On 7 Feb 2017, at 00:08, Matthew West <matthew.t.west@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 jisc.ac.uk Jisc is a registered charity (number 1149740) and a company limited by guarantee which is registered in England under Company No. 5747339, VAT No. GB 197 0632 86. Jisc’s registered office is: One Castlepark, Tower Hill, Bristol, BS2 0JA. T 0203 697 5800. Jisc Services Limited is a wholly owned Jisc subsidiary and a company limited by guarantee which is registered in England under company number 2881024, VAT number GB 197 0632 86. The registered office is: One Castle Park, Tower Hill, Bristol BS2 0JA. T 0203 697 5800.