Session Cookie not accessible across Sub-Domains

[Guest]

An ASP.NET session cookie set on "www.mydomain.com" can not be accessed on
"search.mydomain.com"; hence, a new session and cookie are being created on
every sub-domain.

This is occuring because ASP.NET always sets the Session cookie domain to
the full domain (e.g. "www.mydomain.com") instead of the parent domain (e.g.
"mydomain.com")

The problem with this is when the visitor goes to a different sub-domain
(e.g. "search.mydomain.com"), this sub-domain can not access the previously
set Session cookie, and hence, has no idea a session has already been
created. Hence, a new session is created with a new cookie set to
"search.mydomain.com". Now the visitor has two session cookies pointing to
two different sub-domains.

For the past couple of years, I've gotten around this by manually creating a
"ASP.NET_SessionId" cookie pointing to the parent domain (e.g.
"mydomain.com"). That way, all sub-domains have access to the same cookie and
the same session ID. However, this is a hack; I end up with multiple session
cookies pointing to "www.mydomain", "search.mydomain.com", and
"mydomain.com"; not the best solution.

How can I tell ASP.NET to always set the Session cookie domain to
"mydomain.com" so all sub-domains can read it? My research over the past
couple of years tells me this is impossible. This seems to be a major bug
that many people experience, however, I've heard no word of a fix nor any
comment on it from Microsoft.

Doug

 

[John Timney \(ASP.NET MVP\)]

When initially setting the cookie

Response.Cookies("domain").Value = DateTime.Now.ToString
Response.Cookies("domain").Expires = DateTime.Now.AddDays(1)
Response.Cookies("domain").Domain = "mydomain.com"

.................should do the trick.

I think its case sensitive at the browser.

--
Regards

John Timney
ASP.NET MVP
Microsoft Regional Director

 

[Guest]

Hi John,
Thank you for the reply. I'm not sure I understand; or perhaps vice-versa?

I don't set the ASP.NET Session cookie. ASP.NET does that all on it's own. I
do know how to write cookies and set domains, etc. My question is, how do I
get ASP.NET to set the correct domain wherever it set its own cookie?

Thanks,
Doug

 

[John Timney \(ASP.NET MVP\)]

sorry I misread your question (its late here!!).

You can't share sessions across domains, nor applications natively - so it
will always set a new cookie as you move between domains. Because you can
share cookies across those applications (and between those domains) one
approach is to store your shared data in a database and use a shared domain
cookie to identify the data in the database.

--
Regards

John Timney
ASP.NET MVP
Microsoft Regional Director

 

[Guest]

Hi John,
I wasn't referring to sharing sessions across parent domains (e.g.
"mydomain1.com" and "mydomain2.com"). I want to share sessions on sub-domains
of the same domain (e.g. "www.mydomain.com" and "search.mydomain.com").
Regards,
Doug

 

[John Timney \(ASP.NET MVP\)]

I expect the problem would be the same. Asp.net bounds sessions and objects
within applications for security, so if your subdomains were not part of the
same web application then the session would not apply. The solution could
be to have a root application, with all your other applications hanging
under it as non application virtual directories - and then have something
like the isapi virtual hosting filter handle the domains, allowing the root
application to own the single session. I've never tried it myself though.
I would always see a sub-domain as a seperate application entirely, or why
would it be a sub-domain?

--
Regards

John Timney
ASP.NET MVP
Microsoft Regional Director

 

[Guest]

Well, the out-of-proc StateServer works just fine for sharing sessions across
sub-domains. Everything in ASP.NET allows for sharing sessions across
sub-domains; everything except this simple cookie issue.

Let me explain one of the reasons why I need sessions to be shared across
sub-domains:
I have a "www" server, and a "search" server. When a person signs in, the
HTML header at the top of every page shows a link to "Sign Out". This same
header is used on every page throughout the site; on both "www" and "search".
Based on the session, I know whether the person is signed in or not, and
whether to show the "Sign Out" link or not. The session needs to persist
across sub-domains; otherwise, when a person goes to the "search" server,
they wouldn't appear to be signed in any longer.

