Together with some friends I’ve recently tested a temporary wireless network link between Graz and Leutschach, spanning a distance of over 57 kilometers. Using Ubiquiti 5GHz equipment we quickly achieved a stable link with a throughput of about 20 Mbit/s …
I recently bought two Seagate Barracuda 7200 3000GB (SATA 6Gb/s) drives to be used in a Linux software RAID. I knew I had to be careful because of the Advanced Format (AF) layout used by these new drives. Turns out that this wasn’t the only thing that one has to keep in mind when dealing with such drives – GPT BIOS boot partition, anyone?
There are several rather interesting IT conferences every year with presentations to dozens of different topics. Some of these routinely make it into the news while others that are as newsworthy as others don’t make it there. Anyway; having a quick look at the presentation archives usually results in several “wow” style effects and helps to keep up-to-date on current developments in the IT scene.
Here I’d like to provide links to a few of these multimedia archives.
It’s been a while since the last post here, but I just quickly want to mention the D-Link DIR-300. It’s currently the 2nd cheapest WLAN router at the Austrian price comparison site Geizhals – 24 EUR. Of course you can flash it and run alternative firmware such as OpenWRT or DD-WRT.
Just for kicks I got a hardly used one for 10 EUR at eBay. After checking out the D-Link firmware I quickly flashed DD-WRT v24-sp1 on the device. First I tried following the DD-WRT guide for the DIR-300, but it’s a bit misleading, as it tries to catch a sub-second boot prompt to send a break signal. Instead I used a method that’s way easier: Just keep the device’s RESET button pressed while powering it on. It will then halt at the boot prompt – now you can continue following the usual device-flashing guides.
The device seems to work fine, with signal strengths similar to those of my Asus WL500Gp (mind you, that was just a quick in-house distance measurement, not a scientific signal strength study).
Quite a nice device with a very attractive price tag.
Most current Linux distributions support IPv6 out of the box. What most people don’t seem to notice is the fact that most are actively listening for IPv6 router advertisements, meaning that as soon as they see a router advertisement on the same network segment they will happily start to use an IPv6 address out of the advertised space. This doesn’t really look like a security issue – you don’t use IPv6, right – but when you consider that nearly all daemons nowadays are IPv6-capable while most firewalls are only being configured to block IPv4 packets..
To make a long story short: If you are protecting your host with IPv4 firewall rules don’t forget that you might have a security problem if your system reacts to IPv6 router advertisements. It only needs a single compromised box within the same network segment to fully open up all your IPv6-capable daemons, e.g. sshd.
Ever seen the “eth0: no IPv6 routers present” message in your syslog and wondered what it is? 😉
Quick fix: echo 0 > /proc/sys/net/ipv6/conf/all/accept_ra (or better the appropriate /etc/sysctl.conf entry)
There is even a related IPv6 operations internet draft:
Rogue IPv6 Router Advertisement Problem Statement