As different as night and tyres

For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))

I was going to say "as different as night and day" - but they're really too similar! You'll be reading this forum post on our new server, and I'm already seeing a dramatic improvement in performance - partly related to the heavy load on the previous server, partly because the previous server wasn't specifically tuned to our specific requirements, and partly because

it was physically located half a world away from us, which added in a lag time on each access no matter how fast and under loaded the network connection was. Map out the IP address that we're now using for www.wellho.net, and you'll be pointed to London, England!

Of course, we have grown to make extensive use of some very specific facilities over the years the site has been hosted in California - some of which were rushed in to short demonstrations which were intended to show a feature or facility rather to to be flexibly hosted, so a number of issued remain to be fixed over coming days, or finally transferred over the coming fortnight.

All sorts of issues with the upgrade (but no major software version issues - after all we do train people to be forward looking!) but I thought you might "enjoy" what is perhaps the most dramatic error message I can ever recall getting out of a Linux system:

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

@       WARNING: POSSIBLE DNS SPOOFING DETECTED!          @

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

The RSA host key for www.wellho.net has changed,

and the key for the according IP address 83.170.95.163

is unchanged. This could either mean that

DNS SPOOFING is happening or the IP address for the host

and its host key have changed at the same time.

Offending key for IP in /Users/grahamellis/.ssh/known_hosts:29

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!

Someone could be eavesdropping on you right now (man-in-the-middle attack)!

It is also possible that the RSA host key has just been changed.

The fingerprint for the RSA key sent by the remote host is

9d:8b:2d:0f:b8:17:fd:b3:24:ce:34:ef:de:cb:77:37.

Please contact your system administrator.

Add correct host key in /Users/grahamellis/.ssh/known_hosts to get rid of this message.

Offending key in /Users/grahamellis/.ssh/known_hosts:1

RSA host key for www.wellho.net has changed and you have requested strict checking.

Host key verification failed.

earth-wind-and-fire:~

And what caused that? Well - it could have been paraphrased into:

You're in touch with a different machine to the last time you contacted www.wellho.net. Are you sure this is right? and of course, in the circumstances, I am sure ;-)

The solution? Either delete the offending line from the known_hosts file (that :1 in the message means that it's line number 1) or - as I did (but should not admit) just clear down the .ssh directory and reauthenticate all hosts next time you connect to them!
(written 2008-07-18, updated 2008-07-23)

Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles

A163 - Web Application Deployment - Network Configuration and Security
  [11] A bolt of lightning on Multicasting - (2004-08-11)
  [37] Security and Safety - (2004-09-03)
  [267] Searching security holes - (2005-04-04)
  [332] Looking up IP addresses - (2005-06-01)
  [506] What are DHCP and DNS? - (2005-11-27)
  [511] Domain Forwarding - 2 ways of doing it - (2005-11-29)
  [1073] Heartbeat script in Perl - (2007-02-09)
  [1408] Wireless hotel tips - FTP and Skype connections failing - (2007-10-26)
  [1666] Slow boot and terminal start on Linux boxes - (2008-06-05)
  [1904] Ruby, Perl, Linux, MySQL - some training notes - (2008-11-23)
  [2052] How was my web site compromised? - (2009-02-24)
  [2489] Parallel Pinging, using Python Threads or Expect spawn lists - (2009-11-02)
  [3448] Checking all the systems on a subnet, using Expect and Tk - (2011-09-18)
  [4134] Setting up your MacBook Air as a mobile broadband router - (2013-07-07)

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Rapid growth leads to server move

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Ways to accept credit cards - or not!

Some other Articles

Larger applications in PHP
Pictures from South Hampshire
Hillier Gardens, Hampshire
Ways to accept credit cards - or not!
As different as night and tyres
Rapid growth leads to server move
At the Westbury Bypass Enquiry
There is more that one way - Perl
A Train Service Update for Melksham Party in the Park
Configuring Apache httpd

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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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