No lazy shortcuts, keep fiber ends clean!

I was working on a major network upgrade project this week with a vendor from a fortune 500 company, most of you would recognize the name of this company if I told you who it was.  The field engineer I was working with was one of their more experienced and highly regarded network engineers.  For the most part he really is pretty sharp, however, at the beginning of the project he started pulling out fiber right and left and tossing it onto the floor with the ends uncovered.  I asked him not to do that and his response was “OK, if you want to be Mr. Clean”.  I explained that we needed to keep the ends of the fiber clean, his response was “don’t worry about it, this stuff is tough”.  What does tough fiber jackets and cladding have to do with understanding that dirty fiber ends can obstruct light and result in optical power loss?  Besides, how long does it really take to cap fiber ends after carefully removing the connectors from patch panels and SFP’s?  It pays to do the job right, no lazy shortcuts allowed!

Facility cabling & fiber installation – What you don’t know can eat you alive

This article is a sequel to the Improperly Polished Fiber Terminations post.

The two cores need to mesh up together flat.

When inserting a patch cord the plastic connector needs to snap into place, if the two ends don’t mesh up flat excessive pressure is required to get the connectors to latch together, this places unusually high strain on the adhesive holding the cladding to the jacket.  If this adhesive cracks or breaks loose then the light’s path is adversely affected and data loss occurs.  When the ends are not completely polished the core also becomes susceptible to cracking & chipping as the  connectors are pushed into the patch panel.

The scary part is that improperly polished ends frequently still pass power-loss & OTDR testing 

Unless the ends are visually inspected with a magnifier no one may even know there is a problem with the fiber terminations until years down the road when the adhesive cracks.   The worst part of all is that the link may not fail completely, it may just become intermittent and/or degrade in overall throughput.

Tips on selecting a data installation vendor

1. Unless you have absolute confidence in a vendor separate out the bids for data installation and data testing.  Have the testing done by a different company than the one that installs the data.
2. Directly contract with the data install vendor, avoid subcontracting in this part of the project.  It is much easier to address data installation issues directly than through multiple levels of contacts and administration.  Position data cabling, data installation and data testing in the construction project in such a way that the I.T. department has control over it.  Do not leave this area solely to the discretion and oversight of a general contractor and/or construction project manager.
3. If you have never used a data vendor before check references from projects of a similar or larger size.

Requirements documents & specifications:  State the obvious

Review the data installation test requirements and never assume - Educate yourself on how to interpret the results of any tests, and understand what constitutes proper, professional installation, otherwise how will you know if the job is done right?

1.  Don’t assume that whoever wrote the test specifications for data installation knows what they are doing.  Educate yourself.
2. Specify the types of certifications you require for the installers and testers.  Ask to see their certifications.
3. Check the calibration sticker dates on test equipment used.  Ask the installers to show you what ranges/settings they are using and record them.  If you aren’t sure of the correct settings, educate yourself.
4. It is a lot easier to challenge poor workmanship if you explicitly list the obvious in the specifications, even if it is an industry standard or in the manufacturer’s installation and/or usage manual.  Provide the installer & tester with a checklist of items you want to see performed or validated.
5. Require testing in both directions, and know how to interpret and validate the test results, particularly if you are dealing with long fiber runs that require OTDR testing.

HDD docking stations

We had a bunch of very large IDE drives that were used with our Idealstor D2D appliance before we upgraded, and we have a bunch of development/test VM’s that I didn’t want chewing up network storage. The solution turned out to be IDE/SATA docking stations, they have worked exceptionally well.  It acts like a monster of a thumb drive, connecting 2.5″ & 3.5″ IDE & SATA drives through USB. The StarTech UNIDOCK2U came pre-packaged with all the necessary cables & accessories for a variety of configurations, setup was quick & painless.