There are many real-world examples of why sessions need to be shared across
sub-domains. e.g. Yahoo uses a single sign-on and you stay signed-in across
"mail.yessy.com", "shopping.yahoo.com", "music.yahoo.com", etc.

There are just so many examples of why a session would need to be shared
across sub-domains.

The ASP.NET StateServer natively supports sub-domains. The only issue is the
domain setting for the Session cookie. Instead of tying the cookie to
"www.mydomain.com", allow the cookie to be tied to "mydomain.com". That way,
all sub-domains can access the cookie and problem solved. People stay
signed-in across sub-domains; the same session can be accessed; etc.

Why not allow developers to share sessions across sub-domains if they need
to? It's an extremely simple feature to provide.

By the way, I implemented a fairly good fix/hack today. Put this code on
every page:
Response.Cookies["ASP.NET_SessionId"].Value = Session.SessionID;
Response.Cookies["ASP.NET_SessionId"].Domain = ".mydomain.com";

Those two lines of code rewrite the Session cookie so it's now accessible
across sub-domains.

My hope is that Microsoft will implement a web/machine.config param that
allows the Session cookie to be accessed across sub-domains.

Doug

 

[John Timney \(ASP.NET MVP\)]

good hack - I'll remember that one

--
Regards

John Timney
ASP.NET MVP
Microsoft Regional Director

Well, the out-of-proc StateServer works just fine for sharing sessions
across
sub-domains. Everything in ASP.NET allows for sharing sessions across
sub-domains; everything except this simple cookie issue.

Let me explain one of the reasons why I need sessions to be shared across
sub-domains:
I have a "www" server, and a "search" server. When a person signs in, the
HTML header at the top of every page shows a link to "Sign Out". This same
header is used on every page throughout the site; on both "www" and
"search".
Based on the session, I know whether the person is signed in or not, and
whether to show the "Sign Out" link or not. The session needs to persist
across sub-domains; otherwise, when a person goes to the "search" server,
they wouldn't appear to be signed in any longer.

There are many real-world examples of why sessions need to be shared
across
sub-domains. e.g. Yahoo uses a single sign-on and you stay signed-in
across
"mail.yessy.com", "shopping.yahoo.com", "music.yahoo.com", etc.

There are just so many examples of why a session would need to be shared
across sub-domains.

The ASP.NET StateServer natively supports sub-domains. The only issue is
the
domain setting for the Session cookie. Instead of tying the cookie to
"www.mydomain.com", allow the cookie to be tied to "mydomain.com". That
way,
all sub-domains can access the cookie and problem solved. People stay
signed-in across sub-domains; the same session can be accessed; etc.

Why not allow developers to share sessions across sub-domains if they need
to? It's an extremely simple feature to provide.

By the way, I implemented a fairly good fix/hack today. Put this code on
every page:
Response.Cookies["ASP.NET_SessionId"].Value = Session.SessionID;
Response.Cookies["ASP.NET_SessionId"].Domain = ".mydomain.com";

Those two lines of code rewrite the Session cookie so it's now accessible
across sub-domains.

My hope is that Microsoft will implement a web/machine.config param that
allows the Session cookie to be accessed across sub-domains.

Doug

I expect the problem would be the same. Asp.net bounds sessions and
objects
within applications for security, so if your subdomains were not part of
the
same web application then the session would not apply. The solution
could
be to have a root application, with all your other applications hanging
under it as non application virtual directories - and then have something
like the isapi virtual hosting filter handle the domains, allowing the
root
application to own the single session. I've never tried it myself
though.
I would always see a sub-domain as a seperate application entirely, or
why
would it be a sub-domain?

--
Regards

John Timney
ASP.NET MVP
Microsoft Regional Director