我有一个无法解决的问题，我试图访问网络服务器[RPI]，但数据包永远无法到达iptables FILTER链
我会尝试解释一下：
GW1有公共地址，并且从端口8080到端口进行 DNAT，是LAN 的192.168.69.14:80
S1openVPN 服务器，并且VPN 是桥接的，在端口上运行着 Web 服务器，是默认网关，没有公共地址eth0tap0
[RPI]80
GW2[RPI]
GW1 <-----------------> S1 <-----Open VPN tunnel------> [RPI] <--Default route--> GW2
(192.168.69.1) (192.168.69.22) (192.168.69.14 - tap0) (192.168.30.1)
(192.168.30.2 - wlan0)
现在，一切正常，如果我[RPI]从 访问 的网络服务器S1，GW2或者从 执行 ping 操作，GW1
但如果我尝试通过 的GW1公共 IP 端口访问网络服务器8080，数据包会到达[RPI]，但会消失在 中iptables，正如您在此处看到的，规则也iptables打印在下面：
Apr 27 18:13:51 WeatherStorm kernel: [11383.698445] TRACE: raw:PREROUTING:rule:3 IN=tap0 OUT= MAC=82:ed:f9:e6:c2:ea:00:0c:42:f5:XX:XX:XX:XX SRC=37.188.XXX.XXX DST=192.168.69.14 LEN=60 TOS=0x00 PREC=0x00 TTL=50 ID=275 DF PROTO=TCP SPT=33136 DPT=80 SEQ=3502183596 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405360402080A01B215BF0000000001030307)
Apr 27 18:13:51 WeatherStorm kernel: [11383.874415] TRACE: raw:PREROUTING:policy:4 IN=tap0 OUT= MAC=82:ed:f9:e6:c2:ea:00:0c:42:f5:XX:XX:XX:XX SRC=37.188.XXX.XXX DST=192.168.69.14 LEN=60 TOS=0x00 PREC=0x00 TTL=50 ID=275 DF PROTO=TCP SPT=33136 DPT=80 SEQ=3502183596 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405360402080A01B215BF0000000001030307)
Apr 27 18:13:51 WeatherStorm kernel: [11384.051167] TRACE: mangle:PREROUTING:policy:1 IN=tap0 OUT= MAC=82:ed:f9:e6:c2:ea:00:0c:42:f5:XX:XX:XX:XX SRC=37.188.XXX.XXX DST=192.168.69.14 LEN=60 TOS=0x00 PREC=0x00 TTL=50 ID=275 DF PROTO=TCP SPT=33136 DPT=80 SEQ=3502183596 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405360402080A01B215BF0000000001030307)
Apr 27 18:13:51 WeatherStorm kernel: [11384.227423] TRACE: nat:PREROUTING:policy:1 IN=tap0 OUT= MAC=82:ed:f9:e6:c2:ea:00:0c:42:f5:XX:XX:XX:XX SRC=37.188.XXX.XXX DST=192.168.69.14 LEN=60 TOS=0x00 PREC=0x00 TTL=50 ID=275 DF PROTO=TCP SPT=33136 DPT=80 SEQ=3502183596 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405360402080A01B215BF0000000001030307)
Apr 27 18:13:52 WeatherStorm kernel: [11384.459821] TRACE: raw:PREROUTING:rule:3 IN=tap0 OUT= MAC=82:ed:f9:e6:c2:ea:00:0c:42:f5:XX:XX:XX:XX SRC=37.188.XXX.XXX DST=192.168.69.14 LEN=60 TOS=0x00 PREC=0x00 TTL=50 ID=22576 DF PROTO=TCP SPT=33137 DPT=80 SEQ=671043022 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405360402080A01B215FE0000000001030307)
Apr 27 18:13:52 WeatherStorm kernel: [11384.635037] TRACE: raw:PREROUTING:policy:4 IN=tap0 OUT= MAC=82:ed:f9:e6:c2:ea:00:0c:42:f5:XX:XX:XX:XX SRC=37.188.XXX.XXX DST=192.168.69.14 LEN=60 TOS=0x00 PREC=0x00 TTL=50 ID=22576 DF PROTO=TCP SPT=33137 DPT=80 SEQ=671043022 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405360402080A01B215FE0000000001030307)
Apr 27 18:13:52 WeatherStorm kernel: [11384.811610] TRACE: mangle:PREROUTING:policy:1 IN=tap0 OUT= MAC=82:ed:f9:e6:c2:ea:00:0c:42:f5:XX:XX:XX:XX SRC=37.188.XXX.XXX DST=192.168.69.14 LEN=60 TOS=0x00 PREC=0x00 TTL=50 ID=22576 DF PROTO=TCP SPT=33137 DPT=80 SEQ=671043022 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405360402080A01B215FE0000000001030307)