Quick troubleshooting of incoming mail in Eventum

Eventum can be setup to process incoming mail and automatically generate new tickets and/or associate emails with existing tickets.  Eventum is a great piece of software and has been running reliably for us for years.   A few minutes ago the incoming mail wasn’t being downloaded, turned out to be a very simple fix — it was just a lock file and was quickly remedied by doing the following: 

Fix Lock

sudo /usr/bin/php -f <dir>/misc/download_emails.php -- --fix-lock

Download & Process Mail

Could have waited for the cron job, but the following starts the process immediately. 

sudo /usr/bin/php -f <dir>/misc/download_emails.php
sudo /usr/bin/php -f <dir>/eventum/misc/process_mail_queue.php 

Testing, troubleshooting POP3 connectivity & authentication

Method 1: Python

$python
>>> from poplib import *
>>> mail = POP3("hostname-or-IP")
>>> mail.user("user-name")
>>> mail.pass_("password")

Method 2: Netcat

Linux users already have netcat aka nc. For Windows users I recommend snetcat, which supplies a pre-compiled Windows binary.

$nc <hostname-or-IP> pop3
USER <user-name>
PASS <password>

To retrieve messages

RETR 1

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Simple Python-based IMAP4 command-line scripting tool

Where’s Waldo? Better yet, where’s dos2unix in Ubuntu?

There is a Ubuntu package called flip that converts files between UNIX & PC (see the flip man page), but I prefer to stick with the plain old vanilla unix2dos and dos2unix.  unix2dos & dos2unix are pretty much the de facto in the UNIX world for translating line endings.  In Ubuntu unix2dos & dos2unix use the command fromdos alias todos in a package called tofrodos.  Look for unix2dos & dos2unix in a package named tofrodos? fromdos? alias todos? in tofrodos? but just call me dos2unix or unix2dos?  flip‘n twisted?

“Exemplars provide safe models for new designs”

 It was interesting reading “The Design of Design: Essays from a Computer Scientist” by Frederick Brooks after having recently read “The Last Place on Earth” by Roland Huntford.  Captain Robert Falcon Scott tried to design new contraptions and use technology to help him get to the South Pole first.  However, his designs failed time after time.  The reason his designs failed was the same reason Mr. Brook’s highlights in his book; Captain Scott did not thoroughly understand the Exemplars of his day.

“Exemplars provide safe models for new designs, implicit checklists of design task, warnings of potential mistakes, and launching pads for radical new designs. Hence great designers have invested great efforts in studying their precedents… Jefferson carefully studied not only Palladio‘s books, but the buildings around him in Paris… Bach took a six-month unpaid leave from his job and walked 250 miles to study the work and ideas of Buxtehude… Bach proved to be a much greater composer than Buxtehude, but his surpassing excellence came from comprehending and using the techniques of his predecessors,not ignoring them.”

Whether it was hubris or something else, who knows?  But if Captain Scott had intensely studied the exemplars of his day and the tools of previous Antarctic expeditions like Amundsen did, rather than recklessly designing useless contraptions, he would have likely arrived at the South Pole first and made it back to England alive.

So what does this have to do with information technology?  Well, before trying to design new, wild, innovative technology solutions, first study and understand the advantages and disadvantages of existing works.  That is one of the advantages of today’s open source movement, it allows us to thoroughly research exemplars and frequently use what we learn to build solid frameworks for future innovation.

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“USN rollback comes back with a vengeance when Domain Controllers are restored using snapshots.”

In the world of virtualization good admins make snapshots of VM’s before making significant changes, right?  Great idea except you need to be careful, because if you roll back a Microsoft Windows Domain Controller you could put yourself in a world of hurt.  Here is an excellent article from Windows IT Pro magazine written by Greg Shields explaining why you should never rollback a snapshot of a Domain Controller.

Thoughts on “The Design of Design: Essays from a Computer Scientist”, by Frederick Brooks

I recently finished reading “The Design of Design: Essays from a Computer Scientist”,  by Frederick Brooks

Yes, it is the same Frederick Brooks who wrote “The Mythical Man-Month: Essays on Software Engineering” and same Frederick Brooks who was the design architect behind the IBM System/360, reference I.B.M.’s $5,000,000,000 Gamble.

