All Collections
Librarian FAQs
Lean Library Dashboard
Support for EZProxy: Proxy by Hostname & Proxy by Port
Support for EZProxy: Proxy by Hostname & Proxy by Port

This article summarises Lean Library's support for the various EZProxy configurations

Daniel Horvath avatar
Written by Daniel Horvath
Updated over a week ago


EZProxy enables clients to determine the way URLs are rewritten. Generally speaking, two modes are supported:

• Proxy by Hostname
• Proxy by Port

OCLC provides a comparison in this help article and recommends Proxy by Hostname for its clients. A migration guide is provided here.

For comparison, this is an example of how URLs are rewritten:

Statement of Support 

Access feature

Access can support both configurations, as we will redirect users of a given domain, e.g., to the EZProxy Login URL. 

Assist feature

Assist is not affected by this configuration. 

However, if you want to show an Assist message on the proxied access, you would need to enter the proxied URL including the Port. It is our understanding that EZProxy will not be able to keep the port numbers stable, assigning port 2050 from our example to different databases at different times. So, this case is not supported.

Alternatives feature

Alternatives is fully supports Proxy by Hostname configuration.

Alternatives offers limited support for Proxy by Port configuration, making it necessary to disallow Alternatives for any proxied domain and thus disabling Alternatives for any off-campus user already proxied.

What to expect with Alternatives in an EZProxy Proxy by Port configuration

Imagine one of your users visiting from off-campus. Access will correctly offer to proxy the user, at which point the browser shows as the URL. 

Now imagine the user navigating to a specific article and reaches

As not all content at a given resource might be licensed, Alternatives will identify the DOI and check with your Link Resolver as to whether this article is licensed and at what location, no matter whether the user is currently proxied or not. It is a great way of making sure your users always reach the right access location. 

In our scenario, your Link Resolver might respond back with as the licensed access location. 

Alternatives will compare the URLs and see them as completely different and thus offer the user an Alternatives popup, taking the user back to the same page, creating an undesirable loop.

By blocking from Alternatives, we can prevent this from happening. However, if the article in the above example had been licensed at, we could no longer indicate this to the user.

Therefore, in order to guarantee the best results, we strongly recommend following the OCLC recommendation and utilizing the Proxy by Hostname configuration.

Did this answer your question?