Racker Hacker

If something horrible happened to your Urchin license key or you need to replace it with something else, just run this command to change the key:

cd /usr/local/urchin/util
./uconf-driver action=set_parameter recnum=1 ct_serial=[NEW SERIAL] uconf-driver action=set_parameter recnum=1 ct_license=0

For some reason, this blows up on some Urchin versions. If it doesn’t work, then the command will actually remove your license entirely. Don’t worry! You can log into Urchin’s web interface and put in the new key without a problem.

If you’re used to SHOW PROCESSLIST; or mysqladmin processlist in MySQL, you might be searching for this same functionality in postgresql. Here’s the quick way to get a process list in postgresql:

Switch to the postgres user:
# su - postgres

Get into the postgres shell:
# psql

Then run a quick query:
select * from pg_stat_activity;

NOTE: To actually see the queries being run, you will need logging enabled (it’s disabled by default). I don’t know how to turn it on yet, so this post will be left open until I find out!

One of the nifty things about FreeBSD’s kernel is that it will limit closed port RST responses, which, in layman’s terms, just means that if someone repeatedly hits a port that’s closed, the kernel won’t respond to all of the requests.

You generally get something like this in the system log:

kernel: Limiting closed port RST response from 211 to 200 packets/sec
rkrhkr kernel: Limiting closed port RST response from203 to 200 packets/sec

In certain situations, this functionality might be undesirable. For example, if you’re running an IDS like snort or a vulnerability scanner like nessus, these responses might be helpful. If you want to disable this functionality, just add the following to /etc/sysctl.conf:

net.inet.tcp.blackhole=2
net.inet.udp.blackhole=1