Just download webproxy/error.html file form webproxy folder located on your router. Edit it as a standart HTML file. And upload it back where it was.
Worth pointing out that that file doesn't appear automatically (at least on any system I've tried it on) and I had to click on 'Reset HTML' in the web proxy settings window in Winbox.
I notice that the page http://wiki.mikrotik.com/wiki/Manual:IP/Proxy
covers a lot of the settings, but not all - why does "cache-hit-dscp", for example, not have a description?
That page also does not cover the content of the file webproxy/error.html. On my system it is created with the following content:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html><head><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<hr noshade size="1px"/>
<p>While trying to retrieve the URL <a href="$(url)">$(url)</a>:</p>
<p>Your cache administrator is <a href="mailto:$(admin)">$(admin)</a>.
and I have the following questions:
- Why is there a section in an 'if error' clause? Is there any condition where the error.html file which says "ERROR" in it isn't an error and this clause does not apply?
- What are the possible options for '$(status)' - it would be nice to edit that page to have some explanation for the user.
- Where is '$(signature)' defined? I would like to be able to remove 'Mikrotik HttpProxy' from the message to make it more personalised for the end user.