This brief help document provides guidance on how to get the most out of the Modify Headers extension.
Table of Contents
- What’s New?
- FAQ
- Quickstart
- Adding Headers
- Modifying Headers
- Filtering Headers
- Using Multiple Instructions
- Reordering headers
- Configuration Options
Donate
Please consider making a contribution to support the development of Modify Headers.
Defects and Enhancement Requests
Please post bugs and enhancement requests to the Modify Headers bugzilla.
I’m very appreciative of the work you’ve done on this extension, but
aaaaaaaaaaaaaaaaaaaaargh
you’ve made it impossible to open it in a tab on OS X now. :o(
Or am I missing something?
Matt, Thanks for taking the time to provide feedback.
I switched the window to be a prefwindow instead of a standard dialog. This was so I could take advantage of the toolbar at the top of the page that prefwindow provides. However, there was a problem with prefwindow on Macs where the window resizes to the content even when opened as a tab.
I’m working on tracking down a way of overriding this behaviour and restoring the open-as-tab option. Please be patient while this is worked out.
Will do, thanks.
If you can’t do the tab, is there any way of making the window resizable? I have 177 headers in my configuration, with user-agent values that would be much easier to read if the window was larger.
Hi Matt, Please take a look at the beta available at https://addons.mozilla.org/en-US/firefox/addon/967/. I believe I have overcome the problems with Open-As-Tab and making the window resizeable. Please test the beta and provide feedback.
Thanks, pls how do I make it support https sites
Hi Tecky, you may have problems if you access HTTPS sites via a proxy. This defect is being tracked here: https://www.mozdev.org/bugs/show_bug.cgi?id=22493. If you have further comments, please do so on the bug.
Re-sizable window is a must, i have hundreds of headers as well. I do not see the same window that is in the screenshots. There is no configuration tab and help is in a different area. I also work with 20+ windows open so having modify headers in its own tab was great, please go back to that. I would not have gone with the update had I known. If it ain’t broke, don’t fix it!
Scott, I’ve added a blog entry that details the reasons for the changes. The short story is that I wanted to get a release out and had some problems with open-as-tab and resizeable with no solutions. I choose to release anyway and fix them later. Thankfully, I got lucky and managed to work them out in a just a few days. Release 0.6.9 has been uploaded to Mozilla Addons and is pending approval.
Hi! I really like the MH extension, actually many of us have to use it in Poland if we want to get rid of compression applied by the ISP… Anyway, it would be perfect to have the button somewhere in the toolbar (e.g. as for AdBlock Plus) to have the possibility of immediate turn on/off all rules. I mean just the functionality of “Enable All”/”Disable All” under a button directly in the browser, without going into menus.
Do you think it is possible? Is it a big effort to implement it?
Thanks in advance!
Hi Darek, I’m very glad you like the extension. The feature you mention should be straightforward and has already been requested here: https://www.mozdev.org/bugs/show_bug.cgi?id=23473. One obstacle to a status/addon bar icon is that I am not a good designer and have terrible ideas when it comes to graphic design.
I do want to get a logo for Modify Headers and will very soon be looking for a designer to help out.
Just got the update and very pleased to see MH open in a new tab.
Thanks!
Hi,
There is a problem from the last update 0.7.1.0:
I usually keep the status bar (add-on bar) hide, but from this update it reappears every time a new window is open or Firefox restart.
Also “open in tab” has a issue to, I fix it from “about:config” modifyheaders.config.openNewTab=true
Cheers!
I created a bug for the toolbar problem: https://www.mozdev.org/bugs/show_bug.cgi?id=24593. Please add a comment describing your platform and Fx version.
As for “open in tab”. I tested this on Mac and PC with no problems.
Version 0.7.1.1 provides a fix for the addon toolbar.
Hi Gareth,
Thank you very much for that fix 😉
I usually keep the addon bar unhidden but can’t keep the Modify Headers icon out of it. Customize and remove the icon, but every time a new window is opened, the icon reappears. I’m using version 0.7.1.1.
Cheers!
This is high on my list of things to fix. Please see this bug: https://www.mozdev.org/bugs/show_bug.cgi?id=24847
Modify Header is not anymore under Tools pull down menu. It’s at Add-ons (active_not disabled). Under options its Enabled. But when you open for example South Park or Jon Stewart Show the the video it’s not available for viewing in Canada. This after Nov.27.
The menu option moved to Tools -> Web Developer -> Modify Headers. Use the icon in the top left of the window to start/stop the addon. There is also a quick menu in the addon toolbar.
Take a look at the Quickstart page.
Modify-Headers no longer run as when after entering
the different x-Forwarded it is impossible as before
to obtain the case ” always on” as Headers in mark in
blue and no longer useful.
Excuse my bad english as I am living in Belgium.
