iptables的基本参数和简单使用方法

规则链与策略:

规则:

ACCEPT：允许通过

LOG：记录日志

REJECT：拒绝通过，给出返回值

DROP：丢弃

规则链:

PREROUTING：路由前处理

INPUT：处理入站数据

OUTPUT：处理出站数据

FORWARD：处理转发数据

POSTROUTING：路由后处理

raw表：确定是否对数据包状态跟踪

mangle表：设置标记

nat表：修改数据包源、目标IP或端口

filter表：过滤

规则顺序

规则表先后顺序：raw表→mangle表→nat表→filter表

规则链先后顺序：

入站：PREROUTING→INPUT

出站：OUTPUT→POSTROUTING

转发：PREROUTING→FORWARD→POSTROUTING

基本参数：

iptables [-t 表名] 选项 [链名] [条件] [控制类型]

Usage: iptables -[ACD] chain rule-specification [options]
iptables -I chain [rulenum] rule-specification [options]
iptables -R chain rulenum rule-specification [options]
iptables -D chain rulenum [options]
iptables -[LS] [chain [rulenum]] [options]
iptables -[FZ] [chain] [options]
iptables -[NX] chain
iptables -E old-chain-name new-chain-name
iptables -P chain target [options]
iptables -h (print this help information)

Commands:
Either long or short options are allowed.
--append  -A chain            Append to chain
--check   -C chain            Check for the existence of a rule
--delete  -D chain            Delete matching rule from chain
--delete  -D chain rulenum
Delete rule rulenum (1 = first) from chain
--insert  -I chain [rulenum]
Insert in chain as rulenum (default 1=first)
--replace -R chain rulenum
Replace rule rulenum (1 = first) in chain
--list    -L [chain [rulenum]]
List the rules in a chain or all chains
--list-rules -S [chain [rulenum]]
Print the rules in a chain or all chains
--flush   -F [chain]          Delete all rules in  chain or all chains
--zero    -Z [chain [rulenum]]
Zero counters in chain or all chains
--new     -N chain            Create a new user-defined chain
--delete-chain
-X [chain]          Delete a user-defined chain
--policy  -P chain target
Change policy on chain to target
--rename-chain
-E old-chain new-chain
Change chain name, (moving any references)
Options:
--ipv4      -4              Nothing (line is ignored by ip6tables-restore)
--ipv6      -6              Error (line is ignored by iptables-restore)
[!] --protocol  -p proto        protocol: by number or name, eg. `tcp'
[!] --source    -s address[/mask][...]
source specification
[!] --destination -d address[/mask][...]
destination specification
[!] --in-interface -i input name[+]
network interface name ([+] for wildcard)
--jump -j target
target for rule (may load target extension)
--goto      -g chain
jump to chain with no return
--match       -m match
extended match (may load extension)
--numeric     -n              numeric output of addresses and ports
[!] --out-interface -o output name[+]
network interface name ([+] for wildcard)
--table       -t table        table to manipulate (default: `filter')
--verbose     -v              verbose mode
--wait        -w              wait for the xtables lock
--line-numbers                print line numbers when listing
--exact       -x              expand numbers (display exact values)
[!] --fragment  -f              match second or further fragments only
--modprobe=<command>          try to insert modules using this command
--set-counters PKTS BYTES     set the counter during insert/append
[!] --version   -V              print package version.

基本使用方法：

查看已有规则：

iptables -L

清空所有规则：

iptables -F

拒绝INPUT

iptables -P INPUT DROP

允许所有ping：

iptables -I INPUT -p icmp -j ACCEPT

在末尾加入允许未被其他规则匹配的数据包：

iptables -t filter -A INPUT -j -ACCEPT

删除INPUT第二条规则：

iptables -D INPUT 2

仅允许来自172.27.8.0/22的用户连接ssh服务

iptables -I INPUT -s 172.27.8.0/22 -p tcp --dport 22 -j ACCEPT

iptables -A INPUT -p tcp  --dport 22 -j REJECT

不允许任何用户访问本机3306端口

iptables -I INPUT -p tcp --dport 3306 -j REJECT

iptables -I INPUT -p udp --dport 3306 -j REJECT

拒绝其他用户通过网卡eth1访问本机http服务

iptables -I INPUT -i eth1 -p tcp --dport 80 -j REJECT

禁止用户访问www.baidu.com

iptables -I FORWARD -d www.baidu.com -j DROP

禁止172.27.8.22的用户上网

iptables -I  FORWARD -s 172.27.8.22 -j DROP

流量均衡：

将访问流量分流至内网三台不同主机：

iptables -A PREROUTING -i eth1 -p tcp --dport 80 -m state --state NEW -m nth --counter 0 --every 3 --packet 0 -j DNAT -to-destination 172.27.8.10
iptables -A PREROUTING -i eth1 -p tcp --dport 80 -m state --state NEW -m nth --counter 0 --every 3 --packet 0 -j DNAT -to-destination 172.27.8.20
iptables -A PREROUTING -i eth1 -p tcp --dport 80 -m state --state NEW -m nth --counter 0 --every 3 --packet 0 -j DNAT -to-destination 172.27.8.30

使用上述操作，规则仅当前有效，如需重启依然有效，执行service iptables save 将规则写入/etc/sysconfig/iptables中

顺便再贴一个iptables配置：

# Generated by iptables-save v1.4.7 on Thu Apr 16 01:33:03 2015
*filter
:INPUT DROP [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
#允许本机回环地址
-A INPUT -i lo -p all -j ACCEPT
##允许这些IP所有操作
-A INPUT -s 110.122.120.54/32 -j ACCEPT
-A INPUT -s 110.122.120.98/32 -j ACCEPT
##允许DNS解析
-A INPUT -p udp --sport 53 -j ACCEPT
#允许5672端口访问
-A INPUT -s 10.10.2.160 -p tcp --sport 5672 -j ACCEPT
##禁止eth0上27017入站和出站
-A INPUT -i eth0  -p tcp --dport 27017 -j DROP
-A OUTPUT -o eth0 -p tcp --sport 27017 -j DROP
##允许zabbix的10050端口
-A INPUT -s 100.10.2.160 -p tcp --dport 10050 -j ACCEPT
##运许snmp的161端口
-A INPUT -s 100.10.2.160 -p tcp --dport 10050 -j ACCEPT
##允许程序主机访问指定IP的4506端口
-A INPUT -s 172.27.1.75 -p tcp --dport 4506 -j ACCEPT
##允许下列端口访问
-A INPUT -p tcp --dport 8080 -j ACCEPT
-A INPUT -p tcp --dport 8090 -j ACCEPT
-A INPUT -p tcp --dport 13000 -j ACCEPT
-A INPUT -p tcp --dport 9000 -j ACCEPT
-A INPUT -p tcp --dport 8888 -j ACCEPT
COMMIT