Linux防火墙之iptables基本匹配条件和隐式扩展匹配条件

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发表文章数:4263

深入理解JDK中的Reference原理和源码实现

一、iptables的基本匹配条件

  上一篇博文我们说到了iptables的基本工作原理、数据报文在内核的走向和管理链、管理规则、以及查看规则、导入和导出规则;回顾请参考https://www.cnblogs.com/qiuhom-1874/p/12237976.html,今天我们再来说说iptables的基本匹配条件。

  iptables的基本匹配条件也叫通用匹配条件,是iptables/netfilter原生自带的,无需加载模块,通俗的讲就是iptables这个命令的原生选项。iptables基本匹配条件有以下几种

  1、[!] -s,–source addresss[/mask][,…]:表示匹配报文段源ip地址或范围,它可以是一个ip地址,也可以是一个网段地址,网段地址需要写明子网掩码,其中子网掩码支持225.255.0.0的方式,也支持数字表示,比如192.168.0.0/24。同时它也支持取反。

[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
  461 33551 ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp dpt:41319
  134 11256 ACCEPT     icmp --  *      *       0.0.0.0/0            192.168.0.99         icmptype 8

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 14 packets, 1320 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  *      *       192.168.0.99         0.0.0.0/0            tcp spt:53
  134 11256 ACCEPT     icmp --  *      *       192.168.0.99         0.0.0.0/0            icmptype 0

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
[root@test ~]# iptables -A my_chain -s 192.168.1.0/24 -j ACCEPT
[root@test ~]# iptables -A my_chain -s 192.168.0.232 -d 192.168.0.99 -j ACCEPT
[root@test ~]# iptables -A my_chain -s 192.168.0.0/255.255.255.0 -j ACCEPT
[root@test ~]# iptables -nvL my_chain
Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     all  --  *      *       192.168.1.0/24       0.0.0.0/0           
    0     0 ACCEPT     all  --  *      *       192.168.0.232        192.168.0.99        
    0     0 ACCEPT     all  --  *      *       192.168.0.0/24       0.0.0.0/0           
[root@test ~]# iptables -A my_chain ! -s 192.168.10.0/24 -j ACCEPT
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
  946 67475 ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp dpt:41319
  134 11256 ACCEPT     icmp --  *      *       0.0.0.0/0            192.168.0.99         icmptype 8

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 15 packets, 1396 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  *      *       192.168.0.99         0.0.0.0/0            tcp spt:53
  134 11256 ACCEPT     icmp --  *      *       192.168.0.99         0.0.0.0/0            icmptype 0

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     all  --  *      *       192.168.1.0/24       0.0.0.0/0           
    0     0 ACCEPT     all  --  *      *       192.168.0.232        192.168.0.99        
    0     0 ACCEPT     all  --  *      *       192.168.0.0/24       0.0.0.0/0           
    0     0 ACCEPT     all  --  *      *      !192.168.10.0/24      0.0.0.0/0           
[root@test ~]# 

  2、-d,–destination address[/mask][,…]:表示匹配报文的目标ip地址或范围,它同-s的用法一样,支持单台主机或一个网段,网段需写明子网掩码,子网掩码支持数字表示,也支持子网掩码地址的方式表示。同时它也支持对匹配的条件取反。

[root@test ~]# iptables -F my_chain
[root@test ~]# iptables -nvL my_chain
Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
[root@test ~]# iptables -A my_chain -d 192.168.0.99 -p tcp --dport 22 -j ACCEPT
[root@test ~]# iptables -A my_chain -d 192.168.0.10 -p tcp --dport 3306 -j DROP
[root@test ~]# iptables -A my_chain -d 192.168.10.0/24 -p tcp --dport 25 -j DROP          
[root@test ~]# iptables -A my_chain ! -d 192.168.11.0/255.255.255.0 -p tcp --dport 123 -j DROP     
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
 1698  123K ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp dpt:41319
  134 11256 ACCEPT     icmp --  *      *       0.0.0.0/0            192.168.0.99         icmptype 8

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 17 packets, 1580 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  *      *       192.168.0.99         0.0.0.0/0            tcp spt:53
  134 11256 ACCEPT     icmp --  *      *       192.168.0.99         0.0.0.0/0            icmptype 0

