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Locking yourself out horror stories

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Production servers usually have remote control device like DRAC or ILO so there are two network connection for the server.

This is very common problem, especially  if you access the remote server infrequently.  Often the time you need to access the server the password is already forgotten and the simplistic rule that you should not write down passwords blow up in your face. Generally, if regular passwords are used in the organization it is important to wear electronic watches with memo pad  (such as Timex Men's Ironman Data Link USB Watch   or  Casio Databank  watches ) that is capable of storing passwords. Cell phone also can be used unless you often forget it at home (I do). Sudo can (and should) be configured to provide opportunity for a wheel group to get to root.

Hosing Your Root Account

This was/is a common mistake on Solaris where the shell used for root is generally unusable for serious sysadmn work. Everybody and his brother are changing is either to bash to ksh. But errors in doing so lead to unintended consequences after the reboot :-).

Typically you get error messages like these:

    login: root
    Password:
    Login incorrect

This is why using sudo is important. If  wheel group is defined as equivalent to root and you are in this group you can fix the errors without typical tricks used for recovering root password or restoring access to root account.

Here is one recollection of this situation  (From: jdell@maggie.mit.edu (John Ellithorpe),  Massachusetts Institute of Technology

Here's a pretty bad story.  I wanted to have root use tcsh instead of the Bourne shell.  So I decided to copy tcsh to /usr/local/bin.  I created the file, /etc/shells, and put in /usr/local/bin/tcsh, along with /bin/sh and /bin/csh.

All seems fine, so I used the chsh command and changed root's shell to /usr/local/bin/tcsh.  So I logged out and tried to log back in.  Only to find out that I couldn't get back in.  Every time I tried to log in, I only got the statement: /usr/local/bin/tcsh: permission denied!

I instantly realized what I had done.  I forgot to check that tcsh has execute privileges and I couldn't get in as root!

After about 30 minutes of getting mad at myself, I finally figured out to just bring the system down to single-user mode, which ONLY uses the /bin/sh, thankfully, and edited the password file back to /bin/sh.

I'll never do that again.  This wasn't that much of a horror story, but good enough if you aren't that familiar with the system.


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[Oct 05, 2018] Trying to preserve connection after networking change while working on the core switch remotely backfired, as sysadmin forgot to cancel scheduled reload comment after testing change

Notable quotes:
"... "All monitoring for customer is showing down except the edge firewalls". ..."
"... as soon as they said it I knew I forgot to cancel the reload. ..."
"... That was a fun day.... What's worse is I was following a change plan, I just missed the "reload cancel". Stupid, stupid, stupid, stupid. ..."
Oct 05, 2018 | www.reddit.com

Making some network changes in a core switch, use 'reload in 5' as I wasn't 100% certain the changes wouldn't kill my remote connection.

Changes go in, everything stays up, no apparent issues. Save changes, log out.

"All monitoring for customer is showing down except the edge firewalls".

... as soon as they said it I knew I forgot to cancel the reload.

0xD6 5 years ago

This one hit pretty close to home having spent the last month at a small Service Provider with some serious redundancy issues. We're working through them one by one, but there is one outage in particular that was caused by the same situation... Only the scope was pretty "large".

Performed change, was distracted by phone call. Had an SMS notifying me of problems with a legacy border that I had just performed my changes on. See my PuTTY terminal and my blood starts to run cold. "Reload requested by 0xd6".

...Fuck I'm thinking, but everything should be back soon, not much I can do now.

However, not only did our primary transit terminate on this legacy device, our old non-HSRP L3 gateways and BGP nail down routes for one of our /20s and a /24... So, because of my forgotten reload I withdrew the majority of our network from all peers and the internet at large.

That was a fun day.... What's worse is I was following a change plan, I just missed the "reload cancel". Stupid, stupid, stupid, stupid.

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The Last but not Least Technology is dominated by two types of people: those who understand what they do not manage and those who manage what they do not understand ~Archibald Putt. Ph.D


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Last modified: October 05, 2018