Wow.  Thanks so much, Kaleb.  I started looking into modifying that xhtml
file, and found those waters I waded into to be quite deep.  I only got so
far, but I came across mention of code signing that one would come across,
and how that security makes it difficult to make modifications.  With my
time being at such a premium these days, I decided to go with the more
expedient solution, that is, to set up a proxy server with at least one
custom error page.

Since we already use pfSense here, it didn't take much to find the path to
the Squid proxy error pages.  If anyone is interested, the English language
ones can be found here (many more languages are available from up one
level): /usr/local/etc/squid/errors/en

Below is a quick-and-dirty page I came up with.  The file is
/usr/local/etc/squid/errors/en/ERR_DNS_FAIL.  I thought of having an
automatic redirect, but I think it's better to require some interaction.

Thanks so much once again to everyone for their suggestions!

[image: image.png]


John Lolis
Coordinator of Computer Systems

100 Martine Avenue
White Plains, NY  10601
tel: 1.914.422.1497
fax: 1.914.422.1452

https://whiteplainslibrary.org/

*“I would rather have questions that can’t be answered than answers that
can’t be questioned.”*
— Richard Feynman
<https://click.fourhourmail.com/5qure95xkf7hvvo93wh2/7qh7h8h05vr4zrtz/aHR0cHM6Ly9lbi53aWtpcGVkaWEub3JnL3dpa2kvUmljaGFyZF9GZXlubWFu>,
theoretical physicist and recipient of the Nobel Prize in Physics in 1965


On Thu, 8 Feb 2024 at 17:39, Sove67 <[log in to unmask]> wrote:

> Hi John,
>
> Barring a more elegant solution, you could edit the .xhtml file that
> Firefox redirects to when it reaches a net error (you can view this by
> visiting the following "url" using firefox:
> *about:neterror?e=dnsNotFound*).
>
> The accepted answer here
> <
> https://superuser.com/questions/1792996/customize-file-not-found-page-in-firefox-114
> >
> explains where to find that .xhtml file, inside the omni.ja archive.
>
> I've attached a custom omni.ja archive you could inject, and examples of
> how it displays now vs how it used to display. If you plan to use this,
> please save a copy of the original omni.ja file that you need to overwrite!
>  omni.ja
> <
> https://drive.google.com/file/d/1aExDyrFxdE0svkRZELAA2Zg03PHXtnwo/view?usp=drive_web
> >
> [image: Example.PNG]
> [image: image.png]
>
> Best of luck,
> Kaleb A. (Langara LIT Student)
>
> On Thu, Feb 8, 2024 at 1:10 PM Lolis, John <[log in to unmask]>
> wrote:
>
> > Prithee, might one of you be able to point me in the right direction with
> > regard to modifying a browser error message, specifically a DNS
> error/site
> > not found message?
> >
> > Here's the rub... in an effort to prevent use of our OPACs as public
> access
> > computers, I've modified their DNS settings so that they only look to
> > themselves for DNS queries.  In their hosts file, I only added entries
> for
> > our catalog, our website and our museum pass reservation site.
> >
> > So this effectively prevents access to all other sites (unless of course
> > someone happens to know the IP address of another site).
> >
> > The problem is that the browser returns the DNS error/site not found
> > message, and there are no browser controls to go back since it's in kiosk
> > mode.  We have a label advising patrons to press ALT← to go back to the
> > previous page, but what I'd like to do is use a hex editor to modify the
> > default browser error to communicate the same thing.
> >
> > So my question is, does anyone know where I can find those messages so I
> > can edit them?  I've searched all sorts of Firefox files to no avail so
> > far.  I'm not completely averse to using a different browser, although my
> > preference is to *not* use Chrome or Edge.
> >
> > I also realize that whatever string I replace the error message with, it
> > must be the same length (this brings back memories of working at Prodigy
> > and editing command.com in MS-DOS so that it would return Bad command,
> you
> > idiot!!).
> >
> > hmmm... as I write this, now I'm thinking of utilizing a redirect page of
> > some sort, one that displays advice to the patron, then returns to
> > wherever.
> >
> > Thanks much!
> >
> > John Lolis
> > Coordinator of Computer Systems
> >
> > 100 Martine Avenue
> > White Plains, NY  10601
> > tel: 1.914.422.1497
> > fax: 1.914.422.1452
> >
> > https://whiteplainslibrary.org/
> >
> > *“I would rather have questions that can’t be answered than answers that
> > can’t be questioned.”*
> > — Richard Feynman
> > <
> >
> https://click.fourhourmail.com/5qure95xkf7hvvo93wh2/7qh7h8h05vr4zrtz/aHR0cHM6Ly9lbi53aWtpcGVkaWEub3JnL3dpa2kvUmljaGFyZF9GZXlubWFu
> > >,
> > theoretical physicist and recipient of the Nobel Prize in Physics in 1965
> >
>