nanog mailing list archives

Re: rfc 1812 third party address on traceroute


From: Josh Reynolds <josh () kyneticwifi com>
Date: Sun, 5 Jun 2016 21:55:06 -0500

I'm assuming you'd like this behavior on EdgeOS changed? I know a guy...
On Jun 5, 2016 8:41 PM, "Randy Bush" <randy () psg com> wrote:

is anyone seeing the dreaded rfc1812 behavior in a citable fashion?  how
common is it?

we verified that the juniper and cisco platforms we tested replied with
the source address being the ingress interface.  this is, imiho, good.

a kind soul actually sent citable tests

At least my MikroTik RB850Gx2, running 'latest stable' (RouterOS
v6.32.2) replies with the outbound interface, not the inbound.

I'd assume this is because by default, icmp_errors_use_inbound_ifaddr in
linux is disabled, and they haven't changed the default.

No idea if that can be tweaked in the weird maze of mikrotik config
options.

and from the same kind engineer

And just to add even more inconsistency, I checked on my Ubiquiti
EdgeMax (a VyOS fork) which does let me check the state of sysctls:

router:/etc/sysctl.d$ cat 30-vyatta-router.conf
<snip>
# Send ICMP responses with primary address of exiting interface
net.ipv4.icmp_errors_use_inbound_ifaddr=1
</snip>

So someone in Vyatta decided to explictly set this to be enabled.

so one win and one loss

randy



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