## Slow Down

Anyone who knows me knows I’m quite stubborn. Whenever I set my sights on something I finish it. The last couple of years I’ve been quite busy on GitHub, making at least one commit per day. I’ve had a lot of things I’ve wanted to do and complete, and this commit regimen has kept me on track to do just that. However, nothing comes for free, and although I’ve achieved my goals, I’ve also had to make a lot of sacrifices. [Read More]

## Multicast routing with PIM-SM over GRE

GRE tunnels are useful in many ways. This blog post shows how to set up multicast routing with pimd over a GRE tunnel. To achieve this we will also set up OSPF over GRE with Quagga, because PIM, unlike DVMRP (mrouted), require unicast routing rules to be established.

       .----{ Intranet }----.
/    192.168.1.0/24    \
/                        \
.10 /                          \.20
.--'---. .1  GRE Tunnel  .2 .-----.
|      |====================|      |
|  R1  |   172.16.16.0/30   |  R2  |
|      |                    |      |
'--.---'                    '------'
| .1                        | .1
|    10.0.1.0/24            |    10.0.2.0/24
| .2                        | .2
.--'---.                    .--'---.
|      |                    |      |
|  C1  |                    |  C2  |
|      |                    |      |
'------'                    '------'


In this post we are using the home WiFi network, 192.168.1.0/24, to hook up the GRE tunnel. It is just as easy to extend this to a big corporate Intranet with more routers between R1 and R2. As long as that IT department takes care of the unicast routing between R1 and R2 so that the GRE tunnel can be established.

Most people are completely unaware they exist and end up rolling their own (buggy) implementations. For instance, string manipulation and various forms of linked lists. Which is why I many years ago extracted the frog DNA from Finit to a separate library called libite, or -lite for short. It imports the OpenBSD strlcpy() family of API:s, up-to-date queue.h with the _SAFE` iterators, and more. Some people like libbsd for this, but I’ve found many of the ports incomplete and unsafe and prefer to stay closer to the upstream *BSD versions.