braindump

apcupsd on RHEL5 / CentOS5

While the current Smart-UPS (aka SMT) range of UPS from APC has much fewer variables exposed in a way that is useful for fancy apcupsd usage (you’ll find apcupsd in EPEL), they are still amply sufficient for home use. Basically, the UPS gives an estimated time left at current load and the remaining battery level. At home these are anyway the only two readings I want to trigger scripts on.

DynDNS updates with TSIG and NetworkManager dispatcher

for paid accounts (DynDNS Pro and Dyn Standard DNS), one can do the updates with TSIG.

This allows us to not use ddclient, thus not having our DynDNS.com password in a config file on disk. Obviously, if the key is leaked, an attacker can still wreak havoc with your DynDNS zone configurations, but at least they will not be able to log onto the web interface of DynDNS under your name.

fixing badly aligned storage

In the olden days, one would have to manually calculate[1] to get a file system (FS), in a logical volume (LV) that was part of a volume group (VG) living on a software RAID, properly aligned. I would get this calculation wrong in about 10% of the cases.

These days, modern Linux distributions like Fedora 14 and RHEL 6 parse hints from the storage.