Apr 27 18:13:52 WeatherStorm kernel: [11384.988901] TRACE: nat:PREROUTING:policy:1 IN=tap0 OUT= MAC=82:ed:f9:e6:c2:ea:00:0c:42:f5:XX:XX:XX:XX SRC=37.188.XXX.XXX DST=192.168.69.14 LEN=60 TOS=0x00 PREC=0x00 TTL=50 ID=22576 DF PROTO=TCP SPT=33137 DPT=80 SEQ=671043022 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405360402080A01B215FE0000000001030307)
Apr 27 18:13:54 WeatherStorm kernel: [11386.698855] TRACE: raw:PREROUTING:rule:3 IN=tap0 OUT= MAC=82:ed:f9:e6:c2:ea:00:0c:42:f5:XX:XX:XX:XX SRC=37.188.XXX.XXX DST=192.168.69.14 LEN=60 TOS=0x00 PREC=0x00 TTL=50 ID=276 DF PROTO=TCP SPT=33136 DPT=80 SEQ=3502183596 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405360402080A01B218AD0000000001030307)
Apr 27 18:13:54 WeatherStorm kernel: [11386.874488] TRACE: raw:PREROUTING:policy:4 IN=tap0 OUT= MAC=82:ed:f9:e6:c2:ea:00:0c:42:f5:XX:XX:XX:XX SRC=37.188.XXX.XXX DST=192.168.69.14 LEN=60 TOS=0x00 PREC=0x00 TTL=50 ID=276 DF PROTO=TCP SPT=33136 DPT=80 SEQ=3502183596 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405360402080A01B218AD0000000001030307)
Apr 27 18:13:54 WeatherStorm kernel: [11387.050505] TRACE: mangle:PREROUTING:policy:1 IN=tap0 OUT= MAC=82:ed:f9:e6:c2:ea:00:0c:42:f5:XX:XX:XX:XX SRC=37.188.XXX.XXX DST=192.168.69.14 LEN=60 TOS=0x00 PREC=0x00 TTL=50 ID=276 DF PROTO=TCP SPT=33136 DPT=80 SEQ=3502183596 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405360402080A01B218AD0000000001030307)
Apr 27 18:13:54 WeatherStorm kernel: [11387.228835] TRACE: nat:PREROUTING:policy:1 IN=tap0 OUT= MAC=82:ed:f9:e6:c2:ea:00:0c:42:f5:XX:XX:XX:XX SRC=37.188.XXX.XXX DST=192.168.69.14 LEN=60 TOS=0x00 PREC=0x00 TTL=50 ID=276 DF PROTO=TCP SPT=33136 DPT=80 SEQ=3502183596 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405360402080A01B218AD0000000001030307)
生的：
[root@WeatherStorm tmp]# iptables -L -nv -t raw
Chain PREROUTING (policy ACCEPT 5750 packets, 748K bytes)
pkts bytes target prot opt in out source destination
27 1620 TRACE tcp -- * * 37.188.XXX.XXX 0.0.0.0/0
270 15120 TRACE icmp -- * * 0.0.0.0/0 0.0.0.0/0
51 3958 TRACE tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:80
Chain OUTPUT (policy ACCEPT 4768 packets, 911K bytes)
pkts bytes target prot opt in out source destination
8 448 TRACE icmp -- * * 0.0.0.0/0 0.0.0.0/0
0 0 TRACE tcp -- * * 0.0.0.0/0 37.188.XXX.XXX
曼格尔：
[root@WeatherStorm tmp]# iptables -L -nv -t mangle
Chain PREROUTING (policy ACCEPT 4177 packets, 544K bytes)
pkts bytes target prot opt in out source destination
Chain INPUT (policy ACCEPT 3661 packets, 374K bytes)
pkts bytes target prot opt in out source destination
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 3498 packets, 674K bytes)
pkts bytes target prot opt in out source destination
Chain POSTROUTING (policy ACCEPT 3498 packets, 674K bytes)
pkts bytes target prot opt in out source destination
网络地址转换（NAT）：
[root@WeatherStorm tmp]# iptables -L -nv -t nat
Chain PREROUTING (policy ACCEPT 596 packets, 180K bytes)
pkts bytes target prot opt in out source destination
