Egon Rath – Blog Stuff about the things i am interested in

apt-mirror and misconfigured http proxies

A few weeks ago i sat up a local Ubuntu mirror inside the company i work for - which worked flawlessly until now; For some strange reason the Clients were no longer able to update using the local mirror because of invalid GPG signatures.

After digging around a little bit and lastly asking google for help, it turned out that it was a misconfigured http proxy which delivered some cached files (who were no longer up to date).

Finally i ended up with adding "cache = off" in /etc/wgetrc to instruct the proxy to not use the cache at all.

Refer to http://www.octopuce.fr/apt-mirror-BADSIG-on-security-debian-org-with-solution for more information on this issue.

PDF print of the above site in case it's being removed in the future: apt-mirror_keyproblem

New article: Creating your local Ubuntu/Debian Mirror

Because i've needed one, i wrote done the steps i've used to create one - maybe it's of interest for some of you out there.

Read here: http://www.matrix44.net/cms/notes/gnulinux/create-a-local-ubuntu-mirror

Kerberos Tutorial

Kerberos is not only the Hound of Hades, but also a sophisticated Network authentication and authorization protocol. If you need to set up a Linux network which has centralized user authentication and authorization, you'll probably don't get around it - even if you're using a Windows Active Directory it makes sense to know this piece of technology, as it's also the core of this one.

I am currently planning to authenticate all my home systems using Kerberos and OpenLDAP, i digged around a little bit to learn it - and found a really good introductory tutorial over at cisco.com:

http://www.cisco.com/en/US/tech/tk59/technologies_white_paper09186a00800941b2.shtml

For your convenience the PDF from above is also mirrored here: Kerberos Cisco

Excellent LDAP Tutorial

I am currently playing around with LDAP to authenticate all my Linux systems to a central point. Because i am not the kind of guy who just blindly follows How-To's i was looking for some introduction to LDAP in general (and later on in depth) and OpenLDAP in particular. There are many tutorials out there, but one stood out of all others:

http://www.zytrax.com/books/ldap

This one is awesome! It's written in a clear and funny manner and provides plenty of information - introductory ones, and in depth ones.

Excellent work done here, guys, keep on going!

WebDAV and AutoFS

I am running a webserver with a webdav enabled directory for privately sharing files with my friends and colleagues. For easy access to this share from my Linux boxes, i use the userland davfs filesystem in combination with autofs. This post describes the steps necessary to do so:

1. Install the necessary packages

apt-get install davfs2
apt-get install autofs

2. Configure davfs2 to automatically pass your username/password and accept the self signed server certificate when mounting the remote volume:
2.1. Edit /etc/davfs2/secrets and append a line with the URL, username and password:

https://dav.mydomain.com myusername mypassword

2.2. Copy the Public Key of your WebDAV share (PEM Format) to /etc/davfs2/certs
2.3. Edit /etc/davfs2/davfs2.conf to accept this key when mounting the volume by adding a line with

servercert mycert.crt

2.4. Test it out by manually mounting the filesystem with:

mount -t davfs https://dav.mydomain.com /media/mymountpoint

3. Configure Autofs to automatically mount the filesystem on access
3.1. Append the following line to /etc/auto.master:

/media /etc/auto.webdav

3.2. Create /etc/auto.webdav with the following content:

mymountpoint -fstype=davfs,rw,dir_mode=0777,file_mode=0666 :https://dav.mydomain.com

3.3. Restart autofs:

service autofs restart

If you now access /media/mymountpoint the remote webdav volume should be automatically mounted.