I run a website for a small company. The websites mostly contains text and images. Whenever i update the website by replacing a image or updating the css, it doesn't get updated on other people's browsers because it's been cached. I've found a way to get around this by adding a version number where i'm linking my stylesheet, however, this doesn't apply to images. What is the most simple way to get around this?
I've done a lot of research on the web and on stackoverflow, but they are all complicated solutions. There must be a better way.
Just to be clear, i know i can clear the cache in my browser. I'm looking for a solution that works for everyone who access my website.
You can add these meta tags and it will force a page to reload from the server on every reload. However, you should realize that this could result in a lot more data usage for both you and your users.
<meta http-equiv=“Pragma” content=”no-cache”>
<meta http-equiv=“Expires” content=”-1″>
<meta http-equiv=“CACHE-CONTROL” content=”NO-CACHE”>
If you have a reload link or button on your html page, you can add this attribute to it to force a reload from the server. The 'true' parameter is what forces a full reload instead of a cache reload.
onClick="location.reload(true);"
You can rename your images (preferably) automatically when you want to avoid them being cached, adding a version number to their name. If you have something which does this automatically, then you bypass the problem of caching them.
If you want to keep the name of your images, then you can make the change only temporary.
Try versioning(?version) to the files to avoid browser caching.
it will be like filename.jpg?v1 filename.jpg?v2
Or if you are replacing files frequently try adding current timestamp for every page load
In php,
filename.jpg?<?= time()?>"
where time() is current timestamp
This means you are just changing the urls everytime.
so, i was checking some web page source code and I've noticed this at the end of some CSS links and images :
?asset_version=
and also this ?v=
What is their role ?? sorry for the English.
Thanks
This tends to be a solid way to force browsers to fetch a new version of a file if you modify it. Often, browsers will not respect the cache-control header specified, or you may not have the option to configure that (for example, a limited shared hosting environment). In that case you simply modify the URL by incrementing a version number, which convinces the browser it's a new version, even though it will likely return the same file.
as far as the browser is concerned, resources/css/application.css?v=1 and resources/css/application.css?v=2 are different files, even if the css file itself is totally unaware and uncaring of the trailing query parameters.
They are used for cache busting. Most web severs will tell a browser to hold onto various resources like image, css and javascript files so that on the users next visit they do not have to be downloaded. By appending a version control value they can force the browser to download the newer versions, otherwise the browser might not download the newer files because it still has a version that's within the time frame it was told to hold onto the same file for the domain.
The process might go a little something like this:
Hold onto my CSS file for 180 days, <link href="path/to/css/style.css">.
30 days later I update my CSS file. Browser will want to use the one you already gave it as it's valid for another 150 days. But you want it to use the newer version so you use a cache busting technique. So you might do this <link href="path/to/css/style.css?v=09252015">.
The browser uses the complete path to identify resources from a domain. Changing the query string value effectively makes the browser think it's a different file.
You will also come across people cache busting in the actual file name also.
<link href="path/to/css/style-09252015.css">
I am building a website with at least 7 pages and am looking for a way to avoid having to repeat all headers & footers etc. on every single html document.
I know there are frames and iframes but some browsers don't support these and I want to do something more efficient and flexible for updates. Any ideas/suggestions?
Thanks for the information guys! I'll be sure to try them out.
One more thing is that I have a login form within my header. Will these methods affect it?
Regards
Yes, server side includes are the way to go, just a few clarifications:
1) You can do it as described by Sotiris if you choose to use PHP - which is very common choice, and btw.virtually all hosts support php.
2) Although the file will have extension .php, you can put your pure html code in it.
3) To be able to test and see this on your computer before uploading it, you have to install server on it. At this point I think it's simplest and fastest for you to go for some ready made solution - these are downloadable free:
http://www.wampserver.com/en/ (for Windows)
http://www.mamp.info/en/index.html (for Mac)
http://tuxtweaks.com/2010/04/installing-lamp-on-ubuntu-10-04-lucid-lynx/ (for Linux)
you can create a php file that will include all required code (for example footer.php). Then you can link it adding in every page in the proper place the following code (if you want to add the footer for example):
<?php include "footer.php"; ?>
If it is static HTML pages that you are builing, you probably want to think about Server Side Includes
http://en.wikipedia.org/wiki/Server_Side_Includes
How to prevent downloading images and video files from my website? Is it possible?
What would be the best way to do this?
No, it's not possible.
If you can see it, you can get it.
Don't post them to your site.
Otherwise it is not possible.
As the browser needs to transfer the content to display it (text, images, videos), the data is already on the client's computer when the website is displayed. The previous answers give little advice on how to make it harder for non-experienced users to grab the content. Here are some directions:
General
Overlay the respecitive contents with a transparent <DIV> or a
transparent image (as described in some answers to this question)
Open the website in a frameset, so saving may miss the frame content.
Open the website via window.open() to hide the menu bar.
