Eric lippert - Amazon Web Services

NETWORK_SERVICE, IUSR and IIS APPPOOL\.
• Enable Static and Dynamic Compression.
• Turn on Content Expiration from IIS > Website > HTTP headers
> Common Headers. Set to 30 days. This makes all the static file
cacheable on the browser. You will get significant reduction in web
traffic when you turn this on.
• From IIS > Website > Bindings, we map both www.yourdomain.
com and yourdomain.com. Alternatively we setup a redirector
website to redirect traffic on yourdomain.com to www.yourdomain.
com. The later is better because this way users are never
browsing your website over yourdomain.com and they will always
be on www.yourdomain.com. If your website is such that users
copy and share links to pages frequently, you should go for such
redirection.
• From IIS Logging, turn on “Bytes Sent” and “Bytes Received” fields.
Change creating log files to hourly ,if you have heavy traffic. This
way each log file size will be within the manageable size and if
you have to parse the log files, it won’t take too long. Whenever
we have to diagnose slow pages, we first look into the IIS log
and ensure if a page is taking a long time to execute, and it is not
because of large “Bytes Sent”.
• Map 404 to a well defined error page from IIS > Website > Error
Pages > 404. You can set it to redirect to your websites homepage.
• Copy website code to each server and synchronize the files last
modification date and time. This way, each file will have the exact
same last modified date time on each server. That means, if a
browser gets jquery.js file from webserver1, and it tries to hit
webserver2 on another page visit and asks webserver2 about the
last modified datetime of jquery.js, it will get the exact same date
time and it won’t download the whole file again.
• Create a static website hosted on a different domain. Eg.
Staticyourdomain.com and have all static files served from this
domain. It prevents large ASP.NET cookies from being sent over
static files.
These are some techniques we have learnt over the years to avoid
common mistakes and tune websites to serve well cached traffic to
the browser, delivering faster page load performance.
05
Removing unwanted HTTP headers
There are some HTTP response headers that make hackers lives
easier in order to detect what version of IIS you are running on
and what .NET version you are on. You can remove most of these
headers using web.config. But there are some that cannot be
removed using the config file and you need to write a custom
HttpModule to remove those from every response; especially the
ETag header that IIS 7 has made it impossible to remove via any
configuration.
Removing ETag is one of the best ways to get better caching from
browser for the static files on your website. Here’s a HTTP Module
that can remove the headers that you don’t need:
public class RemoveASPNETStuff : IHttpModule
{
public void Init(HttpApplication app)
{
app.PostReleaseRequestState += app_
PostReleaseRequestState;
}
void app_PostReleaseRequestState(object sender, EventArgs
e)
{ var headers = HttpContext.Current.Response.Headers;
headers.Remove(“Server”);
headers.Remove(“X-AspNet-Version”);
headers.Remove(“ETag”);
}
Before the HttpModule:
Cache-Control:private
Content-Length:445
Content-Type:text/html; charset=utf-8
Date:Sun, 31 Mar 2013 11:19:36 GMT
Server:Microsoft-IIS/8.0
Vary:Accept-Encoding
X-AspNet-Version:4.0.30319
After the HttpModule:
Cache-Control:private
Content-Length:445
Content-Type:text/html; charset=utf-8
Date:Sun, 31 Mar 2013 11:16:03 GMT
Vary:Accept-Encoding
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