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Date: Sat, 03 Jan 2015 18:58:06 +0000
From: Paul Thornton <prt@prt.org>
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To: Mike Tancsa <mike@sentex.net>, freebsd-net@freebsd.org
Subject: Re: Issue with forwarding when creates new interface [was USB
 Tethering and forwarding]
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Hi,

On 03/01/2015 18:06, Mike Tancsa wrote:

> do you set forwarding via just /etc/sysctl.conf or in /etc/rc.conf via
> ipv6_gateway_enable and gateway_enable. I seem to recall some discussion
> about there being a difference.  Perhaps devd is calling something that
> then fiddles with the setting ignoring whats in sysctl.conf ?

That seems to be what is happening.

In the earlier post, I was just setting the three sysctls in 
/etc/sysctl.conf - and observed that forwarding went away if an 
interface was added.

Doing it by setting fastforwarding only in sysctl.conf, and setting both 
gateway_enables to yes in rc.conf fixes the problem:

[root@test1 ~]# sysctl -a | grep forwarding
net.inet.ip.forwarding: 1
net.inet.ip.fastforwarding: 1
net.inet6.ip6.forwarding: 1

[root@test1 ~]# ifconfig vlan1 create

[root@test1 ~]# sysctl -a | grep forwarding
net.inet.ip.forwarding: 1
net.inet.ip.fastforwarding: 1
net.inet6.ip6.forwarding: 1

That's quite ... odd, to sat the least.  I can't see anything in 
devd.conf which would relate to a new interface being created, but that 
doesn't mean that there isn't some magic functionality in there.

Paul.