'''Symptom'''

  Forbidden:
  You don't have permission to access /cgi/wiki on this server

'''Mechanism'''

The web server either cannot run the wiki script due to temporary server overload conditions or your ip address appears on the webserver's deny by ip address list. The easy way to get onto this list is by overloading the server by requesting dozens of requests per second for hours at a time. Self-protection logic in the server detects this situation and adds your specific ip address to the deny list.

'''Rationale'''

"Spidering" the wiki looks like a DenialOfService attack to the server. It must reject requests without expending additional resources running scripts. The robots.txt file does not apply, because this is not a search engine problem. Usually, when this happens, someone has already gotten several thousand "can't sustain" messages (see WikiAccessUnsustainable). I get an email from the server whenever any new ip address is added to this list. I get several a day.

'''History'''

This self-protection was added to the server in 1999. At that time it was triggered once every week or so. Without the protection, the server could become so overloaded that I could not login remotely to correct it. 

From Sept 2004 to March 2005, I was forced to add abusing ip addresses to this deny list. I have since replaced this practice with WikiAccessRestricted. 

'''Recourse'''

If some other ip address is causing the problem, it will go away on its own. Try again in 10 minutes. If you or someone sharing your ip address has caused the problem, figure out who and what it was, then write me a nice note explaining what you've done to prevent further problems and I will remove the ban. Include your numeric ip address in the email.

-- WardCunningham

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See MoreAboutWikiAccess.