Chain INPUT (policy ACCEPT 80 packets, 9600 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 59 packets, 4443 bytes)
pkts bytes target prot opt in out source destination
Chain POSTROUTING (policy ACCEPT 59 packets, 4443 bytes)
pkts bytes target prot opt in out source destination
筛选：
[root@WeatherStorm tmp]# iptables -L -nv -t filter
Chain INPUT (policy ACCEPT 23788 packets, 2365K bytes)
pkts bytes target prot opt in out source destination
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 23777 packets, 5142K bytes)
pkts bytes target prot opt in out source destination
知道哪里可能存在问题吗？如果我尝试从GW2它访问，看起来
Apr 27 18:22:02 WeatherStorm kernel: [11873.756818] TRACE: raw:PREROUTING:policy:4 IN=wlan0 OUT= MAC=a0:f3:c1:2f:86:6a:00:1c:bf:8e:XX:XX:XX:XX SRC=192.168.30.1 DST=192.168.30.2 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=34259 DF PROTO=TCP SPT=38739 DPT=80 SEQ=3482087833 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405B40402080A01B3F44A0000000001030307)
Apr 27 18:22:02 WeatherStorm kernel: [11873.850894] TRACE: mangle:PREROUTING:policy:1 IN=wlan0 OUT= MAC=a0:f3:c1:2f:86:6a:00:1c:bf:8e:XX:XX:XX:XX SRC=192.168.30.1 DST=192.168.30.2 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=34259 DF PROTO=TCP SPT=38739 DPT=80 SEQ=3482087833 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405B40402080A01B3F44A0000000001030307)
Apr 27 18:22:02 WeatherStorm kernel: [11873.945646] TRACE: nat:PREROUTING:policy:1 IN=wlan0 OUT= MAC=a0:f3:c1:2f:86:6a:00:1c:bf:8e:XX:XX:XX:XX SRC=192.168.30.1 DST=192.168.30.2 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=34259 DF PROTO=TCP SPT=38739 DPT=80 SEQ=3482087833 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405B40402080A01B3F44A0000000001030307)
Apr 27 18:22:02 WeatherStorm kernel: [11874.039622] TRACE: mangle:INPUT:policy:1 IN=wlan0 OUT= MAC=a0:f3:c1:2f:86:6a:00:1c:bf:8e:XX:XX:XX:XX SRC=192.168.30.1 DST=192.168.30.2 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=34259 DF PROTO=TCP SPT=38739 DPT=80 SEQ=3482087833 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405B40402080A01B3F44A0000000001030307)
Apr 27 18:22:02 WeatherStorm kernel: [11874.133002] TRACE: filter:INPUT:policy:1 IN=wlan0 OUT= MAC=a0:f3:c1:2f:86:6a:00:1c:bf:8e:XX:XX:XX:XX SRC=192.168.30.1 DST=192.168.30.2 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=34259 DF PROTO=TCP SPT=38739 DPT=80 SEQ=3482087833 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405B40402080A01B3F44A0000000001030307)
Apr 27 18:22:02 WeatherStorm kernel: [11874.226404] TRACE: nat:INPUT:policy:1 IN=wlan0 OUT= MAC=a0:f3:c1:2f:86:6a:00:1c:bf:8e:XX:XX:XX:XX SRC=192.168.30.1 DST=192.168.30.2 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=34259 DF PROTO=TCP SPT=38739 DPT=80 SEQ=3482087833 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405B40402080A01B3F44A0000000001030307)
