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I am following this

Ubuntu Linux - two interfaces, same subnet, different vlan - MAC/ARP issues

# sysctl -w net.ipv4.conf.eth1/102.rp_filter=0
# sysctl -w net.ipv4.conf.eth1/103.rp_filter=0

But this is not working on mac. it gives net: class is not implemented

How can do it in mac

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user3214546
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1 Answers1

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What you are describing is in RFC3704. Apple is a BSD based OS and still has a fair amount different then Linux. In BSD they don't keep this setting in the kernel but in PF. From what I can tell Apple is assuming that everything is in an environment where routing is symmetric.

The particular setting is done using the urpf-failed keyword in filter rules:

block in quick from urpf-failed label uRPF

You are going to want to replace that with:

pass in quick from urpf-failed label uRPF

Apple doesn't make this easy or obvious. Your going to have mess with URPF to make this happen. The easiest way to mess with PF on a Mac is to use Icefloor (http://www.hanynet.com/icefloor/) or Murus (http://www.murusfirewall.com) I am not in a position to test this. But hopefully this points you in the right direction.

Thomas Vincent
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