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2018-05-24 01:05:40 +08:00

回复了 mario85 创建的主题 › 宽带症候群 › 电信宽带流量劫持广告复现过程

我似乎抓到劫持包了
似乎所有的劫持包都有一个变量"_atn_obj_"
于是用 iptables 关键字匹配：
iptables -A forwarding_rule -i pppoe-wan -p tcp --sport 80 -m string --string "_atn_obj_" --algo bm -j LOG
同时后台开着 tcpdump
直到内核日志中出现一条：
[54945.458949] IN=pppoe-wan OUT=ct MAC= SRC=119.23.80.130 DST=10.2.1.2 LEN=894 TOS=0x00 PREC=0x00 TTL=56 ID=9997 DF PROTO=TCP SPT=80 DPT=45021 WINDOW=256 RES=0x00 ACK PSH URGP=0

然后我过滤抓包结果：
00:35:20.051969 IP 10.2.1.2.45021 > 119.23.80.130.80: Flags [S], seq 296045250, win 64240, options [mss 1432,sackOK,TS val 3110253 ecr 0,nop,wscale 8], length 0
00:35:20.060124 IP 119.23.80.130.80 > 10.2.1.2.45021: Flags [S.], seq 4085280, ack 296045251, win 14600, options [mss 1444,nop,nop,sackOK,nop,wscale 7], length 0
00:35:20.071531 IP 10.2.1.2.45021 > 119.23.80.130.80: Flags [.], ack 1, win 251, length 0
00:35:20.073405 IP 10.2.1.2.45021 > 119.23.80.130.80: Flags [P.], seq 1:1530, ack 1, win 251, length 1529: HTTP: GET /static/image/mobile/styletouch.css HTTP/1.1
00:35:20.081913 IP 119.23.80.130.80 > 10.2.1.2.45021: Flags [.], ack 1433, win 137, length 0
00:35:20.082025 IP 119.23.80.130.80 > 10.2.1.2.45021: Flags [.], ack 1530, win 137, length 0
00:35:20.094693 IP 119.23.80.130.80 > 10.2.1.2.45021: Flags [P.], seq 1:245, ack 1530, win 137, length 244: HTTP: HTTP/1.1 304 Not Modified
00:35:20.106128 IP 10.2.1.2.45021 > 119.23.80.130.80: Flags [.], ack 245, win 256, length 0
00:35:20.110373 IP 10.2.1.2.45021 > 119.23.80.130.80: Flags [.], seq 1530:2962, ack 245, win 256, length 1432: HTTP: GET /static/assets/js/amazeui.min.js HTTP/1.1
00:35:20.110765 IP 10.2.1.2.45021 > 119.23.80.130.80: Flags [P.], seq 2962:3040, ack 245, win 256, length 78: HTTP
00:35:20.129094 IP 119.23.80.130.80 > 10.2.1.2.45021: Flags [P.], seq 245:1099, ack 2962, win 256, length 854: HTTP: HTTP/1.1 200 OK
00:35:20.129715 IP 119.23.80.130.80 > 10.2.1.2.45021: Flags [.], ack 3040, win 159, length 0
00:35:20.143467 IP 119.23.80.130.80 > 10.2.1.2.45021: Flags [P.], seq 245:490, ack 3040, win 159, length 245: HTTP: HTTP/1.1 304 Not Modified
00:35:20.150041 IP 10.2.1.2.45021 > 119.23.80.130.80: Flags [F.], seq 3040, ack 1099, win 262, length 0
00:35:20.154660 IP 10.2.1.2.45021 > 119.23.80.130.80: Flags [.], ack 1099, win 262, options [nop,nop,sack 1 {245:490}], length 0
00:35:20.361116 IP 10.2.1.2.45021 > 119.23.80.130.80: Flags [F.], seq 3040, ack 1099, win 262, length 0
00:35:20.361483 IP 119.23.80.130.80 > 10.2.1.2.45021: Flags [P.], seq 245:490, ack 3040, win 159, length 245: HTTP: HTTP/1.1 304 Not Modified
00:35:20.394913 IP 10.2.1.2.45021 > 119.23.80.130.80: Flags [.], ack 1099, win 262, options [nop,nop,sack 1 {245:490}], length 0
00:35:20.582203 IP 10.2.1.2.45021 > 119.23.80.130.80: Flags [F.], seq 3040, ack 1099, win 262, length 0
00:35:20.799507 IP 119.23.80.130.80 > 10.2.1.2.45021: Flags [P.], seq 245:490, ack 3040, win 159, length 245: HTTP: HTTP/1.1 304 Not Modified
00:35:20.817570 IP 10.2.1.2.45021 > 119.23.80.130.80: Flags [.], ack 1099, win 262, options [nop,nop,sack 1 {245:490}], length 0
00:35:21.021165 IP 10.2.1.2.45021 > 119.23.80.130.80: Flags [F.], seq 3040, ack 1099, win 262, length 0
00:35:21.675574 IP 119.23.80.130.80 > 10.2.1.2.45021: Flags [P.], seq 245:490, ack 3040, win 159, length 245: HTTP: HTTP/1.1 304 Not Modified
00:35:21.715799 IP 10.2.1.2.45021 > 119.23.80.130.80: Flags [.], ack 1099, win 262, options [nop,nop,sack 1 {245:490}], length 0
00:35:21.904377 IP 10.2.1.2.45021 > 119.23.80.130.80: Flags [F.], seq 3040, ack 1099, win 262, length 0
00:35:23.427507 IP 119.23.80.130.80 > 10.2.1.2.45021: Flags [P.], seq 245:490, ack 3040, win 159, length 245: HTTP: HTTP/1.1 304 Not Modified
00:35:23.454270 IP 10.2.1.2.45021 > 119.23.80.130.80: Flags [.], ack 1099, win 262, options [nop,nop,sack 1 {245:490}], length 0
00:35:26.931735 IP 119.23.80.130.80 > 10.2.1.2.45021: Flags [P.], seq 245:490, ack 3040, win 159, length 245: HTTP: HTTP/1.1 304 Not Modified
00:35:27.118104 IP 10.2.1.2.45021 > 119.23.80.130.80: Flags [R], seq 296048290, win 0, length 0