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp dpt:22
    0     0 DROP       tcp  --  *      *       0.0.0.0/0            192.168.0.10         tcp dpt:3306
    0     0 DROP       tcp  --  *      *       0.0.0.0/0            192.168.10.0/24      tcp dpt:25
    0     0 DROP       tcp  --  *      *       0.0.0.0/0           !192.168.11.0/24      tcp dpt:123
[root@test ~]# 

  3、[!] -p, –protocol protocol:指定协议,可使用数字如0(all);protocol: tcp, udp, icmp, icmpv6, udplite,esp, ah, sctp, mh or“all“ 参考:/etc/protocols

[root@test ~]# iptables -F my_chain 
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
 1752  126K ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp dpt:41319
  134 11256 ACCEPT     icmp --  *      *       0.0.0.0/0            192.168.0.99         icmptype 8

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 13 packets, 1212 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  *      *       192.168.0.99         0.0.0.0/0            tcp spt:53
  134 11256 ACCEPT     icmp --  *      *       192.168.0.99         0.0.0.0/0            icmptype 0

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
[root@test ~]# iptables -A my_chain -s 192.168.0.232 -d 192.168.0.99 -p tcp --dport 80 -j DROP
[root@test ~]# iptables -A my_chain -s 192.168.0.232 -d 192.168.0.99 -p tcp --dport 23 -j DROP
[root@test ~]# iptables -A my_chain -d 192.168.0.99 -p tcp --sport 25 -j ACCEPT
[root@test ~]# iptables -A my_chain -d 192.168.0.99 -p icmp --icmp-type 0 -j ACCEPT
[root@test ~]# iptables -A my_chain  -s 192.168.0.232 -d 192.168.0.99 -p icmp --icmp-type 8 -j ACCEPT
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
 2487  179K ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp dpt:41319
  134 11256 ACCEPT     icmp --  *      *       0.0.0.0/0            192.168.0.99         icmptype 8

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 47 packets, 4340 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  *      *       192.168.0.99         0.0.0.0/0            tcp spt:53
  134 11256 ACCEPT     icmp --  *      *       192.168.0.99         0.0.0.0/0            icmptype 0

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 DROP       tcp  --  *      *       192.168.0.232        192.168.0.99         tcp dpt:80
    0     0 DROP       tcp  --  *      *       192.168.0.232        192.168.0.99         tcp dpt:23
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp spt:25
    0     0 ACCEPT     icmp --  *      *       0.0.0.0/0            192.168.0.99         icmptype 0
    0     0 ACCEPT     icmp --  *      *       192.168.0.232        192.168.0.99         icmptype 8
[root@test ~]# iptables -A my_chain  ! -p udp -j ACCEPT
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
 2586  186K ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp dpt:41319
  134 11256 ACCEPT     icmp --  *      *       0.0.0.0/0            192.168.0.99         icmptype 8

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 13 packets, 1212 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  *      *       192.168.0.99         0.0.0.0/0            tcp spt:53
  134 11256 ACCEPT     icmp --  *      *       192.168.0.99         0.0.0.0/0            icmptype 0

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 DROP       tcp  --  *      *       192.168.0.232        192.168.0.99         tcp dpt:80
    0     0 DROP       tcp  --  *      *       192.168.0.232        192.168.0.99         tcp dpt:23
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp spt:25
    0     0 ACCEPT     icmp --  *      *       0.0.0.0/0            192.168.0.99         icmptype 0
    0     0 ACCEPT     icmp --  *      *       192.168.0.232        192.168.0.99         icmptype 8
    0     0 ACCEPT    !udp  --  *      *       0.0.0.0/0            0.0.0.0/0           
[root@test ~]# 

  提示:-p指定某一协议时,往往会有该协议的一些隐式扩展的选项,比如我们指定-p tcp 表示指定协议类型为tcp 后面指定的源端口或者目标端口 就是tcp模块的隐式。通俗讲就是我们指定了协议为tcp 可以不用明确的用-m 再指定其模块,这种机制我们叫隐式扩展。上面的例子用到了隐式扩展到有 tcp 的 –sport –dport ;icmp 协议的–icmp-type;当然-p指定协议的类型也可以用! 来对它取反,表示匹配除了指定的协议以为的所有协议的报文,如果不用-p 指定协议表示匹配所有协议的报文

