Squid Web Cache wiki

Squid Web Cache documentation

πŸ”— The risks that come with using StoreID

I would like to describe some of the risks that comes with maintaining a cache.

The basics of information security are Confidentiality, Integrity, and Availability.

πŸ”— Confidentiality

Since HTTP we are talking about, there is a real issue with reading and sharing URLs and other info.

I remember that there was a professor that could tell what OS and what OS specific version the TCP packets on a tcpdump came from.

So a far more detailed information can be extracted using a proxy access.log or cache.log.

It requires the cache administratr to be a person that can be trusted with all this information.

πŸ”— Integrity

While operating a cache there is a very tempting way to alter data or over-cache it.

The above can violate the integrity of the response to the client request.

πŸ”— Availability

A cache do allow over availability which should not impact anyone of the users.

The whole purpose of a caching proxy is to allow the above and the cache admin should make sure the cache is bringing availability and not the opposite.

πŸ”— Several real world examples

To allow you understand the meaning of the above I would describe a scenario.

These issues are major problems for end users and businesses trading on the Internet. Some can even endanger lives. They are caused by bad proxy configuration, yet the proxy administrator will very rarely ever be told about the problem. Since the proxy is making it appear to be a broken website - the website administrator will face all the complaints.

πŸ”— ISP

A user tries to write a small article while the page loads up and after reading two pages long the date that the professor told this poor user to read was not the date of the delivered article.

A very fast F5 or SHIFT-F5 or CTRL-F5 changes the page contents and the poor user understand that the page was updated two weeks ago (the professor talked about the latest released paper.. ).

πŸ”— Medical Facilities

When life at stake an MD or another assisting force can get some information faster and by that squid is a direct life saving assisting tool.

This is the place to alert cache admins to be carefulness with cache settings since they can harm almost directly a patient and others.

Examples for cases which was seen in the past when a cache was configured wrongly in a medical facility:

πŸ”— Police, Army and National Security

Police might be able to use squid as a forensic evidence tool that will help to catch pedophiles, arms dealers, drug smugglers and many other things which might exist out-there.

Army and National Security can use squid to assist realtime applications take the HIT when there is a need for spreading public alerts or to be gateway to soldiers assisting devices and services.

πŸ”— Parenthood

Pictures that parents do not want shown their child shows up on a clean site since there is a problem with the StoreID algorithm pattern matching the clean site with another porn site pattern.

πŸ”— Bank/Trade

A bank account page that is not up-to-date will make the poor users buy something he can’t really pay for.

Administrators choosing to ignore caching rules on images causes wrong captcha picture to be delivered to users. Entering the embedded text in the captcha login does not work properly. Blocking users from accessing their banking accounts or making online purchases.

πŸ”— Conclusion

There is a risk in maintaining a cache and there are benefits.

We are humans and we have the right to do a mistake two or more but we are obligated to do our best.

When configuring refresh_pattern , url_rewrite_program , store_id_program , ICAP service/client or any other feature sit.. eat a good meal, drink a good drink. Then when you are full with power sit on whatever you are supposed to do in order to make it the best you can.

πŸ”— How all the above is even related to Squid?

I would imaging that after hearing someone having troubles with the Internet and then a small F5 fix it would make sure to understand it all.

Since I am the author of StoreID I would say that it can help to make the WWW faster and one level up more reliable.

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