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Die IPv4, die!

How, how to get rid of IPv4?

Posted on Jan. 9, 2019

Imagine, it is 2019. Easy, ha? Imagine, it is 2019 and you want to turn off IPv4. Like, off off. Really off. Not disabling IPv6, but disabling IPv4.

Two steps back

You might be coming here wondering, why would anybody want to do what we are asking to be done. Well, it is dead simple: We are running data centers (like Data Center Light) with a lot of IPv6 only equipment. There simply is no need for IPv4. So why would we want to have it enabled?

Also, here at ungleich, we defined 2019 as the year to move away from IPv4.

The challenge

Do you like puzzles? Competitions? Challenges? Hacking? Well. If ANY of this is of your interest, here is a real challenge for you:

We offer a 100 CHF (roughly 100 USD) for anyone who can give us a detailed description of how to turn IPv4 completely off in an operating system and allowing it to communicate with IPv6 only. This should obviously include a tiny proof that your operating system is really unable to use IPv4 at all. Just flushing IPv4 addresses and keeping the IPv4 stack loaded, does not count.

The list

How to disable IPv4 in FreeBSD

The following manual for turning off IPv4 in FreeBSD was submitted to us by Alexander Koponen on 2019-01-10 (it has been briefly edited for fitting the blog format).

Here's my instructions on how to build an IPv6-only host, on FreeBSD, without IPv4 stack

Install FreeBSD-12.0 amd64

  • make sure you include the system src package (aka "src")
  • When the installer asks "Would you like to configure IPv4 for this interface?" choose "No"
  • When the installed asks "Would you like to configure IPv6 for this interface?"  choose "Yes"

After system install we can login to machine and ifconfig looks like this:

$ ifconfig
vmx0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500

options=60039b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4,TS
O6,RXCSUM_IPV6,TXCSUM_IPV6>
         ether 00:0c:29:56:b4:50
         inet6 2001:470:de86::abcd prefixlen 64
         inet6 fe80::20c:29ff:fe56:b450%vmx0 prefixlen 64 scopeid 0x1
         media: Ethernet autoselect
         status: active
         nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
         options=680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
         inet6 ::1 prefixlen 128
         inet6 fe80::1%lo0 prefixlen 64 scopeid 0x2
         inet 127.0.0.1 netmask 0xff000000
         groups: lo
         nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>

$ ping -c 2 127.0.0.1
PING 127.0.0.1 (127.0.0.1): 56 data bytes
64 bytes from 127.0.0.1: icmp_seq=0 ttl=64 time=0.044 ms
64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.019 ms

--- 127.0.0.1 ping statistics ---
2 packets transmitted, 2 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 0.019/0.032/0.044/0.012 ms
$ ping -c 2 8.8.8.8
PING 8.8.8.8 (8.8.8.8): 56 data bytes
ping: sendto: No route to host
ping: sendto: No route to host

--- 8.8.8.8 ping statistics ---
2 packets transmitted, 0 packets received, 100.0% packet loss


Which means it doesn't have ipv4 connectivity, but...it still has the ipv4 stack loaded. Let's fix that! Login as root

 

# cd /usr/src/sys/amd64/conf

make a new file called: GENERIC-IPV6ONLY

# vi GENERIC-IPV6ONLY
type this in the file:
   include GENERIC
   ident GENERIC-IPV6ONLY
   makeoptions MKMODULESENV+="WITHOUT_INET_SUPPORT="
   nooptions INET
   nodevice gre

# cd /usr/src
# make buildkernel KERNCONF=GENERIC-IPV6ONLY
(now this takes a long time)
# make installkernel KERNCONF=GENERIC-IPV6ONLY
reboot
login as user
$ uname -a
FreeBSD ipv6-test-0 12.0-RELEASE FreeBSD 12.0-RELEASE GENERIC-IPV6ONLY
amd64
$ ifconfig
vmx0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500

options=60039b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4,TS
O6,RXCSUM_IPV6,TXCSUM_IPV6>
         ether 00:0c:29:56:b4:50
         inet6 2001:470:de86::abcd prefixlen 64
         inet6 fe80::20c:29ff:fe56:b450%vmx0 prefixlen 64 scopeid 0x1
         media: Ethernet autoselect
         status: active
         nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
         options=680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
         inet6 ::1 prefixlen 128
         inet6 fe80::1%lo0 prefixlen 64 scopeid 0x2
         groups: lo
         nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
$ ping -c 2 127.0.0.1
ping: ssend socket: Address family not supported by protocol family
$ ping -c 2 8.8.8.8
ping: ssend socket: Address family not supported by protocol family

Quod erat demonstrandum

The next operating system

So who and what is it going to be? Are you able to figure out how to turn off IPv4 in your operating system?

The fine print

The 100 CHF will be given out as a coupon for using on either of our IPv6 related products:

The 100 CHF will be given out for EACH new detailed report that describes an operating system that we did not yet describe in this article. Derivatives (i.e. Debian <-> Devuan) will only be paid out once. This challenge is valid until 2019-03-03.

Send your solution by email to support at ungleich.ch.

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