Apr 27 18:22:02 WeatherStorm kernel: [11874.319744] TRACE: raw:PREROUTING:policy:4 IN=wlan0 OUT= MAC=a0:f3:c1:2f:86:6a:00:1c:bf:8e:XX:XX:XX:XX SRC=192.168.30.1 DST=192.168.30.2 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=22857 DF PROTO=TCP SPT=38740 DPT=80 SEQ=3524767168 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405B40402080A01B3F4890000000001030307)
Apr 27 18:22:02 WeatherStorm kernel: [11874.413794] TRACE: mangle:PREROUTING:policy:1 IN=wlan0 OUT= MAC=a0:f3:c1:2f:86:6a:00:1c:bf:8e:XX:XX:XX:XX SRC=192.168.30.1 DST=192.168.30.2 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=22857 DF PROTO=TCP SPT=38740 DPT=80 SEQ=3524767168 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405B40402080A01B3F4890000000001030307)
Apr 27 18:22:02 WeatherStorm kernel: [11874.508565] TRACE: nat:PREROUTING:policy:1 IN=wlan0 OUT= MAC=a0:f3:c1:2f:86:6a:00:1c:bf:8e:XX:XX:XX:XX SRC=192.168.30.1 DST=192.168.30.2 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=22857 DF PROTO=TCP SPT=38740 DPT=80 SEQ=3524767168 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405B40402080A01B3F4890000000001030307)
Apr 27 18:22:02 WeatherStorm kernel: [11874.602511] TRACE: mangle:INPUT:policy:1 IN=wlan0 OUT= MAC=a0:f3:c1:2f:86:6a:00:1c:bf:8e:XX:XX:XX:XX SRC=192.168.30.1 DST=192.168.30.2 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=22857 DF PROTO=TCP SPT=38740 DPT=80 SEQ=3524767168 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405B40402080A01B3F4890000000001030307)
Apr 27 18:22:04 WeatherStorm kernel: [11874.695929] TRACE: filter:INPUT:policy:1 IN=wlan0 OUT= MAC=a0:f3:c1:2f:86:6a:00:1c:bf:8e:XX:XX:XX:XX SRC=192.168.30.1 DST=192.168.30.2 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=22857 DF PROTO=TCP SPT=38740 DPT=80 SEQ=3524767168 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405B40402080A01B3F4890000000001030307)
Apr 27 18:22:04 WeatherStorm kernel: [11874.789331] TRACE: nat:INPUT:policy:1 IN=wlan0 OUT= MAC=a0:f3:c1:2f:86:6a:00:1c:bf:8e:XX:XX:XX:XX SRC=192.168.30.1 DST=192.168.30.2 LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=22857 DF PROTO=TCP SPT=38740 DPT=80 SEQ=3524767168 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT (020405B40402080A01B3F4890000000001030307)
。
解决方案：
iptables按照以下规则 解决S1
iptables -A PREROUTING -t mangle -i br0 -p tcp --dport 80 -d 192.168.69.14 -j MARK --set-mark 1
iptables -A POSTROUTING -t nat --match mark --mark 1 -j SNAT --to-source 192.168.69.1
答案1
您的 路由配置[RPI]不正确 — 如果您希望它可以通过 而从公共 Internet 地址访问GW1，则默认路由必须指向GW1，或者（如果从[RPI]到公共 Internet 地址的传出连接必须通过GW2）您需要在 上配置策略路由[RPI]，以便属于通过 的传入连接的数据包GW1通过 进行路由GW1。
（第三个选项是将数据包发送到GW1，这样它们将来自直接连接的 IP，但在这种情况下，您将无法在处理这些数据包时确定 上的实际客户端地址。对于 HTTP，您可以通过在 上安装反向 HTTP 代理而不是使用 NAT 并在 HTTP 标头中传递真实客户端 IP 来解决此问题。）SNAT192.168.69.1[RPI][RPI]GW1
在你当前的配置中，来自tap0非直接连接主机的数据包可能会被丢弃，因为rp_filter在该接口上启用了ip-sysctl.txt，默认值为rp_filter0，许多发行版在其网络配置中默认启用它）。如果你看看netfilter 数据包流图，rp_filter应用于“路由决策”节点，这与您的观察一致（您看到的最后一个节点是nat:PREROUTING，它就在“路由决策”节点之前）。
请注意，仅禁用rp_filter不会对您有所帮助，因为回复数据包[RPI]将通过 发送GW2，即使它们以某种方式到达另一台主机，它也会拒绝它们，因为这些数据包不会由 进行适当的 NAT 处理GW1。您确实必须确保对通过的 NAT 数据包的回复GW1被发送回GW1 — 没有这个 NAT 将无法正常工作。