Thanks for an answer
Yours truly
“Always On” was replaced by a Start/Stop button due to popular demand. Click the icon in the top left of the Modify Headers window to start/stop.
Hi Gareth,
I\’m using modify headers 0.7.1.0 with FF 8.0 and can\’t seem to watch the daily show anymore. Earlier in the day before I \’updated\’ it was working fine. After restarting in the afternoon I can no longer watch the daily show. How can I rectify the problem?
thanks
Make sure you have clicked the new icon in the top left of the window. This will start Modify Headers – the icon will turn red. The addon will continue to be on until you press the same button to stop, the the icon will return to a grey colour.
Oh no, I’m lamenting loss of always-on.
I really dislike the start-stop thing; I have to do it for every new window that opens.
I wonder if I can try to roll back to an old version of the plugin. Which version number should I look for?
some background:
– I’m in the UK and I always use FireFox to watch American stuff (like Daily Show, Colbert Report, South Park)
– I’m using Mac OS X Lion.
Thanks for all your hard work, Mr Developer (aka Mr Hunt)
Gareth,
I feel it’s really important to always be able to see the status bar, as phishing is so prevalent. When the stop/start bar appears it seems to kill the status bar (the one showing the full URL of a link when you hover over it, for example)
Can you PLEASE PLEASE PLEASE PLEASE give us the option to use always-on, and disable the start-stop bar. (Pretty-please with sugar on top)
?
Hi Chris, the “start/stop bar” as you call it is actually the standard Firefox addon bar – Modify Headers adds a button to it. There is a bug where the addon bar is displayed with every new window opened. This bug is fixed in version 0.7.1.1 (http://bit.ly/tS7MRX) and should be approved by Mozilla soon.
Finally, please understand that the Start/Stop button is the always-on feature under the covers but with a different UI. Once you press “Start”, Modify Headers will continue to be on until you press “Stop”, even between restarts. Please remember that Modify Headers is primarily a web developer tool. Web devs needed a better way to enable and disable the addon while they worked.
As for the addon bar covering the status bar, that surprises me. I took a look and can see the URL displayed above the addon bar when I hover over a link.
Hi Gareth!
I love this addon! One thing I can’t achieve is header without “HTTP_” prefix. I’m writing a mobile site and I need to add UAProf headers like: “X-WAP-PROFILE” or “19-profile”. I see that when I create header called “PROFILE” then on the hearers list HTTP_PROFILE is added. Can you give an option for not adding this prefix?
cheers
tk1
Hi tk1,
Actually Modify Headers is not adding this prefix. I assume you are listing the headers received server side using PHP or some other platform. The “HTTP_” prefix is added by the server side platform to identify this is a HTTP request header. For example you configure PROFILE in Modify Headers. The server receives PROFILE in the HTTP headers, but PHP lists it as HTTP_PROFILE.
I hope that makes sense.
Perhaps I’m missing something, but I followed the quick start tutorial and then activated Modify Headers, and I don’t see anything different when browsing? Perhaps I assumed this add-on does something that it does not – shouldn’t I see what an iPhone would see when I add the iPhone profile in the tutorial? I don’t see any explanation on this site as to what I ‘should’ be seeing. I certainly don’t understand the mystic details of headers, but want to do some mobile browser testing.
Scott. You will only see something different if the website you visit has a mobile version. When I get some time, I’ll update the quickstart and add an example of the difference you will see.
I remember with older modify header versions, this extension was active by default. Now I have to manually activate it and unfortunately sometimes I forget. Is there an internal configuration switch that can be set perhaps via the FF about:config to have the extension enabled by default?
Modify Headers was never enabled by default. There used to be two ways it was enabled:
This was changed to a Start/Stop button so there is only a single way for the add-on to be enabled. If you want Modify Headers to be active all the time, simply click the Start button so the icon goes from grey to red.
Sorry, I was wrong in my yesterday’s comment that the extension doesn’t work. It does, and it’s a lifesaver now that Firefox removed Accept-Charset! It didn’t work because I didn’t press “start”. Please don’t assume that non-standard controls are easy to find. If you had a standard button in the dialog, I would have found it. I didn’t expect a picture on top to work as a button.
The UI is something I have struggled with. Ideally there would be a single way to enable and disable headers. I’m working on figuring this stuff out, but it’s not as easy as you’d think. I’m always open to suggestions.
Adding headers doesn’t work with Firefox 10. I’m trying to add Accept-Charset, but I don’t see it in Wireshark dumps.
Hi
In the next release, can you add a whitelist of website no affected with modify header ?
