VirtualBox images to experiment with IPv6

Around me I noticed that a lot of people don’t have hands-on experience with IPv6. The networks they work in do not support IPv6 nor does their ISP provide them with native IPv6 connectivity at home.

On my local systems I often use Virtual Box to set up (IPv6) testing environments. I thought I’d create some Virtual Machine images to get some hands-on experience with IPv6.

The images and README can be found on Github and are aimed to be easy to install and work with.

Requirements

To run the images you need to have Virtual Box installed. You also should be able to use the Linux command line as the Virtual Machines are based on Ubuntu 16.04.

More information can be found in the repository on Github in the README file.

Download

You can download the images here.

How to use

Please take a look at the README on Github. It tells you how to use them.

Happy testing!

Hitch TLS Proxy performance with 15k certificates

While testing with the Hitch TLS proxy in front of Varnish I stumbled upon a slow startup with a large amount of certificates.

In this case we (at PCextreme) want to run Hitch with around 50.000 certificates configured.

The webpage of Hitch says:

Safe for large installations: performant up to 15 000 listening sockets and 500 000 certificates.

10 minutes

I started testing on my local desktop with 15.000 certificates. My desktop is a Intel NUC with Ubuntu 14.04.

wido@wido-desktop:~/repos/hitch/src$ time sudo ./hitch -n 4 -u nobody -g nogroup --config=/opt/hitch/hitch.conf

real    9m40.088s
user    9m38.482s
sys 0m0.829s
wido@wido-desktop:~/repos/hitch/src$

A 10 minute startup time for Hitch is rather long. We started searching for the root-cause.

OpenSSL

After some searching we discovered the OpenSSL version in Ubuntu 14.04 was the problem. Testing with Ubuntu 15.10 showed us different results.

root@VM-9d8e8cfd-e30f-4c40-8c4e-2e098b0f11a5:~# time hitch --daemon --pidfile=/run/hitch.pid --user hitch --group hitch --config=/etc/hitch/hitch.conf

real    0m18.673s
user    0m6.780s
sys    0m2.000s

18 seconds is a lot better than 10 minutes!

Ubuntu 14.04 comes with OpenSSL 1.0.1f and Ubuntu 15.10 with 1.0.2d and that is where the difference seems to be.

100.000 certificates

After this we started testing with 100k certificates. It took 48 seconds to start with that amount of certificates configured.

For production we will use Ubuntu 16.04 which has similar results as Ubuntu 15.10.

So if you find Hitch slow when starting, check your OpenSSL version.

AnyIP: Bind a whole subnet to your Linux machine

IPv6 Prefix Delegation

In my previous post I wrote how you can use Docker with IPv6 and Prefix Delegation.

A IPv6 subnet routed to a Linux machine can be used with other things than Docker. That’s where the AnyIP feature of the kernel comes in.

Linux Kernel AnyIP

The AnyIP feature of the Linux kernel allows you to bind a complete IPv4 or IPv6 subnet to your system.

Instead of adding all addresses manually to the kernel you can tell it to bind a complete subnet.

Configuring

IPv4

ip -4 route add local 192.168.0.0/24 dev lo

In this case the Linux kernel will now respond to ARP requests for any IPv4 address in the 192.168.0.0/24 subnet.

IPv6

ip -6 route add local 2001:db8:100::/64 dev lo

In this case the kernel will respond for Neigh Sollicitations on any IPv6 address in the 2001:db8:100::/64 subnet.

Example usage

Let’s assume that you have the IPv6 prefix 2001:db8:100::/60 routed to your Linux machine through IPv6 prefix delegation.

From that /60 subnet we take the first /64 subnet and attach it to lo.

ip -6 route add local 2001:db8:100::/64 dev lo

You can now ping any of the addresses in that subnet:

2001:db8:100::1
2001:db8:100::100
2001:db8:100::200
2001:db8:100::dead:b33f

If you would start a webserver which listens on port 80 you can use any of the IPv6 addresses in that subnet and the webserver will respond to it.

Use cases

It could be that you want to to mass-shared hosting on a system where you want to assign each hostname/domainname it’s own IPv6 address. Instead of attaching single IPs to a interface you can simply attach a complete subnet and point traffic to any of the IPs in that subnet.

Demo

On a virtual machine on PCextreme’s Aurora Compute I deployed a Instance with Prefix Delegation enabled.

After running ‘dhclient’ I got the subnet 2a00:f10:500:40::/60 assigned to my Instance.

It was then just one line to attach a /64 subnet:

ip -6 route add local 2a00:f10:500:40::/64 dev lo

Random address generator

I wrote a small piece of Python code to generate a random IPv6 address:

#!/usr/bin/env python3
"""
Generate a random IPv6 address for a specified subnet
"""

from random import seed, getrandbits
from ipaddress import IPv6Network, IPv6Address

subnet = '2a00:f10:500:40::/64'

seed()
network = IPv6Network(subnet)
address = IPv6Address(network.network_address + getrandbits(network.max_prefixlen - network.prefixlen))

print(address)

Using a small loop in Bash I could now ping random addresses in that subnet:

while [ true ]; do ping6 -c 2 `./random-ipv6.py`; done

Some example output:

--- 2a00:f10:500:40:d142:1092:ea84:74b4 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1000ms
rtt min/avg/max/mdev = 10.252/11.680/13.108/1.428 ms
PING 2a00:f10:500:40:4e50:f264:6ea9:d184(2a00:f10:500:40:4e50:f264:6ea9:d184) 56 data bytes
64 bytes from 2a00:f10:500:40:4e50:f264:6ea9:d184: icmp_seq=1 ttl=56 time=10.0 ms
64 bytes from 2a00:f10:500:40:4e50:f264:6ea9:d184: icmp_seq=2 ttl=56 time=10.0 ms

--- 2a00:f10:500:40:4e50:f264:6ea9:d184 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1000ms
rtt min/avg/max/mdev = 10.085/10.087/10.089/0.002 ms
PING 2a00:f10:500:40:d831:1f89:b06d:fe12(2a00:f10:500:40:d831:1f89:b06d:fe12) 56 data bytes
64 bytes from 2a00:f10:500:40:d831:1f89:b06d:fe12: icmp_seq=1 ttl=56 time=9.77 ms
64 bytes from 2a00:f10:500:40:d831:1f89:b06d:fe12: icmp_seq=2 ttl=56 time=10.1 ms

--- 2a00:f10:500:40:d831:1f89:b06d:fe12 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1005ms
rtt min/avg/max/mdev = 9.777/9.958/10.140/0.207 ms
PING 2a00:f10:500:40:2c45:26ee:5b93:fa2(2a00:f10:500:40:2c45:26ee:5b93:fa2) 56 data bytes
64 bytes from 2a00:f10:500:40:2c45:26ee:5b93:fa2: icmp_seq=1 ttl=56 time=10.2 ms
64 bytes from 2a00:f10:500:40:2c45:26ee:5b93:fa2: icmp_seq=2 ttl=56 time=10.0 ms