  4、[!] -i, –in-interface name:报文流入的接口;只能应用于数据报文流入环节,只应用于INPUT、FORWARD、PREROUTING链以及自定义链。

[root@test ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:30:18:51:af:3c brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.99/24 brd 192.168.0.255 scope global noprefixroute enp2s0
       valid_lft forever preferred_lft forever
    inet 172.16.1.2/16 brd 172.16.255.255 scope global noprefixroute enp2s0:0
       valid_lft forever preferred_lft forever
    inet6 fe80::230:18ff:fe51:af3c/64 scope link 
       valid_lft forever preferred_lft forever
3: enp3s0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
    link/ether 00:30:18:51:af:3d brd ff:ff:ff:ff:ff:ff
4: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default 
    link/ether 02:42:63:ab:82:55 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 scope global docker0
       valid_lft forever preferred_lft forever
[root@test ~]# iptables -F my_chain 
[root@test ~]# iptables -nvL my_chain 
Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
[root@test ~]# iptables -A my_chain  -s 192.168.0.0/24 -i enp2s0 -j ACCEPT
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
 2911  209K ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp dpt:41319
  134 11256 ACCEPT     icmp --  *      *       0.0.0.0/0            192.168.0.99         icmptype 8

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 13 packets, 1212 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  *      *       192.168.0.99         0.0.0.0/0            tcp spt:53
  134 11256 ACCEPT     icmp --  *      *       192.168.0.99         0.0.0.0/0            icmptype 0

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     all  --  enp2s0 *       192.168.0.0/24       0.0.0.0/0           
[root@test ~]# iptables -A OUTPUT  -i enp2s0 -j ACCEPT
iptables v1.4.21: Can't use -i with OUTPUT

Try `iptables -h' or 'iptables --help' for more information.
[root@test ~]# 

  提示:自定义添加到规则可以被任意主链所引用。不存在自定义链上的规则不适用主链,但主链上可以引用它的,只是说主链引用后,规则不生效,匹配不到报文。-i 表示指定网络报文流入的接口,所以这个基本匹配条件,只能用于报文能够进来的链上,比如PREROUTING、INPUT、FORWARD这三个主链,以及自定义链,通常情况,如果写到自定义链,都是被这三个主链所引用,除此之外,被OUTPUT、和POSTROUTING所引用,规则是无效的,不能匹配到报文。

  5、[!] -o, –out-interface name:报文流出的接口;只能应用于数据报文流出的环节,只应用于FORWARD、OUTPUT、POSTROUTING链以及自定义链

[root@test ~]# ip a s 
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:30:18:51:af:3c brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.99/24 brd 192.168.0.255 scope global noprefixroute enp2s0
       valid_lft forever preferred_lft forever
    inet 172.16.1.2/16 brd 172.16.255.255 scope global noprefixroute enp2s0:0
       valid_lft forever preferred_lft forever
    inet6 fe80::230:18ff:fe51:af3c/64 scope link 
       valid_lft forever preferred_lft forever
3: enp3s0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
    link/ether 00:30:18:51:af:3d brd ff:ff:ff:ff:ff:ff
4: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default 
    link/ether 02:42:63:ab:82:55 brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 scope global docker0
       valid_lft forever preferred_lft forever
[root@test ~]# iptables -F my_chain 
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
   66  4512 ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp dpt:41319
    0     0 ACCEPT     icmp --  *      *       0.0.0.0/0            192.168.0.99         icmptype 8

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 13 packets, 1212 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     icmp --  *      *       192.168.0.99         0.0.0.0/0            icmptype 0

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
[root@test ~]# iptables -A my_chain  -o enp2s0 -j ACCEPT
[root@test ~]# iptables -A INPUT -o enp2s0 -j DROP
iptables v1.4.21: Can't use -o with INPUT

Try `iptables -h' or 'iptables --help' for more information.
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
  238 16280 ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp dpt:41319
    0     0 ACCEPT     icmp --  *      *       0.0.0.0/0            192.168.0.99         icmptype 8

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 61 packets, 5724 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     icmp --  *      *       192.168.0.99         0.0.0.0/0            icmptype 0

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     all  --  *      enp2s0  0.0.0.0/0            0.0.0.0/0           
[root@test ~]# 