可以看到
00:35:20.129094 IP 119.23.80.130.80 > 10.2.1.2.45021: Flags [P.], seq 245:1099, ack 2962, win 256, length 854: HTTP: HTTP/1.1 200 OK
这个就是返回的 200 劫持，而真正的服务器返回的是
00:35:20.143467 IP 119.23.80.130.80 > 10.2.1.2.45021: Flags [P.], seq 245:490, ack 3040, win 159, length 245: HTTP: HTTP/1.1 304 Not Modified

根据关键字、TCP FLAGS 和 TTL 匹配包并 DROP 掉
iptables -A forwarding_rule -i pppoe-wan -p tcp --sport 80 -m ttl --ttl-eq 55 --tcp-flags ALL PSH,ACK -m string --string "_atn_obj_" --algo bm -j DROP

存放广告内容的服务器 IP 有 183.59.53.187 183.59.53.188 183.59.53.224 ，po 主的是 183.59.53.197 ，看来可以放心地把整段 IP 屏蔽了

2018-05-23 18:49:23 +08:00

回复了 razios 创建的主题 › 宽带症候群 › 请教局域网内 ftp 传输文件速度为何不快？

路由器 LAN 口百兆？

2018-05-23 14:57:54 +08:00

回复了 c3824363 创建的主题 › 宽带症候群 › 为什么定点搞 TCP 呢，是不是只丢 syn 包开销小

我套了一层 IP-in-IP …

2018-05-17 18:52:36 +08:00

回复了 hzqim 创建的主题 › 问与答 › 选择困难：一个带 WIFI 的千 M 交换机。对，就是普通路由器。

WR1200JS

2018-05-16 22:19:40 +08:00

回复了 remnet 创建的主题 › DNS › 1.1.1.1 号称最快的 DNS

@aceralon SYSU?