Disable right-clicks via JavaScript (not recommended due to all the side-effects on usability)
Load the page's HTML code from another file (which may check for a specific referer or which may be ROT13) via JavaScript, so it's harder to access the source code.
Tell the browser that all content is display:none for the printer (something like #media print { body, div, p { display: none } })
Use JavaScript to hide the content before a client makes a screenshot (see Stop User from using “Print Scrn”)
Try to disable or overwrite the clipboard (see this post)
Images
Do not use the <img> tag for images but set the image as background for a <DIV>
Wrap images into SVGs or Flash movies to make them very hard to access in a usable format.
Disable caching for images (via <meta> tag or by setting the appropriate header on server delivery), so they are not stored in the browser cache (immeaditely accessible on the client's computer).
Cut an image into parts, so it takes some extra work to reconstruct the whole image
Add onmousedown events to images, e.g., display a copyright alert.
Deliver the image via server script (e.g., PHP) and check the referer.
Videos
Stream videos to prevent simple downloading via URL.
Wrap videos into a Flash movie.
Use some nasty format that supports DRM.
Texts
Make text unselectable (see How to make HTML Text unselectable)
Additionally to overlaying, wrap the text into JavaScript (e.g., after ROT13 or loaded dynamically from a second file), so the text is not directly available in the source code.
Convert texts to images (this may decrease display quality), SVGs or Flash
Again, I repeat that none of this will stop an experienced user from grabbing the content (e.g. by making a screenshot and - optionally - run OCR on it). Sometimes it's as easy as using the browser's developer tools or using the website without JavaScript. Yet, it will give inexperiences users a hard time, so they may look for some easier source to grab from.
Also keep in mind that the above techniques will affect search engines when reading the page's content (if you're interested in blocking them, start with a robots.txt).
Thank you for any other ideas to complement the above list!
Images must be downloaded in order to be viewed by the client. Videos are a similar case, in many scenarios. You can setup proxy scripts to serve the files out, but that doesn't really solve the issue of preventing the user from getting their own copy. For a more thorough discussion of this topic, see the question How can I prevent/make it hard to download my flash video?
If you are using PHP, the best way is to control it the .htaccess, you need to put your files, images and videos under consideration in a separate folder/directory, and create a new .htaccess file in this directory with the below:
RewriteEngine On
RewriteCond %{REQUEST_URI} \.(mp4|mp3|avi)$ [NC]
RewriteCond %{HTTP_REFERER} !^http://sample.com/.*$ [NC]
RewriteRule ^.* - [F,L]
The first line %{REQUEST_URI} will prevent getting the file through the web browser or through curl.
The second line %{HTTP_REFERER} will prevent accessing the image/video using HTML tags <img> or <video> from any website except the exception ! you provide instead of http://sample.com/ which usually should be your website itself.
You can also have a look at my question and the accepted answer here for more tricks on the browser side.
I'd like to add a more philosophical comment. The whole intent of the internet, particularly the World Wide Web, is to share data. If you don't want people to download a picture/video/document, don't put it on the web. It's really that simple. Too many people think they can impose their own rules on an existing design. Those who want to post content on the web, and control its distribution, are looking to have their cake and eat it too.
In short, no. If someone can view an image or video in their browser then they have, by definition, downloaded it. That's how the web works - it is client server based. Whatever you can view in your browser (client) has been transfered to your computer from the remote website (server).
In standard HTML, I don't know of anyway.
You didn't really say, but I'm guessing you are having problems with people deep linking into your content. If that's the case, and you are open to server side code, I believe this might work:
Create a page that accepts a numeric
id, maps it to a server file path,
opens that file, writes the binary
directly to the response stream.
On the page request, generate a
bunch of random ids, and map them to
the actual media urls, and store that
mapping object server side somewhere
(in session?) with a limited life.
Render your pages with your media
links pointing to the new media page
with the appropriate id as a query
string argument.
Clear the mapping object and generate
all new links on every postback.
This :
won't stop people from downloading
from within your page
definitely isn't as lightweight as standard
HTML
and has it's own set of issues.
But it's a general outline of a workable process which might help you prevent users from deep linking.
As many have said, you can't stop someone from downloading content. You just can't.
But you can make it harder.
You can overlay images with a transparent div, which will prevent people from right clicking on them (or, setting the background of a div to the image will have the same effect).
If you're worried about cross-linking (ie, other people linking to your images, you can check the HTTP referrer and redirect requests which come from a domain which isn't yours to "something else".
you can reduce the possibility but not eliminate it...
It also doesn't hurt to watermark your images with Photoshop or even in Lightroom 3 now. Make sure the watermark is clear and in a conspicuous place on your image. That way if it's downloaded, at least you get the advertising!
This is how I do it in case anyone in the future is wondering.
