System Administration

Evaluating FTP Servers: ProFTPd vs PureFTPd vs vsftpd

/
Usually, I will try to push clients towards using SCP (via a client such as WinSCP), however inevitably there are clients who do not understand this new method of accessing their files securely online, and who for one reason or another insist on using FTP for their online file access. As they say - the customer is always right?

Simple Disk Benchmarking in Linux Using 'dd'

/
A great way to do a real-world disk test on your linux system…

The Easy CIDR Cheatsheet

Even though I've been working with Classless Inter-Domain Routing (henceforth known as CIDR) for years now, I always need a bit up a help remember how many addresses are in each block and how many sub-blocks fit into larger blocks. I have the following printed out for easy reference, and here it is for your geeky enjoyment:
CIDR        Total number    Network             Description:
Notation:   of addresses:   Mask:
--------------------------------------------------------------
/0          4,294,967,296   0.0.0.0             Every Address
/1          2,147,483,648   128.0.0.0           128 /8 nets
/2          1,073,741,824   192.0.0.0           64 /8 nets
/3          536,870,912     224.0.0.0           32 /8 nets
/4          268,435,456     240.0.0.0           16 /8 nets
/5          134,217,728     248.0.0.0           8 /8 nets
/6          67,108,864      252.0.0.0           4 /8 nets
/7          33,554,432      254.0.0.0           2 /8 nets
/8          16,777,214      255.0.0.0           1 /8 net (Class A)
--------------------------------------------------------------
/9          8,388,608       255.128.0.0         128 /16 nets
/10         4,194,304       255.192.0.0         64 /16 nets
/11         2,097,152       255.224.0.0         32 /16 nets
/12         1,048,576       255.240.0.0         16 /16 nets
/13         524,288         255.248.0.0         8 /16 nets
/14         262,144         255.252.0.0         4 /16 nets
/15         131.072         255.254.0.0         2 /16 nets
/16         65,536          255.255.0.0         1 /16 (Class B)
--------------------------------------------------------------
/17         32,768          255.255.128.0       128 /24 nets
/19         16,384          255.255.192.0       64 /24 nets
/19         8,192           255.255.224.0       32 /24 nets
/20         4,096           255.255.240.0       16 /24 nets
/21         2,048           255.255.248.0       8 /24 nets
/22         1,024           255.255.252.0       4 /24 nets
/23         512             255.255.254.0       2 /24 nets
/24         256             255.255.255.0       1 /24 (Class C)
--------------------------------------------------------------
/25         128             255.255.255.128     Half of a /24
/26         64              255.255.255.192     Fourth of a /24
/27         32              255.255.255.224     Eighth of a /24
/28         16              255.255.255.240     1/16th of a /24
/29         8               255.255.255.248     5 Usable addresses
/30         4               255.255.255.252     1 Usable address
/31         2               255.255.255.254     Unusable
/32         1               255.255.255.255     Single host
--------------------------------------------------------------
Reserved Space:
	0.0.0.0/8	
	127.0.0.0/8
	192.0.2.0/24
	10.0.0.0/8
	172.16.0.0/12
	192.168.0.0/16
	169.254.0.0/16

The Dirty Little Secret About SSL Certificates

The dirty little secret about SSL certificates is that:
Anyone can become a certificate authority.
The tools to become a certificate authority, and therefore to publish your own SSL certificates, is included in a wide variety of systems - chances are if you have an Ubuntu or CentOS install you already have the capability of becoming an SSL certificate authority via OpenSSL.

Zalman ZM-VE200 Review - You Need This External Hard Drive Enclosure

/
Fellow tech friends, I have a find for you. If you have a job,…

What a Resilver Looks Like in ZFS (and a Bug and/or Feature)

/
At home I have an (admittedly small) ZFS array set up to experiment with this neat newish raid technology. I think it has been around long enough that it can be used in production, but I'm still getting used to the little bugs/features, and here is one that I just found. After figuring out that I had 2 out of 3 of my 1TB Seagate Barracuda hard drives fail, I had to give the array up for a loss and test out my backup strategy. Fortunately it worked and there was no data loss. After receiving the replacement drives in from RMA, I rebuilt the ZFS array (using raidz again) and went along my merry way. After 6 months or so, I started getting some funky results from my other drive. Thinking it might have some issue as with the others, I removed the drive and ran Seatools on it (by the way, Seatools doesn't offer a 64-bit Windows version - what year is this?). The drive didn't show any signs of failure, so I decided to wipe it and add it back into the array to see what happens. That, of course, is easier said than done.

Disabling The hald-addon-storage Service On CentOS/RedHat

The hald - Hardware Access Layer Daemon - runs several processes…