW */ mark match 0x10000/0x10000
cali-forward-endpoint-mark all -- anywhere anywhere [goto] /* cali:5Z67OUUpTOM7Xa1a */ mark match ! 0x0/0xfff00000
RETURN all -- anywhere anywhere /* cali:M2Wf0OehNdig8MHR */
ACCEPT ipencap-- anywhere anywhere /* cali:AJBkLho_0Qd8LNr3 */ /* Allow IPIP packets to other Calico hosts */ match-set cali40all-hosts-net dst ADDRTYPE match src-type LOCAL
MARK all -- anywhere anywhere /* cali:iz2RWXlXJDUfsLpe */ MARK and 0xfff0ffff
cali-to-host-endpoint all -- anywhere anywhere /* cali:xQqLi8S0sxbiyvjR */ ! ctstate DNAT
ACCEPT all -- anywhere anywhere /* cali:aSnsxZdmhxm_ilRZ */ /* Host endpoint policy accepted packet. */ mark match 0x10000/0x10000
Chain cali-to-hep-forward (2 references)
target prot opt source destination
Chain cali-INPUT (1 references)
target prot opt source destination
ACCEPT ipencap-- anywhere anywhere /* cali:PajejrV4aFdkZojI */ /* Allow IPIP packets from Calico hosts */ match-set cali40all-hosts-net src ADDRTYPE match dst-type LOCAL
DROP ipencap-- anywhere anywhere /* cali:_wjq-Yrma8Ly1Svo */ /* Drop IPIP packets from non-Calico hosts */
MARK all -- anywhere anywhere /* cali:ss8lEMQsXi-s6qYT */ MARK and 0xfffff
cali-forward-check all -- anywhere anywhere /* cali:PgIW-V0nEjwPhF_8 */
RETURN all -- anywhere anywhere /* cali:QMJlDwlS0OjHyfMN */ mark match ! 0x0/0xfff00000
cali-wl-to-host all -- anywhere anywhere [goto] /* cali:nDRe73txrna-aZjG */
ACCEPT all -- anywhere anywhere /* cali:iX2AYvqGXaVqwkro */ mark match 0x10000/0x10000
MARK all -- anywhere anywhere /* cali:bhpnxD5IRtBP8KW0 */ MARK and 0xfff0ffff
cali-from-host-endpoint all -- anywhere anywhere /* cali:H5_bccAbHV0sooVy */
ACCEPT all -- anywhere anywhere /* cali:inBL01YlfurT0dbI */ /* Host endpoint policy accepted packet. */ mark match 0x10000/0x10000
Chain cali-from-hep-forward (1 references)
target prot opt source destination
Chain cali-cidr-block (1 references)
target prot opt source destination
Chain cali-forward-endpoint-mark (1 references)
target prot opt source destination
cali-from-endpoint-mark all -- anywhere anywhere /* cali:O0SmFDrnm7KggWqW */ mark match ! 0x100000/0xfff00000
cali-to-wl-dispatch all -- anywhere anywhere /* cali:aFl0WFKRxDqj8oA6 */
cali-to-hep-forward all -- anywhere anywhere /* cali:AZKVrO3i_8cLai5f */
MARK all -- anywhere anywhere /* cali:96HaP1sFtb-NYoYA */ MARK and 0xfffff
ACCEPT all -- anywhere anywhere /* cali:VxO6hyNWz62YEtul */ /* Policy explicitly accepted packet. */ mark match 0x10000/0x10000
Chain cali-from-wl-dispatch (2 references)
target prot opt source destination
DROP all -- anywhere anywhere /* cali:zTj6P0TIgYvgz-md */ /* Unknown interface */
Chain cali-forward-check (1 references)
target prot opt source destination
RETURN all -- anywhere anywhere /* cali:Pbldlb4FaULvpdD8 */ ctstate RELATED,ESTABLISHED
cali-set-endpoint-mark tcp -- anywhere anywhere [goto] /* cali:ZD-6UxuUtGW-xtzg */ /* To kubernetes NodePort service */ multiport dports 30000:32767 match-set cali40this-host dst
cali-set-endpoint-mark udp -- anywhere anywhere [goto] /* cali:CbPfUajQ2bFVnDq4 */ /* To kubernetes NodePort service */ multiport dports 30000:32767 match-set cali40this-host dst
cali-set-endpoint-mark all -- anywhere anywhere /* cali:jmhU0ODogX-Zfe5g */ /* To kubernetes service */ ! match-set cali40this-host dst
Chain cali-set-endpoint-mark (3 references)
target prot opt source destination
DROP all -- anywhere anywhere /* cali:MN61lcxFj1yWuYBo */ /* Unknown endpoint */
MARK all -- anywhere anywhere /* cali:nKOjq8N2yzfmS3jk */ /* Non-Cali endpoint mark */ MARK xset 0x100000/0xfff00000
Chain cali-from-endpoint-mark (1 references)
target prot opt source destination
DROP all -- anywhere anywhere /* cali:9dpftzl-pNycbr37 */ /* Unknown interface */
Chain cali-from-host-endpoint (1 references)
target prot opt source destination
Chain cali-wl-to-host (1 references)
target prot opt source destination
cali-from-wl-dispatch all -- anywhere anywhere /* cali:Ee9Sbo10IpVujdIY */
ACCEPT all -- anywhere anywhere /* cali:nSZbcOoG1xPONxb8 */ /* Configured DefaultEndpointToHostAction */
Chain cali-to-host-endpoint (1 references)
target prot opt source destination
Chain cali-FORWARD (1 references)
target prot opt source destination
MARK all -- anywhere anywhere /* cali:vjrMJCRpqwy5oRoX */ MARK and 0xfff1ffff
cali-from-hep-forward all -- anywhere anywhere /* cali:A_sPAO0mcxbT9mOV */ mark match 0x0/0x10000
cali-from-wl-dispatch all -- anywhere anywhere /* cali:8ZoYfO5HKXWbB3pk */
cali-to-wl-dispatch all -- anywhere anywhere /* cali:jdEuaPBe14V2hutn */
cali-to-hep-forward all -- anywhere anywhere /* cali:12bc6HljsMKsmfr- */
cali-cidr-block all -- anywhere anywhere /* cali:NOSxoaGx8OIstr1z */