I was installing openswan on my [sbc]{tag/sbc} router box. The sbc doesn’t have much hardware on it, and what it does have did not contribute to the entropy pool.

I have a few boxes around with relatively good entropy (keyboard/mouse input), but there was no way to pass that entropy to the router for RSA key generation. I had to write some code to fix it. Be warned, it’s pretty EVIL…

UPDATE: see below about rng-tools.

Sometimes I have a need to reproduce bugs on other platforms. When that platform uses a heavily patched kernel, it makes it hard to debug. Below are some notes I took while building a RHEL4 kernel with kdb support.

As part of some driver work for a client I looked at some fast logging methods since logging via printk() to syslog sucks.

Here are the hits I got:

• ULOG - it's what netfilter uses for logging packets. It relies on netlink for transport and a ulogd in user space to treat the logs. Apparently ULOG2 is in the works.
• DBUS - patch from Robert Love that adds a fast event notification mechanism to the kernel. It too relies on netlink for transport. It's mostly meant for events like "Your CPU is overheating", not packet logging.
• relayfs - a patch that adds a flexible buffering scheme for logging. Seems like the most flexible of the bunch.