Re: Issue with point to point VPNs behind NAT and asymmetric traffic

[Grant Taylor via NANOG <nanog () nanog org>]

On 6/15/19 2:06 PM, William Herrin wrote:
> This is probably enabled on one or both ends:
>
> http://tldp.org/HOWTO/Adv-Routing-HOWTO/lartc.kernel.rpf.html

Do some distros enable this now?

I thought it was disabled by default.

> Disable it.

Or make sure it's using loose (2) filtering.

rp_filter - INTEGER
0 - No source validation.
1 - Strict mode as defined in RFC3704 Strict Reverse Path Each incoming 
packet is tested against the FIB and if the interface is not the best 
reverse path the packet check will fail. By default failed packets are 
discarded.
2 - Loose mode as defined in RFC3704 Loose Reverse Path Each incoming 
packet's source address is also tested against the FIB and if the source 
address is not reachable via any interface the packet check will fail.



--
Grant. . . .
unix || die

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