James J

Sysadmin/Engineer/Developer

Blog

01 Nov 2017

/dev/[u]random: entropy explained

  Entropy When the topic of /dev/random and /dev/urandom come up, you always hear this word: “Entropy”. Everyone seems to...

15 Oct 2017

smurf.c: The first DDoS attack tool (20th Anniversary)

  History Smurf.c(by TFreak) hit the spotlight 20 years ago this month(Oct 1997). To give you an idea of the...

01 Oct 2017

Cloud: Fully utilizing LVM in IBM Bluemix (Softlayer cloud)

  Backstory My apologies in advance I will likely use the names Softlayer and IBM Bluemix interchangably… For years I...

21 Sep 2017

sysstat: keep more than 30 days worth of sar data

  Being a good sysadmin, you should comb through your logs periodically… Even better, get a log analyzer. With that...

08 Sep 2017

VMware: bye, bye c# client

  The common use-case here is that you updated to ESX 6.5 and now you get this error when connecting:...

01 Sep 2017

strace: how do I even use this?

  Strace is one of those tools that can be quite intimidating. But if you dont know how to use...

16 Aug 2017

VMware OVFTool: new default to sha256?

  Dealing with quite a few different versions of VMware, I get quite a bit of indirect support work. Recently,...

30 Jul 2017

sysstat: run sar more than one time per minute

  While working on some issues with performance, we needed a bit more granularity than the 10 minute default that...

04 Jul 2017

VMware ESX 6.5: The provided manifest file is invalid: Invalid OVF manfiest entry

Set the stage: Recently while deploying an OVA that I had deployed many times before, I came across this error....

04 Jul 2017

RPM SPEC: Directives of interest

This is not intended to be an extensive guide to building rpms. Although, if there is interest, that can be...

19 May 2013

LVM: Slaving an old drive with existing data

I have an old drive with existing LVM data. The drive is plugged in as /dev/sdb. [root@bt ~]# fdisk -l...

12 Feb 2013

Named: Disable zone transfer(AXFR)

  Recently I have been watching my log files a lot more closely. While doing so, I noticed A LOT...

07 Jan 2013

LFTP: File Transfer Swiss Army Knife

Working in the industry, at one time or another, you will have to transfer files. Im sure it will be...

31 Aug 2012

N2N: Super simple VPN

So having a bunch of success with PF_RING, I decided to check out some of ntop.org's other creations. One I...

10 Mar 2012

RPM: Rebuild corrupt rpmdb

So this used to happen a lot… but since yum, not so much… Like an impatient admin, I got tired...

02 Oct 2010

Cisco 2960G: logging synchronous

Quite frequently, if you are running enabling debugging on something, it is going to be a little too verbose. Then...

02 Oct 2010

Cisco 2924XL: Port Channel

As part of a project I wanted to go ahead and setup port channels on my Cisco 2924s. Apparently on...