  提示:同样-o表示匹配网络报文的出口接口,不能用于网络报文入口的链上。在iptables/netfilter框架中,报文的出口只经过FORWARD、OUTPUT和POSTROUTING这三个主链,即便我们在自定义链上用-o来指定匹配出口的网络接口,也只有被FORWARD、OUTPUT或者POSTROUTING这三个主链所引用才能生效,匹配到报文,用在INPUT或PREROUTING链上iptables是不允许的。可以看到FORWARD这个链上即可以匹配网络报文的入口接口和出口接口。

二、tcp/udp/icmp隐式扩展选项说明

  iptables的匹配条件分基本匹配条件和扩展匹配条件,扩展匹配条件里有显示扩展和隐式扩展,从字面上很好理解,显示就是明确指定嘛 ,隐式就是不明确指定,通常扩展匹配条件是需要加载扩展模块(/usr/lib64/xtables/*.so)方可生效;隐式扩展我们可以理解为,当我们使用-p 去指定协议时无需再用-m再指定其模块,就可以使用其扩展模块中的选项,也就是说不需要我们手动的去加载模块,-p 所指定的协议,会帮我们加载。(这个仅个人理解哈)

  1、tcp协议的隐式扩展选项说明

    [!] –source-port, –sport port[:port]:匹配报文源端口,可为端口范围,当端口连续时可以用:来表示;比如21:25,表示匹配21,22,23,24,25这些连续的端口。

[root@test ~]# iptables -F my_chain 
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
  878 58520 ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp dpt:41319
    0     0 ACCEPT     icmp --  *      *       0.0.0.0/0            192.168.0.99         icmptype 8

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 13 packets, 1212 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     icmp --  *      *       192.168.0.99         0.0.0.0/0            icmptype 0

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
[root@test ~]# iptables -A my_chain  -s 192.168.0.232 -d 192.168.0.99 -p tcp --sport 22 -j ACCEPT
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
 1324 93312 ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp dpt:41319
    0     0 ACCEPT     icmp --  *      *       0.0.0.0/0            192.168.0.99         icmptype 8

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 34 packets, 3144 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     icmp --  *      *       192.168.0.99         0.0.0.0/0            icmptype 0

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  *      *       192.168.0.232        192.168.0.99         tcp spt:22
[root@test ~]# 

  提示:以上添加到规则表示匹配源地址为192.168.0.232 目标地址为192.168.0.99 的tcp报文,并且源端口为22 的报文,如果匹配到这样的报文,给予放行操作。当然如果是匹配一个连续的端口可以写成:来表示中间连续的端口,它也支持对源端口取反,表示匹配除了指定的端口以外的所有端口如下所示

[root@test ~]# iptables -A my_chain  -s 192.168.0.232 -d 192.168.0.99 -p tcp --sport 23:30 -j ACCEPT   
[root@test ~]# iptables -nvL my_chain 
Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  *      *       192.168.0.232        192.168.0.99         tcp spt:22
    0     0 ACCEPT     tcp  --  *      *       192.168.0.232        192.168.0.99         tcp spts:23:30
[root@test ~]# iptables -A my_chain  -s 192.168.0.232 -d 192.168.0.99 -p tcp ! --sport 40:50 -j ACCEPT     
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
 1519  107K ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp dpt:41319
    0     0 ACCEPT     icmp --  *      *       0.0.0.0/0            192.168.0.99         icmptype 8

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 13 packets, 1212 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     icmp --  *      *       192.168.0.99         0.0.0.0/0            icmptype 0

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  *      *       192.168.0.232        192.168.0.99         tcp spt:22
    0     0 ACCEPT     tcp  --  *      *       192.168.0.232        192.168.0.99         tcp spts:23:30
    0     0 ACCEPT     tcp  --  *      *       192.168.0.232        192.168.0.99         tcp spts:!40:50
[root@test ~]# 

  [!] –destination-port,–dport port[:port]:匹配报文目标端口,可为范围,当端口连续是也可以用:来代替连续中间的端口,同–sport用法一样

[root@test ~]# iptables -F
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 19 packets, 1332 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 13 packets, 1212 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
[root@test ~]# iptables -A my_chain  -d 192.168.0.99 -p tcp --dport 22 -j ACCEPT
[root@test ~]# iptables -A my_chain  -d 192.168.0.99 -p tcp --dport 23:25 -j ACCEPT 
[root@test ~]# iptables -A my_chain  -d 192.168.0.99 -p tcp ! --dport 80 -j ACCEPT     
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 19 packets, 1332 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 13 packets, 1212 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp dpt:22
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp dpts:23:25
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            192.168.0.99         tcp dpt:!80
[root@test ~]# 

