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On Fri, Dec 25, 2015 at 9:00 PM, Adam Carter <adamcarter3@×××××.com> wrote: |
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>> grandstream.yagibdah.de (192.168.3.80) auf 00:0b:82:16:ed:9e [ether] auf |
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>> enp2s0 |
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>> grandstream.yagibdah.de (192.168.3.80) auf 00:0b:82:16:ed:9e [ether] auf |
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>> enp1s0 |
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>> spa.yagibdah.de (192.168.3.81) auf 88:75:56:07:44:c8 [ether] auf enp2s0 |
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>> spa.yagibdah.de (192.168.3.81) auf 88:75:56:07:44:c8 [ether] auf enp1s0 |
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>> |
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>> |
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>> enp2s0 is an interface dedicated to a PPPoE connection, and enp1s0 |
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>> connects to the LAN. |
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>> |
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>> IIUC, this is bound to cause problems. |
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>> |
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>> How is it possible for the wrong entries to be created, and what can I |
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>> do to prevent them? |
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>> |
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> |
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> arp mappings are untrusted so your machine will accept anything is sees on |
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> the network. That's what makes MITM so easy on a connected subnet. What |
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> makes you think they are wrong? Also, the output of ifconfig would be |
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> helpful. |
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|
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I suspect those interfaces are getting bridged or something, but I'm |
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not an expert on such things. |
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|
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If a given IP has a MAC on more than one interface, the interface the |
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packets go out to is still controlled by the routing rules. If the |
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routing rule says that 1.1.1.1 is on eth0 it doesn't matter that eth0 |
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doesn't have an ARP entry and eth1 does - I believe it will just be |
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undelivered or sent to the gateway for eth0 if it isn't on a local |
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subnet for that interface. If you have some kind of routing loop it |
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could actually make its way back to the interface on eth1. ARP |
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doesn't come into play until the kernel goes to send something on an |
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interface and determines it is on a subnet for that interface. Again, |
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I'm not an expert in this and there could be some nuance to the rules |
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that I'm missing. |
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|
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-- |
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Rich |
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