I put this in the .htaccess file on the root server:
RewriteEngine on
RewriteCond %{HTTP_REFERER} !^http://(www\.)?domain.com/ [NC]
RewriteCond %{HTTP_REFERER} !^http://(www\.)?domain.com.*$ [NC]
RewriteRule \.(mp4|avi)$ - [F]
This stops them from say going to domain.com/videos/myVid.mp4 and then saving it from there.
No it's not. You may block right-clicks and simillar stuff but if someone wants to download it, he will do so, trust me ;)
As soon as they view your page that includes the picture or video, the item is downloaded into the temporary folder of their browser. So if you don't want it downloaded, don't post it.
You can mark folders or files so that they don't have read access (any of the main web servers support this). This allows you to store them on the server without any level of access to the outside world. You may want to do this if you have a service that generates images for someone else to download later, or if you use your web account for FTP access, but don't want anyone to view the files. (i.e. upload a .bak file to the server for someone else to FTP down again).
However, as others have said, getting into copyright areas where people can view the image or video but not save them locally is not fully possibly, although there are tools to discourage illegal usage.
Put your image or video in flash format. Works great.
This is an old post, but for video you might want to consider using MPEG-DASH to obfuscate your files. Plus, it will provide a better streaming experience for your users without the need for a separate streaming server. More info in this post:
How to disable video/audio downloading in web pages?
I believe THEOplayer already provides this sort of solution as a paid service, but I'm not so sure about it.
Granted that any image the user can see will be able to be saved on the computer and there is nothing you can do about it. Now if you want to block access to other images that the user is not supposed to see, I am actually doing it that way:
Every link is to the "src" in your image tag is in fact a request
send to a controller on the server,
the server checks the access
rights of that specific user, and returns the image if the user is
supposed to have access to it,
all images are stored in a directory
that is not directly accessible from the browser.
Benefit:
The user will not have access to anything that you don't intent him/her to have access to
Drawback:
Those requests are slow.. especially is there are lots of images on the same page. I haven't found a good way to accelerate that in fact..
You can set the image to be background image and have a transparent foreground image.
I think the best way is:
STREAM THE VIDEO IN SEPARATED ENCRYPTED PARTS.
There are video hosting services such as vzaar that have this functionality.
As far as I know, that will make it really hard to download directly. At least for 95% of the people.
But of course, if the video plays on the screen people can just use a screen recorder and some simple software to record sound from the audio output (but he/she will have to play the ENTIRE thing to save it, totally inconvenient).
You can't stop image/video theft but you can make harder for normal users but you can't make it harder for the programmers like us (I mean thieves that know little web programming).
There are some tricks you can try:
1.) Using flash as YouTube and many others sites like http://www.funnenjoy.com does.
2.) Div overlaping or background pic setting (but users with little sense can easily save all resources by opening inspect element or other developer option).
3.) You can disable right click and specific keys like CTRL + S and others possibles with JavaScript but main drawback is that if user disable JavaScript our all tricks fail down.
4.) Save image in none online directories (if you have full access to web server) and read that files with server side languages like PHP every time when image / video is required and change image id time to time or create script that can automatically change ID after every access.
5.) Use .htaccess in apache to prevent linking of your images by others sites. you can use this site to automatically generate .htacess http://www.htaccesstools.com/hotlink-protection/
Insert a transparent gif 1px x 1px just inside the <body> tag:
<body><img src="route-to-images/blim.gif" class="blimover">
Then style it with this:
.blimover {
width: 100% !important;
height: 100% !important;
z-index: 1000 !important;
position: absolute !important;
top: 0 !important;
left: 0 !important;
}
This will remove any click functionality from a page, but it sure stops people stealing any content!
You can apply the same to a <div>, <section>, <article> etc, just name accordingly and prevent your copy and/or images being ripped.
Nothing stops a screengrab though ... ...
If you want only authorised users to get the content, both the client and the server need to use encryption.
For video and audio, a good solution is Azure Media Services, which has content protection and encryption. You embed the Azure media player in your browser and it streams the video from Azure.
For documents and email, you can look at Azure Rights Management, which uses a special client. It doesn't currently work in ordinary web browsers, unfortunately, except for one-off, single-use codes.
I'm not sure exactly how secure all this is, however. As others have pointed out, from a security point of view, once those downloaded bytes are in the "attacker's" RAM, they're as good as gone. No solution is 100% secure in this case (please correct me if I'm wrong). As with most security, the goal is to make it harder, so the 99% don't bother.
I think the best way is to prevent right clicking on your webpage, because that is the most convenient way a normal user try to download the content, and you can consider it as remark if u able to do this only as you are never gonna be able to stop a computer geek or hacker people from downloading it, because once the content is on the internet, it means it is in the public domain already...
Put the content on google drive and make it download protect. This way people can only see your documents, pictures but cannot download it.
DRM solutions are available today. It makes the video viewable but not downloadable.
What is DRM?
Digital Rights Management (DRM) solutions are software programs created to help people protect and control their valuable digital content, whether it's documents, videos, images, or audio files.
Check out this. Hope it's helpful.