It begins by analyzing various design theories:

• Decision Tree
• Herbert Simon – Decision Making and Problem Solving
• Verein Deutscher Ingenieure – Rational Planning Model
• Winston W. Royce – Waterfall Model
• Pahl & Beitz Method
• Barry Boehm – Spiral Model
• Co-Evolutionary Methods in System Design and Analysis

One interesting observation that Mr. Brooks points out over and over throughout the entire book is that most great inventions have had only one or two chief architects, they were not designed by a committee.

Thinking back through the many projects I have been involved in or witnessed, this observation certainly rings true. Those projects that were compartmentalized with various specialities glued together by a business manager rather than a chief designer/architect had a higher rate of failure. I have observed brilliant ideas ignored because business managers lacking technical expertise weighed the merit of ideas on individual reputations rather than the value of the ideas themselves. A good chief designer/architect can see through this and has the vision and technical expertise to capitalize on new ideas that might otherwise be discarded or dismissed by traditional business/project managers.

I have read some material outside the book where Mr. Brook’s observation is challenged, claims have been made that design teams are often successful on a regular basis. After reading the entire book, I don’t honestly believe Mr. Brooks is suggesting that design teams can’t be successful. He is merely stating that without a chief technical designer/architect free from company procedures, corporate meetings, politics and tampering by business & process managers, the chance of project failure is higher. A chief designer/architect needs to be equally respected and set aside as a separate position from the business/project manager.  One position without the other doesn’t usually work well, one position with more power than the other usually doesn’t work well, nor does it usually work well when both duties are combined into one position. He also states that design by committee creates unnecessary delays & encourages compromises resulting in sacrifices to overall design integrity and project ingenuity. I think these are all very fair observations and there are many more great observations throughout the book, I highly recommend reading it.

How-to setup Ubuntu Server Active Directory integration

Quick & Easy Method

Install Likewise-Open 6.x

Find link for the most current DEB Likewise-Open version 6.x at http://www.likewise.com/community/index.php/download and then download the package (32-bit or 64-bit)from sfx. Example: 

wget http://www.likewise.com/bits/6.0/8234/LikewiseOpen-6.0.0.8234-linux-amd64-deb.sh
sudo ./LikewiseOpen-6.0.0.8234-linux-amd64-deb.sh 

Join the computer to the domain

Note: In the command listed below replace the your-domain-name & your-Administrator-account-name with appropriate information.  You may also use any other privileged account rather than the Administrator account to join the computer to the domain.

sudo domainjoin-cli join your-domain-name your-Administrator-account-name

At the prompt, enter the domain administrator password.   

 Test authentication with domain account

su your-domain-name\\your-Administrator-account-name

Enter the password for the Domain Administrator account at the prompt.    

Configure SSH for Domain Authentication

Edit the SSH config file (replace jed with your favorite editor): 

sudo jed /etc/ssh/sshd_config

Find the Authentication section. You will find a list of names in this field. Add a * (asterisk) to the end.   

Example: 

Allowusers *

Close and save the config file.   

Restart the SSH daemon

sudo /etc/init.d/ssh restart

SSH authentication with domain credentials

ssh your-domain-name\\your-Administrator-account-name@localhost

Add Domain Admins to the Sudoers File

Edit the sudoers file: 

sudo jed /etc/sudoers

Add the following line to the end of the file:  

%your-domain-name\\domain^admins ALL=(ALL) ALL

Save and close the file.  

Usage

To use a domain account to SSH in to the computer, use the following example:  

 login as: your-domain-name\your-AD-account-username

Note: In a Unix shell, a \ (backslash) character is used as an escape key. When referring to a domain account while in a bash shell, use two backslashes. (SSH login prompt only requires one backslash)  

Example:   

su your-domain-name\\Administrator  

Active Directory Groups

You can now use AD accounts in chown & AD groups in chgrp to assign permissions to directories and files just like you would with local Linux users & groups. For example to see your AD groups type the following:

groups

References

• Likewise
• Likewise-Open issues with local user passwords

Credits

Special thanks to Jeremy Dye for providing the information used in this post.