This is an extremely unsophisticated program that demonstrates evolutionary DNA. You start by passing it a string:
The Magic Sysrequest Key is Alt (left or right Alt key) and Sysrq (up there under Print Screen, next to F12 on most keyboards). To use it, you need to have it enabled in your kernel (CONFIG_MAGIC_SYSRQ). It usually is; if you have a file called '/proc/sys/kernel/sysrq' you have this. To ENABLE the magic functions, you need a 1 in that file. If it has 0, Alt-SysRq just returns you to the previous console you were using.
On Linux, it's easy enough to add an iptables rule to blacklist a particular ip address. You can even automate the process based on certain criteria that you define. However, you don't necessarily want to leave an ip blacklisted forever, because it may be transient (a legitimate user may have that ip address tomorrow), or the condition that triggered your block may have been an error. The ip address may even have been spoofed, thus denying access to legitimate users.
Sometimes we just have to move on. Your current mail server may just not be meeting your needs, so you've put up something new. But what about old mail? If your servers are identical (Sendmail to Sendmail, etc.) or use the same mailbox storage format, you may be able to just transfer files directly. If not, read on..
There are many tools available to analyze web page statistics. One of the most popular is Analog, but any web search will turn up hundreds or perhaps even thousands more. There are also options like Hitbox which provides statistics gained through code included in your web pages.
Before the wide spread availability of Perl, I would script ftp transfers with .netrc, ksh scripts and other clumsy ways. None of those methods are fun, flexible or easy. On the other hand, Perl's Net::FTP module is all of that.
Recently I had a project that required a number of different programs that will mostly run all the time, but need to be restarted now and then with different parameters. Normally, the first thing I think of for a program that runs constantly is inittab or svc (daemontools). The svc facility is the more flexible of the two, and will be what I'll use in the final design, but in the "thinking" stages I played with using a Perl program launcher and controller. What we have is a config file that specifies programs
Configuration files are a problem for both operating systems and applications. Where do you keep them, how are they structured? Traditionally, Unix systems used text files with wildly varying internal structures, and Windows used either binary data or ".ini" text files (in this sense, "binary" is used for anything that you can't access directly with a simple text editor). More recently, Windows abandoned .ini files in favor of a binary central registry.