  [!] –tcp-flags mask comp表示匹配符合指定标志的数据报文,mask表示需检查的标志为列表,用逗号分隔,例如SYN,ACK,FIN,RST;comp表示mask列表中必须为1的标志为列表,没有指定表示必须为0用逗号分隔

混沌工程-初识

[root@test ~]# iptables -F
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 22 packets, 1556 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 15 packets, 1396 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
[root@test ~]# iptables -A my_chain  -p tcp --tcp-flags SYN,ACK,FIN,RST SYN -j ACCEPT
[root@test ~]# iptables -A my_chain  -p tcp --tcp-flags ALL ALL -j DROP
[root@test ~]# iptables -A my_chain  -p tcp --tcp-flags ALL NONE -j DROP   
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 47 packets, 3830 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 39 packets, 3630 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp flags:0x17/0x02
    0     0 DROP       tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp flags:0x3F/0x3F
    0     0 DROP       tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp flags:0x3F/0x00
[root@test ~]# 

  提示:以上规则表示匹配tcp报文,syn=1 其他标志位为0的报文给予允许放行,匹配所有标志位为1的报文给予丢弃,匹配到所有标志为0的报文给予丢弃。这个扩展选项也支持取反,表示出了指定的标志位的所有报文。

  [!] –syn:用于匹配TCP第一次握手报文,它相当于–tcp-flags SYN,ACK,FIN,RST SYN

[root@test ~]# iptables -nvL 
Chain INPUT (policy ACCEPT 73 packets, 5582 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 61 packets, 6538 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp flags:0x17/0x02
    0     0 DROP       tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp flags:0x3F/0x3F
    0     0 DROP       tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp flags:0x3F/0x00
[root@test ~]# iptables -A INPUT  -p tcp --syn -j ACCEPT
[root@test ~]# iptables -nvL 
Chain INPUT (policy ACCEPT 11 packets, 804 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp flags:0x17/0x02

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 8 packets, 864 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp flags:0x17/0x02
    0     0 DROP       tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp flags:0x3F/0x3F
    0     0 DROP       tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp flags:0x3F/0x00
[root@test ~]# 

  2、udp协议的隐式扩展选项说明

  [!] –source-port, –sport port[:port]:匹配报文的源端口或端口范围,当端口连续可以使用:来代替连续的中间端口

[root@test ~]# iptables -F
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 24 packets, 1636 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 15 packets, 1396 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
[root@test ~]# iptables -A OUTPUT -p udp --sport 928 -j ACCEPT
[root@test ~]# iptables -A OUTPUT -p udp --sport 111:123 -j ACCEPT   
[root@test ~]# iptables -A OUTPUT -p udp ! --sport 323 -j DROP
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 14 packets, 1028 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 10 packets, 1144 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp spt:928
    0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp spts:111:123
    0     0 DROP       udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp spt:!323

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
[root@test ~]# 

  [!] –destination-port,–dport port[:port]:匹配报文的目标端口或端口范围,当端口连续可以使用:来代替连续的中间端口

[root@test ~]# iptables -nvL 
Chain INPUT (policy ACCEPT 73 packets, 5156 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 54 packets, 6288 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp spt:928
    0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp spts:111:123
    1    76 DROP       udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp spt:!323

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
[root@test ~]# iptables -A INPUT -p udp --dport 928 -j ACCEPT
[root@test ~]# iptables -A INPUT -p udp --dport 111:123 -j ACCEPT   
[root@test ~]# iptables -A INPUT -p udp ! --dport 323  -j DROP
[root@test ~]# iptables -nvL 
Chain INPUT (policy ACCEPT 14 packets, 1028 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp dpt:928
    0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp dpts:111:123
    0     0 DROP       udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp dpt:!323

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 10 packets, 1160 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp spt:928
    0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp spts:111:123
    1    76 DROP       udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp spt:!323

