Date: Thu, 11 May 2023 15:15:45 +1000 From: Ian Smith <smithi@nimnet.asn.au> To: Gary Aitken <freebsd@dreamchaser.org> Cc: TIM KELLERS <trkellers@gmail.com>,questions@freebsd.org Subject: Re: turning off ipv6 on lo0 Message-ID: <33CC3500-3594-423D-BDCB-2321DCF4F1E2@nimnet.asn.au> In-Reply-To: <996b0ce7-0bfe-03e3-0666-6cec58b4ceba@dreamchaser.org> References: <996b0ce7-0bfe-03e3-0666-6cec58b4ceba@dreamchaser.org>
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On 9 May 2023 3:52:44 am AEST, Gary Aitken <freebsd@dreamchaser=2Eorg> wrot=
e:
> Can't seem to figure out how to completely disable ipv6 in
> 12=2E4-RELEASE=2E
> Tried everything I've found in searches, I think=2E
>=20
> rc=2Econf:
>=20
> ip6addrctl_enable=3D"NO"
> ip6addrctl_prefer_ipv4=3D"YES"
> ip6addrctl_prefer_ipv6=3D"NO"
> ipv6_activate_all_interfaces=3D"NO"
> # neither of the 2 lines below have any effect;
> # nor does the absence of them
> # lo0 always has ipv6 configured
> #ipv6_network_interfaces=3D"none"
> #ipv6_network_interfaces=3D""
Yes=2E
> An ifconfig shows no ipv6 on any interfaces except lo0:
>=20
> lo0: flags=3D8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
> options=3D680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
> inet6 ::1 prefixlen 128
> inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3
> inet 127=2E0=2E0=2E1 netmask 0xff000000
> groups: lo
> nd6 options=3D21<PERFORMNUD,AUTO_LINKLOCAL>
>=20
> So how do I get rid of it on lo0?
See /etc/network=2Esubr =2E=2E=2E unless you go drastic and omit ipv6 from=
kernel as Tim suggested, lo0 will have address ::1=2E
> Should I care?
No need to=2E localhost doesn't transact with other than localhost anyway=
AFAIK, and even if tried - as you mentioned running ipfw - rc=2Efirewall i=
nitialisation runs:
setup_loopback() {
############
# Only in rare cases do you want to change these rules
#
${fwcmd} add 100 pass all from any to any via lo0
${fwcmd} add 200 deny all from any to 127=2E0=2E0=2E0/8
${fwcmd} add 300 deny ip from 127=2E0=2E0=2E0/8 to any
if [ $ipv6_available -eq 0 ]; then
${fwcmd} add 400 deny all from any to ::1
${fwcmd} add 500 deny all from ::1 to any
fi
}
where ipv6_available is 0 when "afexists inet6", ie in kernel (/etc/networ=
k=2Esubr)
cheers, Ian
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