Multiple Interfaces, Not Seeing Requests

[Adam Bishop]

On 7 Feb 2017, at 00:08, Matthew West <matthew.t.west at gmail.com> wrote:
> Since the requests are coming in the same interface that they would be
> going out (same interface/address) why is this required?  I'm going to
> do some troubleshooting and will let you know the results.

I can't be certain it is the cause as you redacted your addresses and didn't mention your gateway/prefix lengths, but the root cause would be that strict mode requires that a packet arrives at the "best" source interface.

e.g:

  eth0 as 10.0.0.2/24
  eth1 as 172.16.0.2/24
  default gw as 10.0.0.1/24

  A packet from 0.0.0.0/0         to eth0 will pass, as it's not from a directly connected subnet and is via the default routed interface
  A packet from 172.16.0.0/12 to eth0 will pass, as it's not from a directly connected subnet and is via the default routed interface
  A packet from 172.16.0.0/24 to eth1 will pass, as it's from the directly connected subnet for eth0
  A packet from 10.0.0.0/24     to eth1 will be rejected, as it's from the directly connected subnet for eth0
  A packet from 172.16.0.0/12 to eth1 will be rejected, as it's not from a directly connected subnet but is not via the default routed interface

When you switch to loose filtering the "best" requirement is dropped; all that matters is that the packets source is reachable via some interface.

Regards,

Adam Bishop

  gpg: E75B 1F92 6407 DFDF 9F1C  BF10 C993 2504 6609 D460

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