The Lone Sysadmin

“If builders built houses the way programmers built programs, the first woodpecker to come along would destroy civilization.”

I was reading Raj Dash’s post “41 Reasons Why Your Blog Probably Sucks.” Reason number 30 sticks out to me: Unfriendly URLs.

He’s talking about blogs, specifically, but this is a battle I fight every day with web applications.

When we build new services and deploy new applications we have a choice. Do we make the users remember some awful URL, or do we use DNS and web redirects & aliases to simplify things?

Here’s an example from my life. Someone in my organization thinks it’s okay to make people remember this URL in order to do their time reporting:

https://barney.company.com:9001/OA_HTML/US/ICXINDEX.htm

If I’m on a machine where I don’t have that URL bookmarked I won’t be able to find it. I have to ask someone, look in documentation, or call a Help Desk, all of which makes me feel like an idiot. Like most others, I don’t like feeling like an idiot. Why couldn’t they have registered something easy to remember, like:

https://timesheet.company.com/

as a virtual host and redirected me to the right place?

This also goes for http:// vs. https://, too. If you want your service to use SSL then make it friendly for those people who just type time.company.com in their browser (which will always assume http://). Redirect them to the SSL side, rather than going nowhere or giving them an error.

I install a tftp server about once every three years. As such I never remember what needs to happen, and this time a Google search didn’t have a nice answer for me. So, as my latest contribution to the world of HOWTOs, I present the non-idiot’s concise guide to installing and configuring a tftp server.

As always if you have suggestions or corrections just add them as comments, and I’ll update the text here.

This will give you the default /tftpboot directory. I assume that if you need a filesystem there you can handle adding one there on your own. :-) If you want to change the filesystem you can do that in /etc/xinetd.d/tftp, in the server_args field. Don’t forget to reload xinetd after you change it.

1. Install the tftp server software and enable it:

/usr/bin/up2date tftp-server
/sbin/chkconfig tftp on

3. Because it runs via xinetd reload that to pick up the configuration file change:

/sbin/service xinetd reload

4. Edit /etc/sysconfig/iptables-config and edit the IPTABLES_MODULES line to read:

IPTABLES_MODULES="ip_conntrack_tftp"

If you already have something in that line just add the new module with a space as a delimiter, like:

IPTABLES_MODULES="ip_conntrack_ftp ip_conntrack_tftp"

5. Add firewall rules to /etc/sysconfig/iptables. You probably only need UDP, though I always add the TCP rules, too (they’re both listed in /etc/services for port 69):

-A RH-Firewall-1-INPUT -s 10.1.0.0/16 -m tcp -p tcp --dport 69 -j ACCEPT
-A RH-Firewall-1-INPUT -s 10.1.0.0/16 -m udp -p udp --dport 69 -j ACCEPT

(two lines here if it’s wrapping)

6. Restart iptables to pick up the changes from steps 4 and 5:

/sbin/service iptables restart

7. Add the proper lines to /etc/hosts.allow:

in.tftpd: 10.1.

8. Put something in /tftpboot to retrieve with a client, for testing.

9. Use a client from an allowed IP range to test:

$ tftp my.tftp.server.com
tftp> get filename.bin


9. If you get an error check /var/log/secure and /var/log/messages on the server, and start eliminating potential problems one at a time (disable iptables, put ALL in hosts.allow, etc.) until you find the problem.

Have fun!

Term that causes mental shutdowns: living document

Rationale: Some glossaries state that “in a living document a topic is covered more completely over time” but I don’t see how that doesn’t apply to all documents. Aren’t all documents editable, with varying degrees of work required to edit them? It seems that the term “living document” is mainly used by people who want others to think print is dead. It just takes more time for the revisions to be published for printed material.

When a document updates itself it can be dubbed “living” but until then it’s a mechanical turk, with me as the part that’s alive.

Watch words: organic, ecosystems.

What won’t make my head explode: refer to it as “updating the document.”

• Seth’s Blog: Permeability
• jwz - your money is full of lies!
• Interpreting Apple - Vox
  It’s interesting that within most organizations the world-changing things start out as a single suggestion from a single individual, often in a team far away from the actual product team. Apple appears no different.
• SPACE.com — Lunar Lander Challenge Ends in Fire, Disappoinment
  Bad news for John Carmack’s Armadillo Aerospace.
• Staph infection here to stay
  It’s the overuse of antibacterial cleaning products and antibiotics that created this problem. Oh, and while we’re at it I’d like to see the Intelligent Design folks explain how this isn’t evolution. Was the bacteria just waiting until now to strike back?
• HouseFront | Your Real Estate Search and Valuation Tool
  Cool - text an address to ‘HOUSE’ on your phone (46873) and it’ll give you stats and a valuation.

• Joyeur: NetApp versus Sun, Sun versus NetApp, and Both versus Common Sense
  Excellent points. I suspect both companies will lose customers and marketshare when this is all said and done.
• 5 Reasons Why You Should Simplify What You Say, and How to Do It
  “Going on and on about something may be a way to show off your cleverness. Cleverness is overrated. It’s mostly a good way to feed your own ego.”
• Pug Monitor Cleaner (Shockwave)
  ROFL.
• ImaginEERIEing : Magic Mirror

• VMware Tips
• Void After Midnight » G.M. Weinberg’s Secrets of Consulting
• A field guide to iPods - The Unofficial Apple Weblog (TUAW)
• Getty Images - News Blog » Blog Archive » Documenting a “Planet in Peril”
• 24 Hours of Leopard: AutoFS - The Unofficial Apple Weblog (TUAW)
  Hot damn, probably the one feature I want out of Mac OS the most — not dying if I forget to unmount a volume before I put my girlfriend’s laptop to sleep.
• Mac OS X 10.5: Time Machine doesn’t back up to AirPort Disks
  L-A-M-E.
• Evidence Based Scheduling - Joel on Software
  Interesting stuff here, tracking how far time estimates are off to help predict a ship date.
• » Graphics card cracks passwords 25 times faster | IT News Digest | TechRepublic.com
  Not surprising — GPUs are way better at certain things than general purpose CPUs. Just means you have to make your password a little longer, that’s all.
• Software with a sense of humor - (37signals)
  The icon representing a PC in Leopard is a BSOD. Heh. Now if they could just get rid of the Marble of Death I end up looking at so often…

Call it a hunch, but I think this server will be fine as a virtual machine.