iptables

http://linux.vbird.org/linux_server/0250simple_firewall.php#netfilter

iptables 是利用封包过滤机制, 分析封包的表头资料,根据表头资料定义的规则来决定是否可以进入主机或者被丢弃.

刚才在服务器上练习的时候把自己给屏蔽了,提醒大家拿其他同学的ip做练习,哈哈.

$iptables [-t tables] [-L] [-nv]

-t: 后面接table,  例如nat 或者filter,如果省略此项目,则使用预设的filter

-L:列出目前的table的规则

-n: 不进行IP与HOSTNAME的反查

-v: 列出更多的信息,包括通过该规则的封包总位元数等

tty:[0] jobs:[0] cwd:[/opt/app/]
14:50 [root@a]$ iptables -L -n
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
DROP       all  --  10.103.55.165        0.0.0.0/0           

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination  

15:08 [root@a]$ iptables -h
iptables v1.3.5

Usage: iptables -[AD] chain rule-specification [options]
       iptables -[RI] chain rulenum rule-specification [options]
       iptables -D chain rulenum [options]
       iptables -[LFZ] [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
  --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]        List the rules in a chain or all chains
  --flush   -F [chain]        Delete all rules in  chain or all chains
  --zero    -Z [chain]        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:
  --proto    -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
  --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.

接下来新建一条

15:10 [root@a]$ iptables -A INPUT -s 16.16.136.66 -j DROP

由于写的是自己的ip地址,回车后已不能继续在服务器上继续操作...只能找同学帮忙删了服务器上的配置

查看一下

15:12 [root@a]$ iptables -L -n
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
DROP       all  --  16.16.56.166        0.0.0.0/0           
DROP       all  --  16.16.136.66         0.0.0.0/0           

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination  

删除刚才新建的那条

15:12 [root@a]$ iptables -D INPUT 2