Long-term Memory

Everyone that has used the Cisco IOS command line knows this problem. When you mistype a command, the router tries to resolve the “hostname” and you have to wait for 24 very long seconds:

Router#conft
Translating "conft"...domain server (255.255.255.255)
 (255.255.255.255)
Translating "conft"...domain server (255.255.255.255)
% Unknown command or computer name, or unable to find computer address
Router#

Until recently I used the “no ip domain-lookup” configuration entry to counter this. This disables DNS-lookups altogether, which might not always be what you want. I recently found the proper solution to fix this:

Continue reading ‘Avoiding the typo penalty in Cisco IOS’ »

When I’m debugging serial communications, it’s very useful to run the standard application inside a VM. This allows me to connect the virtual RS232 port to the physical one with socat, which provides me with a detailed log of every byte.

The VMware products under Windows and linux have the option to connect their serial port to a “named pipe“, although it’s more a socket, since they allow bidirectional communication. Strangely enough, VMware Fusion, the Mac product, does not have this option.

Continue reading ‘Connecting a serial port from VMware Fusion to a unix socket’ »

At my parents place, we installed photovoltaic cells. The produced electricity is converted to AC power and is coupled with the normal grid: if we produce too little, the grid provides the remaining power; overproduction is given to the grid.

The inverter (the device that converts DC into AC) is a SolarMax C-series. It has a 2-line LCD display that gives out some basic information: current, voltage, power; produced energy today, this month, this year, … This is very useful information, but is a bit hard to access. The instruction manual reveals that there is a computer interface available to read out its data. Naturally, I wanted to explore this!

Continue reading ‘SolarMax MaxTalk protocol reverse engineered’ »

I was bored of constantly looking for updates on a website. A little googling turned up this nice site. It turns (a part of) a webpage into an RSS feed. Here are the ones I created:

• Cisco Catalyst 2960 Series Switches – Release Notes
• Cisco Catalyst 3560 Series Switches – Release Notes
• Cisco Catalyst 3560-E Series Switches – Release Notes
• Cisco Catalyst 3750 Series Switches – Release Notes
• Cisco Catalyst 3750-E Series Switches – Release Notes

When I was updating my GPG/OpenPGP key, I did some research on the internals of the keys. There appear to be very nice tools to explore the internals of a key. You can also manipulate this key in different aspects: use multiple passwords on a single key, remove part of a secret key for enhanced security; you can even move subkeys between master-keys.

Continue reading ‘The internals of an OpenPGP key’ »

When troubleshooting a network performance problem today, I discovered some strange behavior when using an internet connection over a cellular network (GSM in my case):

When the line was idle for half a minute or so, the connection seems to hang a few seconds before working again. I verified this with our mobile provider Proximus and got the following interesting response: (liberally translated by me)
Continue reading ‘Setup delay on wireless data networks’ »

Up until now, I logged into my blog using the standard username/password. Since my blog is hosted as a vhost, setting up SSL (https) is a pain: You either need a dedicated IP:port per ssl-vhost, or need to work with certificates that list multiple domains (Update 2009-04-18: SNI). Running SSL on a non-standard port works pretty well, but most firewalls don’t like that. Conclusion: the only widely available way to log into my blog is over plain http. Needless to say, I don’t like my password going in plaintext over the Internet.

Continue reading ‘OpenID’ »

If I log in to my Ubuntu box over SSH from my MacOSX terminal, then start screen, my backspace-key doesn’t work anymore. Pressing it deletes the first character on the right of the cursor, instead of the one on the left. This only happens inside screen, not on the regular bash-shell.

I found different workarounds:

• A forum post telling to change the terminal preferences to send backspase as CTRL-H (ASCII 0x08) instead of the normal ASCII 0x7f.
• A blogpost telling to lie about the terminal you’re using: “TERM=screen screen”
• Another blog telling to do remapping inside screen with bindkey-commands

None of the above worked without side-effects: CTRL-H is not understood by MacOSX terminal applications; bindkey-commands are applied even if I SSH from my linux box.

The solution I like best is to change the terminal from the standard “xterm-color” to “rxvt”. After this change, everything worked like a charm.

My previous system was a Linux-box. I made some adjustments to my keyboard in order to make it “better”. Since I use Vim a lot (apologies to Emacs-fans), the escape-key is doing overtime. On a normal keyboard however, the escape-key is located at the top left. Other keys are very near the main keyboard, but are hardly used. I almost never use the CapsLock key at all. So I switched both keys around, giving the CapsLock key the escape-function and the other way around.

Under Linux, you can remap keys using xmodmap. It seems that Windows has a similar feature, although much less documented. Here is a short summary of this article.

Continue reading ‘Remap keys under Windows’ »

IPv6 is, big surprise, the new version of IP. The current internet runs on IPv4, which has some drawbacks. Practically both versions are the same: they allow connections from one host to another host. Technically however, there are some major differences, most notably the enlarged address space. For the moment, most hosts will run a dual-stack configuration.

I decided that it was time to implement IPv6 on my home network and get a IPv6 connection to the IPv6-Internet.

Continue reading ‘IPv6 in the home network’ »