Simple Mail Transfer Protocol

Authenticated Test Message

this is a test message

Sizing your Internet/WAN Edge

The internet is getting faster and faster. I now have Gigabit Fiber delivered to within a foot of my home router. The carrier then is kind enough to provide a smart jack that converts the fiber delivery to a Gigabit Copper handoff.

More bandwidth is better right? Well kinda… Unfortunately, I hadn’t planned on one thing I am now much more vulnerable to denial of service attacks. Why is this an issue? Whats an engineer to do? Read on.. Continue reading

Cisco Auto-Provisioning Lab

So I have had need to quickly build a provisioning server for a lab to auto provision devices as they come online. This is the basic steps to accommodate this. Note there are far more complex and secure methods to utilizing something similar in production. Feel free to use this as a learning tool, but understand in a production environment, this is not recommended as critical pieces of information would be sent in clear text.

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fully dynamic fluxbox menu

I needed the ability to generate a menu dynamically in Fluxbox for various things that change on a regular basis.

Unfortunately, there doesn’t appear to be a facility built into fluxbox to allow for this. So I spent some time and built a partially dynamic menu that updates with the click of an ‘update’ menu item at the root menu.

I was trying to come up with a good way for the menu to update on the fly. Since fluxbox simply reads a menu file (when you use the [include] function) I needed a file that when read, it returns a dynamic response and begins the process again. It’s not completely in time, but it at least refreshes on the fly. So what is a file that provides these properties?

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Execution Performance, Linguistics, Totalitarian Elitism, and of course Python: Language as a construct of action

I’m an elitist in the worst way sometimes, so this is probably the pot calling the kettle black. But I simply want to pose a question, that no doubt will spark great debate among a very divided culture:

Why does the coding style we use to imply organization of the characters in the document representing code need to be so explicitly tied to the keywords, syntax, semantics, operators, closure, and the most important part… the resulting libraries that make up the development environment we seek to develop within?

It’s always the same argument Braces and Semi’s versus Linguistic command flow.

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Debian 7 Wheezy Installation in FreeBSD 10 Jail

I decided to collapse the multiple systems I have running various flavours of Linux and BSD into a  single system. For a long time I had been using Windows Small Business Server. Well I don’t really want to spend the money to upgrade to 2016 and since it appears Microsoft has abandoned its purist Unix roots by trading the tight and tidy SFU (Interix) for the wildly fat Ubuntu and a Linux ABI. In the advent of this change, I figured I would flip back to FreeBSD, which in my not-so-humble opinion is still the closest thing to Unix you can get. In fact, it actually derives its original sources from none other than Research UNIX, and while it’s wildly more advanced, the distribution holds it’s origin close to it’s heart.

Either way, the task: Support the ever growing number of ‘Appliance’ installs on top of FreeBSD. In this first iteration I have found several guides and worked through getting Debian 7 functional in a FreeBSD 10-STABLE Jail. No guarantees on stability, but I’ll update this if I come across any oddities. This task was performed on FreeBSD 10.3.

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Negative Overflow of 4-byte AS in Solarwinds Orion Output

4-byte (32-bit) BGP Neighbor Information with AsDotNotation

A problem currently exists within Solarwinds where 4-byte (32-bit) ASNs overflow into a negative number when utilizing a portion of the private scoped ASN space specifically, the ranges 2,147,483,648 (32768.0) through 4,294,967,296 (65535.65535) overflow into -2,147,483,648 through -1 respectively.

To show the correct data, we created a custom table utilizing the following WSQL to generate the correct information. See past the snippet for an explanation as to how and why this works.

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Linux/UNIX Pipes File Descriptors, and Process Substitution

Linux/UNIX Pipes File Descriptors, and Process Substitution

  • POSIX Shell – A logical container providing an environment and a set of commands to interact with a UNIX and/or UNIX-like system.
    Examples include: sh(Bourne shell), bash, ash, csh, etc.
  • Pipe – a unidirectional connection between two processes utilized for inter-process communications.
  • File Descriptor (fd) – A dynamically created, locally significant and non-persistent file representation of a FIFO buffer which can be connected to a pipe, or by default to the parent process’ standard input, output, and error buffers. As an example, a (virtual) terminal’s input device (keyboard, mouse, etc.) and output device (display).
  • Process substitution – Allows the POSIX shell user the ability create scripted constructs that mimic functional and/or imperative programming syntax in-line.

Every interactive process on startup within a POSIX shell is attached dynamically to three pipes local to its memory space. Standard Input(0), Standard Output(1), and Standard Error(2). If the POSIX system supports file descriptors they are then created and attached to the pipes at ‘/dev/fd/’.

Name Abbrev. File Symbols
standard input stdin /dev/fd/0 < or <<
standard output stdout /dev/fd/1 1> or 1>>
standard error stderr /dev/fd/2 2> or 2>>

POSIX Shell Plumbing

The POSIX (Bourne) shell and its derivatives provides the ability to utilize various symbols to plumb processes together by their file descriptors.

Symbol Name _Symbol_Syntax_ ________Function________
pipe { block } | { block } attach stdout of left script block
to  stdin of right script block
cmd && { block } if cmd exits with success (0)
then execute block
cmd || { block } if cmd exits with error (not 0)
then execute block
{ block } #>file attach /dev/fd/#
of left script block to file
and overwrite with bytestream
{ block } #>&? attach /dev/fd/#
of left script block to /dev/fd/?
and overwrite with bytestream
append { block } #>>file attach /dev/fd/#
of left script block to file
and append bytestream
#>&- close /dev/fd/#
(no # specified defaults to stdout)
{ block } <file attach stdin of left script block
to file and read bytestream
{ block } <&? attach stdin of left script block
to /dev/fd/? and read bytstream
{ block } <<word attach stdin of left script block
to stdin of proc
and read until word
close stdin <&- close stdin

Process Substitution

The POSIX shell also provides the ability to perform inline substitution utilizing two methods:

Symbol_Syntax ________Function________
sub-shell exec ( block ) execute process proc without environment persistance
sub-block exec { block; } execute proc resulting inline at location within script with evnironment persistance

…for examples see below

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