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
[root@test ~]# 

  3、icmp协议的隐式扩展选项

  [!] –icmp-type {type[/code]|typename}

  type/code 的值代表意义

Linux防火墙之iptables基本匹配条件和隐式扩展匹配条件

备注:此图片来源网络

  从上面的表可以看到不同的type,所表达的意思不同,就拿icmp最常用的两个类型,0和8来说,0表示icmp的应答数据包类型,就好比我们去用ping工具去探测远端主机是否存活,可以向远端主机发送icmp协议的8号类型的数据包,对方收到这种类型的数据包,如果正常存活,它会回复一个icmp0号类型的消息,否则它会恢复一个其他类型的数据包(通常情况在对方主机没有设置任何针对icmp协议报文的控制时)

  在iptables里允许我们去ping对方,不允许对方ping我们

[root@test ~]# iptables -F 
[root@test ~]# iptables -A OUTPUT -p icmp --icmp-type 8 -j ACCEPT
[root@test ~]# iptables -A INPUT -p icmp --icmp-type 0 -j ACCEPT
[root@test ~]# iptables -A INPUT -p icmp --icmp-type 8 -j DROP
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 25 packets, 1780 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     icmp --  *      *       0.0.0.0/0            0.0.0.0/0            icmptype 0
    0     0 DROP       icmp --  *      *       0.0.0.0/0            0.0.0.0/0            icmptype 8

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 17 packets, 1580 bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 ACCEPT     icmp --  *      *       0.0.0.0/0            0.0.0.0/0            icmptype 8

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
[root@test ~]# 

  提示:把以上三条规则添加到iptabels中就可以实现我们本机发出去的icmp类型为8 的报文可以正常放行,从对方主机返回icmp类型为0的应答报文可以正常放行,同时明确指定发往本机icmp类型为8的请求报文给予丢弃操作

Linux防火墙之iptables基本匹配条件和隐式扩展匹配条件

    提示:这样是可以拒绝别人用ping工具来探测我们防火墙主机是否存活,当然这样设置后,我们自己想探测都不行了,要想设置自己可以探测,我们可以在规则里添加对应的规则。明确放行特定的icmp数据报文

[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 30 packets, 2084 bytes)
 pkts bytes target     prot opt in     out     source               destination         
   15  1260 ACCEPT     icmp --  *      *       0.0.0.0/0            0.0.0.0/0            icmptype 0
   35  2940 DROP       icmp --  *      *       0.0.0.0/0            0.0.0.0/0            icmptype 8

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 19 packets, 1780 bytes)
 pkts bytes target     prot opt in     out     source               destination         
   36  3024 ACCEPT     icmp --  *      *       0.0.0.0/0            0.0.0.0/0            icmptype 8

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
[root@test ~]# iptables -I INPUT -s 192.168.0.151 -p icmp --icmp-type 8 -j ACCEPT
[root@test ~]# iptables -A OUTPUT -d 192.168.0.151 -p icmp --icmp-type 0 -j ACCEPT        
[root@test ~]# iptables -nvL
Chain INPUT (policy ACCEPT 8 packets, 528 bytes)
 pkts bytes target     prot opt in     out     source               destination         
   12  1008 ACCEPT     icmp --  *      *       192.168.0.151        0.0.0.0/0            icmptype 8
   15  1260 ACCEPT     icmp --  *      *       0.0.0.0/0            0.0.0.0/0            icmptype 0
   46  3864 DROP       icmp --  *      *       0.0.0.0/0            0.0.0.0/0            icmptype 8

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 5 packets, 764 bytes)
 pkts bytes target     prot opt in     out     source               destination         
   36  3024 ACCEPT     icmp --  *      *       0.0.0.0/0            0.0.0.0/0            icmptype 8
    0     0 ACCEPT     icmp --  *      *       0.0.0.0/0            192.168.0.151        icmptype 0

Chain my_chain (0 references)
 pkts bytes target     prot opt in     out     source               destination         
[root@test ~]# 

  提示:如果OUTPUT链的默认处理动作是DROP 需要配置以上两条规则,如果默认规则是ACCEPT 那么在INPUT链上添加一条允许指定源ip的报文允许就可以了

Linux防火墙之iptables基本匹配条件和隐式扩展匹配条件

    提示:可以看到添加了指定的源ip主机允许规则后,用对应的主机ping防火墙主机了。

以上就是tcp、udp、icmp这三种协议的常用隐式扩展选项。

android之Activity的创建与关闭

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