Thanks,
Good idea. I’ve created a bug for this: https://www.mozdev.org/bugs/show_bug.cgi?id=25194
Hi Gareth,
I’m excited about this application and I have some questions:
1) When I follow the instructions in the FAQ and change my user agent to iPhone and then navigate to the google.com page, I can see that google is detecting my user agent and is serving up a different page, however the browser window is not automatically resized to the size of the display on the cell phone I’m attempting to emulate. The reason I want the browser window to match the size of the device I’m testing is to make sure that the website I’m testing does indeed fit within the screen of the mobile device I’m emulating. In other words, if I’m testing a website to see how it looks on a Motorola Triumph phone, I need to make sure that the site isn’t too big to fit in the Motorola Triumph’s display. So this is my first question: is there a way to get the browser window to resize to the correct size for the emulated mobile device?
2) My second question is, I was emulating an iPhone and I went to a site that contains a lot of Flash components. As we all know (and most of us dislike), the iPhone does not support Flash, yet the site and its Flash components displayed just fine. So my next question is, how do I get Modify Headers to emulate the plugin capabilities of the device being emulated?
3) My third question is, while emulating an iPhone (per the example in the FAQ), when I navigate to google.com, the site does indeed serve up different content based on my browser, however when I turn off emulation in Modify Headers and reload the google.com page, it still serves up the page as if I were using an iPhone, instead of Firefox on the Mac. This issue does not occur with the google.com site if I’m emulating a Motorola Triumph in Modify Headers; in that case, google.com serves up the correct page for Firefox/Mac or Motorola Triumph as I toggle emulation on and off using Modify Headers and reload the page. So my final question is, how can I toggle off emulation of the iPhone in Modify Headers, other than quitting and relaunching my browser?
Thanks for a great app!
Scott Janssen
Hi Scott,
Thanks for the questions. Modify Headers is not a mobile device emulator, it is a means to spoof HTTP request headers including the User-Agent. However, you can use a combination of other addons to achieve the effect you are looking for.
Hope that helps (and sorry it took so long).
Great Add-On, but my experience combined with other comments suggests many are misunderstanding the user interface:
When I saw that my user-agent mod was Enabled, with a green light next to it, I naturally expected it to work. Wrong. You have to go into another Tab and select “Always On”. I hadn’t selected this as I assumed that it would enable my modifications next time I started, rather than be a plain On-Off switch.
I think the various commenters on referring pages around the web who say this doesn’t work are suffering from the same problem.
Please could I suggest moving the On/Off to the front page of the preferences and give it substantial prominence – and perhaps even ask if you set up something and don’t turn it on?
I can understand how this is confusing for some users. The red/green toggle is supposed to indicate whether headers will be modified when the add-on is ‘started’. Clearly from feedback I’ve received this is not understood.
I am working on changes to the add-on that should make life simpler. If you want to see those changes as they happen, please sign up for the addon beta channel. The current version there is a year or so old, but I will be pushing newer versions soon.
Hey,
I remember having Modify Headers available under “Extras” (don’t know what it’s called in english), the menu tab to the right of the bookmarks tab, where you can start private mode among other things.
Well, now I am unable to get MH there. Is it possible? Is it gonna be a feature in the future? *g*
Thanks in advance!
I plan on adding options for where you can see Modify Headers. Stay tuned.
I use this add-on for my job to test if a DNS change is going to work by adjusting the Header and pointing my browser to the IP the DNS will be changed to.
I love being able to do this!
The only problem I have is that I sometimes forget to turn the add-on off, effectively breaking all other websites I visit. Not immediately seeing what has created this problem has lead to some embarrassing moments including having to explain how I broke my Internet with a third party plugin.
To fix this problem I would really like the option to have the plugin automatically turn off after visiting one site or to have the plugin be contained to one single tab.
This bug was opened to add a whitelist/blacklist. I think this would be of help to you: https://www.mozdev.org/bugs/show_bug.cgi?id=25194
Can this also be used to modify the headers _sent_back_ by the web site, before they are passed to further processing in Firefox?
Indeed, this tool would be very handy to work around bugs such as 567365 (“Cache-Control no-cache on https page disables history”) and 288462 (“[Meta] Mozilla sometimes re-retrieves pages instead of re-using already-retrieved copy; violates RFC 2616 (Back, Send Page, etc.)”)
If we could replace every incoming Cache-control: no-store or Cache-control: no-cache header with an expires=0;must-revalidate, history would work again!
There is an enhancement request for this:https://www.mozdev.org/bugs/show_bug.cgi?id=18455. It’s not high on the priority list as I want to add header groups for specific sites and fix the usability problems first.
A major feature it’s lacking is the ability to limit rules to a domain.
As a web developer, a use case would be to assign “Host: http://www.domain.com” when visiting a page on “http://host-ip-address-here/”, effectively allowing access to a legacy website after a new site launches in its place.
Gareth, I just noticed your reply to the comment above. Header groups for specific sites would work perfectly
When do you expect to have that feature released?
I don’t have an ETA for delivery of this feature. I wish I could provide a better answer
This feature is on the roadmap, however there is no ETA for delivery.