linux – iptables阻止DNS

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我在防火墙配置上解锁了端口53,但我的防火墙仍在阻止我的dns查找.

我知道dns查找工作正常,因为如果我将默认的INPUT策略更改为ACCEPT,则名称解析正确完成.

这是iptables脚本

Generated by iptables-save v1.3.5 on Fri Dec  3 12:23:49 2010
*filter
:INPUT DROP [41:3304]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [558:59294]
:RH-Firewall-1-INPUT - [0:0]
-A INPUT -i eth0 -p tcp -m tcp --sport 1024:65535 --dport 22 -j ACCEPT
-A INPUT -s 172.16.0.134 -p tcp -m tcp --sport 1024:65535 --dport 80 -j ACCEPT
-A INPUT -s 172.16.0.134 -p tcp -m tcp --sport 1024:65535 --dport 443 -j ACCEPT
-A INPUT -s 172.16.0.134 -p tcp -m tcp --sport 1024:65535 --dport 20 -j ACCEPT
-A INPUT -s 172.16.0.134 -p tcp -m tcp --sport 1024:65535 --dport 21 -j ACCEPT
-A INPUT -p icmp -m icmp --icmp-type any -j ACCEPT
-A INPUT -d 224.0.0.251 -p udp -m udp --dport 5353 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 53 -j ACCEPT
-A INPUT -p udp -m udp --dport 53 -j ACCEPT
-A OUTPUT -s 172.16.0.4 -j DROP
-A OUTPUT -s 172.16.0.136 -j DROP
-A OUTPUT -s 172.16.0.135 -j DROP
COMMIT
# Completed on Fri Dec  3 12:23:49 2010 <code>

iptables -L收益率

[root@saas-dev-dcpc ~]# iptables -L
 Chain INPUT (policy DROP)
 target     prot opt source               destination
 ACCEPT     tcp  --  anywhere             anywhere            tcp spts:1024:65535 dpt:ssh
 ACCEPT     tcp  --  172.16.0.134         anywhere            tcp spts:1024:65535 dpt:http
 ACCEPT     tcp  --  172.16.0.134         anywhere            tcp spts:1024:65535 dpt:https
 ACCEPT     tcp  --  172.16.0.134         anywhere            tcp spts:1024:65535 dpt:ftp-data
 ACCEPT     tcp  --  172.16.0.134         anywhere            tcp spts:1024:65535 dpt:ftp
 ACCEPT     icmp --  anywhere             anywhere            icmp any
 ACCEPT     udp  --  anywhere             224.0.0.251         udp dpt:mdns
 ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:domain
 ACCEPT     udp  --  anywhere             anywhere            udp dpt:domain

 Chain FORWARD (policy ACCEPT)
 target     prot opt source               destination

 Chain OUTPUT (policy ACCEPT)
 target     prot opt source               destination
 DROP       all  --  172.16.0.4           anywher
 DROP       all  --  172.16.0.136         anywhere
 DROP       all  --  172.16.0.135         anywhere

 Chain RH-Firewall-1-INPUT (0 references)
 target     prot opt source               destination

解决方法

我认为如果你向所有链添加-m state –state RELATED,ESTABLISHED -j ACCEPT规则,这将得到解决.看起来您可能只允许一个方向的DNS流量.

或者,也可以尝试使用–sport 53的规则.

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