In order to comply with CIPA, ESRL provides web filtering for staff computers, public computers, as well as devices that the customers connect to the library's wireless network.

Filtering System
The filtering system is a DNS based system, using software from, in conjunction with a commercial filtering list called jahaslist. We simply refer to it as nxfilter. The 2 proxies that ESRL maintains (filtered and unfiltered) are both using this new system. This system is resilient and scales significantly better than any other system we investigated.

Currently, these categories are blocked: Phishing/Malware, Warez/Torrent, Hacking, Porn, and Test (ESRL's testing category)

In addition to the filtering policy, all filtering also includes some antivirus, antimalware and anti-phishing protection. This protection is not expected to be perfect or comprehensive (none ever is) and is not a replacement for antivirus software or common sense.

Filtering on Staff Computers
ESRL suggests that staff computers, at a minimum, use our "unfiltered" filter which includes only the virus/malware/phishing protection. Staff computers may have stricter settings based on local library system policy.

Filtering on Public Computers
The filtering on library owned public machines is managed through Envisionware, and can be enabled or disabled (based on local library policy) through Envisionware. Envisionware - Dropping Filtering

Filtering on the Public Wireless
Filtering on the wireless segment cannot be disabled individually. If a customer needs an unfiltered connection they can be signed in to an unfiltered session on a public computer.

We are unable to filter any device that has its own data plan, only devices that connect to the library wifi.

What you see when content is blocked
The screen that you will see if a page is blocked by the filtering system looks like this:


The reason the page is blocked is given in parenthesis, in this case "Test".

Testing the filtering
ESRL has provided a test url that can be tried, to see if filtering is working properly at your site. That url is If you click this link, and see a message about BROKEN FILTERING, please contact systems @ esrl . org and let us know what went wrong.

Reporting a problem or wrongly blocked site
ESRL makes every effort to ensure that legitimate sites are not blocked accidentally; however no system is perfect. In the event that a legitimate site is blocked, or some other problem happens with filtering, contact the ESRL helpdesk and let us know about the issue.

Reporting a site that should be blocked
No filtering database is perfect, and new sites crop up all the time. If there is site that a user is going to that violates library policy (ie, porn), then make a note of the website and contact the ESRL helpdesk to let us know about the issue.


The "Category List" link takes you opens a new page describing all the possible filtering categories.