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@willwhui
Last active September 14, 2017 14:21
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客户端Ubuntu的DNS解析防污染(废)
客户端Ubuntu的DNS解析防污染
@lbp0200
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lbp0200 commented Jun 8, 2017

lbp0200 :
先看看ss报什么错误,再看看SwitchyOmega插件设置是否是socks5协议,DNS在这个过程基本不起作用。
DNS只在区分国内外网站的时候有用。
另,测试ss最好用google.com

willwhui:ss看不到报错,我买的别人的服务。switchyOmega插件里面设置了sock5了。
我更新了一下tcpdump的情况。我感觉是在本地就被拒绝了,还没到服务端去,不知道对不对。

另外,DNS的解析影响很大,我在我的路由器上实测确认:默认upd包去做dns解析,哪怕是通过ss-tunnel转发,在运输的过程中也会被人直接截获丢弃,估计是抱着“宁可错杀不可放过”的思想。用pdnsd转换成tcp包做dns解析,通过ss-tunnel转发,目前为止没有问题。参见我的另一个 gist在Openwrt路由器上配置Shadowsocks
补充:我有个朋友告诉我说,如过不是通过路由器整体翻墙,而是通过本地的switchyOmega来连远端ss,Omega会把整个url发给远端,和DNS解析无关。你说的应该是这个意思,是我理解错了。

@willwhui
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willwhui commented Jun 8, 2017

继续排查:


sudo tcpdump -i any host localhost
可见大量如下结果:

17:56:37.657024 IP localhost.1088 > localhost.50016: Flags [.], ack 234, win 350, options [nop,nop,TS val 156575 ecr 156575], length 0
17:56:37.660530 IP localhost.1088 > localhost.50020: Flags [F.], seq 13, ack 229, win 350, options [nop,nop,TS val 156576 ecr 156529], length 0
17:56:37.660703 IP localhost.50020 > localhost.1088: Flags [F.], seq 229, ack 14, win 342, options [nop,nop,TS val 156576 ecr 156576], length 0


sudo tcpdump -i any dst localhost and tcp port 1088
可见大量如下结果:
21:43:33.008249 IP localhost.51686 > localhost.1088: Flags [F.], seq 223, ack 14, win 342, options [nop,nop,TS val 273141 ecr 273141], length 0
21:43:33.008262 IP localhost.1088 > localhost.51686: Flags [.], ack 224, win 350, options [nop,nop,TS val 273141 ecr 273141], length 0
21:43:39.989639 IP localhost.1088 > localhost.51618: Flags [F.], seq 13, ack 229, win 350, options [nop,nop,TS val 274886 ecr 272385], length 0
21:43:39.989817 IP localhost.51618 > localhost.1088: Flags [F.], seq 229, ack 14, win 342, options [nop,nop,TS val 274886 ecr 274886], length 0
21:43:39.989835 IP localhost.1088 > localhost.51618: Flags [.], ack 230, win 350, options [nop,nop,TS val 274886 ecr 274886], length 0

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