Monthly Archive for September, 2008

Can’t connect to X!

Published on September 27, 2008 in Verschiedenes. 0 Comments

Whenever I “su” to work as root and start an X application I get thoese “Can’t connect to X!” errors. This happens because the X-Server is run by the respective user. To avoid this problem you can “forward” the Xauthority from the user to root.

Use this snippet in roots .bashrc:

if [ -n "$DISPLAY" ]; then
  export XAUTHORITY="/home/<username>/.Xauthority";
  export DISPLAY=":0.0";
fi

nfs: No such device

Published on September 26, 2008 in Verschiedenes. 0 Comments

I was trying to mount an NFS share but the mount command failed with “nfs: No such device”. First I was a bit confused, but I soon found the reason: The kernel was compiled without NFS (client) support. D’Oh!

Just recompile the kernel with NFS client support and it will (probably) work.

GnuPG: Change the keyring location

Published on September 17, 2008 in Verschiedenes. 0 Comments

There are several ways to tell GnuPG a custom keyring location.

  • Move .gnupg and set GNUPGHOME to the new location
  • Move .gnupg and use –homedir=<dir> on every invocation of GnuPG
  • Leave .gnupg, only move the keyring and set path to gpg.conf:
no-default-keyring
primary-keyring <dir>/pubring.gpg
secret-keyring <dir>/secring.gpg
trustdb-name <dir>/trustdb.gpg
keyring <dir>/pubring.gpg

GnuPG: Resource requirements

Published on September 17, 2008 in Verschiedenes. 0 Comments

From time to time I let GnuPG refresh the public keys (–refresh-keys) and to my suprise it took over one hour, using one core at 100% and about 6GB of memory. This is bit too much, isn’t it?

MySQL: Replication hints

Published on September 13, 2008 in Verschiedenes. 0 Comments

When you have to handle more queries than your DB is able to handle, if you want to improve reliability or if you don’t want to shut your db down for backups, then you’ll probably look at Replication. For MySQL there is a quite good howto in the official documentation but unfortunately some questions are left open.

First of all you should read the MySQL documentation related to replication. Its well written and contains much important information. If your are setting up exclusive slave nodes, i.e. nodes which only serve as slave and don’t contain data different from the master, you make sure that your slave won’t get corrupted if you set the whole DBMS into read only mode. Just add the line “read_only = 1″ to your my.cnf. Put it below the server_id setting.

Continue reading ‘MySQL: Replication hints’

Secure Remote Storage with FUSE and encfs+sshfs

Published on September 12, 2008 in Verschiedenes. 1 Comment

When you often the computer you work with and you want to have your important files at hand every time you can either carry them around with you on a USB-Stick – perferable encrypted – or you can keep them on a server somewhere. But you’ll probably want to encrypt them there, too. You never know who comes in posession of the data. Beware of the Stasi2.0! One way to achieve secure remote storage is powered by FUSE. With the help of FUSE, encfs and sshfs you can acomplish this task quiete easily. Just get a kernel with FUSE support and install encfs and sshfs. With the help of encfs you can create an encrypted directory (file-level encryption, no blockdevice, no fixed devices size but visible meta-data) and sshfs lets you put this directory on any server on which you have ssh access. Of course not everybody will have an SSH login to some always-on server, but you can easily combine encfs with other remote-storage FUSE drivers. For example GmailFS and there is probably also some WebDAV FUSE driver.

Continue reading ‘Secure Remote Storage with FUSE and encfs+sshfs’

This RRD was created on other architecture

Published on September 10, 2008 in Verschiedenes. 0 Comments

Got trouble moving RRD files (e.g. munin) from one host to the other? Take a look at this: This RRD was created on other architecture

CACert Assurer Challenge

Published on September 2, 2008 in Verschiedenes. 0 Comments

I did manage to pass the CACert Assurer Challenge on the first try, Yeah! :)

So if you want CACert assurance in the area of Frankfurt (Main)/Germany contact me and I’m sure we can arrange a meeting. I provide you with 25 Points for the WoT.

rsync for replication

Published on September 1, 2008 in Linux. 0 Comments

If you want to replicate the contents of a computer to another one over unsecure networks you can use rsync in combination with ssh to acomplish this.

rsync --delete -avze ssh user@hostname.domain.tld:/home/user/ /home/user/backup

This command will replicate the content of the remote machine to the local host. In case you want to use the other directon you can use the following command.

rsync --delete -avze ssh /home/user user@hostname.domain.tld:/home/user/backup

In case you need root privileges for replication take a look at pam_access.

Also take a look at the Ubuntu Wiki.

Debian lenny successor will be called squeeze

Published on September 1, 2008 in Verschiedenes. 1 Comment

Luk Claes announced on the debian-devel-announce list the name of lennys successor, which will be squeeze, a three-eyed space alien.

Release name
~~~~~~~~~~~~
We will continue to use Toy Story character names for lenny’s successor,
which will be called “squeeze” (three-eyed space alien).