I've started writing a debian authentication from ldap tutorial. Here is the unfinished text:

It irks me when I am searching for a solution to a problem I have, get a few dozen hits on google, but all I get are people stating the same problem. Here is my attempt at improving the scoring of solutions.

In gdb 6.0 there is a frequently seen problem where the debugger complains about "Error while mapping shared library sections". I was unable to find the real cause of this, but this link stated that an upgrade to gdb 6.1 fixes the problem. There is also a link to a related redhat bugzilla bug entry.

This will show you the IP addresses that have failed to login as well as the number of attempts that failed.

grep ‘Failed password ’ /var/log/auth.log | sed ’s/^.* ([0-9]+.[0-9]+.[0-9]+.[0-9]+) .*$/\1/’ | sort | uniq -c | sort -n | tail -n 10

You can safely ignore a few failed attempts, but I was getting close to 3000 over the last week from one IP. I decided that warranted some action. :)

.

Wasted some time this week converting my server to LDAP directories and renumbering UIDs/GIDs to the “Debian numbering ranges” from the RedHat ranges that I have lived with for 7 years – I have a lot of data to migrate over to the new IDs… data is intact.

LDAP is so ugly after you used SQL, and is a bitch to setup, but after a few hours I managed to get it working with PAM and NSS. I will have to document my steps because I had to read ~10 documents on the web to finally get things working – the Debian packages do not do all the work for you in this case.

I occasionally have footage to take off my MiniDV camera and need to convert it to a format that I can easily burn and archive. I am not much into mastering DVDs, just being able to play the file on my computer is good enough for now.

I've been using kino to do this job before, but that is hard to script. So I decided to play a bit with mencoder. I have no idea what I am doing, so I tried to encode at the highest possible bitrate/quality I could get out of the DivX (mpeg4) encoder.

[ this entry will be updated as I think of more stuff to add ]

ssh & X forwarding

For a while I was having issues with ssh X forwarding to my vserver. Finally found the problem. The problem is actually with X authentication against localhost, and setting localhost to the IP address of the machine in /etc/hosts solved that.

Also someone recommended putting "X11UseLocalhost no" in /etc/ssh/sshd_config.

raw access to block devices

As part of some driver work for a client I looked at some fast logging methods since logging via printk() to syslog sucks.

Here are the hits I got:

• ULOG - it's what netfilter uses for logging packets. It relies on netlink for transport and a ulogd in user space to treat the logs. Apparently ULOG2 is in the works.
• DBUS - patch from Robert Love that adds a fast event notification mechanism to the kernel. It too relies on netlink for transport. It's mostly meant for events like "Your CPU is overheating", not packet logging.
• relayfs - a patch that adds a flexible buffering scheme for logging. Seems like the most flexible of the bunch.