jeltsch's blog

ps2pdf versus pstill and password protection of pdf documents

While reading about ps2pdf (which is just a commandline front-end to ghostscript), I realized that despite its simple appearance, ps2pdf has almost all capabilities of Acrobat 5. ps2pdf14 outputs Acrobat 5-compatible files. According to the documentation strong password protection should be possible, however, I never managed with that.

In theory the following commands should work:

-sOwnerPassword= and -sUserPassword=

In order to set the key length to 128 you have to use
ps2pdf14 -dEncryptionR=3 -dKeylength=128

ssh host keys

When reinstalling an ssh server, one should keep the ssh key files from the old system. Otherwise ssh clients will receive messages of like "IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!". If you didn't keep the files, the clients can of course delete the entries from the host key file (usually /home/user/.ssh/known_hosts). When the user connects after that again to the server, the new, changed host key files are added to the host key file.

The new iPod (3rd generation) and Suse Linux 9

I have bought an iPod. And it appears that the 3rd generation iPod is substantially different from the previous models. E.g. in its file system. In previous models you could convert the HFS+ file system into a FAT32 filesystem. HFS+ is the filesystem used by the new MacOS X OS. It cannot be read by Windows OS (unless you buy commerical third party software such as MacOpener or MacDrive). There are several Linux-interfaces for the iPod, but they all require that the iPod is mounted as a regular mass storage device.

Pages