New web server notes for content providers and users

There is a new web server (dean.star.bnl.gov) online to replace ch2linux.star.bnl.gov.  The "online.star.bnl.gov" alias was switched to dean.star.bnl.gov at about 2pm on Tuesday, Feb. 29, 2007.  There is perhaps as much as 24 hours of DNS propagation time for the alias change to make it around the world, during which time, there could be confusion about which system (dean or ch2linux) is actually being accessed.

We plan to keep ch2linux online for 1-2 weeks to help in debugging, and as a fallback for broken content until it is fixed.

A gotcha to watch out for is the hard-coding of the "ch2linux" name in any links.  Use of the "online.star.bnl.gov" alias is generally preferable.

For those of you with individual accounts on ch2linux, the accounts have been duplicated on the new server (if you have an account, you can immediately use the key management system ( https://www.star.bnl.gov/starkeyw ) to install openssh public keys if desired on both the current (ch2linux) and new (dean) web servers).

Some hints and suggestions for content maintainers:

Some of the configuration changes between ch2linux and dean (particularly to php) may require modifcations to existing content to work properly on the new server.  With php, the change that seems most likely to bite us is "register_globals = Off".  On ch2linux, this is set to On, allowing php automatic access to variables passed in POST or GET requests.  Here is a quick primer on the effect of turning this off, taken from the php.ini file:

;     Global variables are no longer registered for input data (POST, GET, cookies,
;     environment and other server variables).  Instead of using $foo,
;     you can use $_REQUEST["foo"] (includes any variable that arrives through the
;     request, namely, POST, GET and cookie variables), or use one of the specific
;     $_GET["foo"], $_POST["foo"], $_COOKIE["foo"] or $_FILES["foo"], depending
;     on where the input originates.  Also, you can look at the
;     import_request_variables() function.
;     Note that register_globals is going to be depracated (i.e., turned off by
;     default) in the next version of PHP, because it often leads to security bugs.
;     Read http://php.net/manual/en/security.registerglobals.php for further
;     information.

A second php issue is that we'd like to keep the default setting of "display_errors = Off" in php, as a security precaution.  However, since having it turned on is often useful for debugging, we can leave it on for a week or two in the initial stages, then turn it back to off.  A common issue with these php settings, is that you might notice mostly harmless "Notice" messages from php - commonly about uninitialized variables -- we all know to always initialize our variables, right?

If your php code (or perl, or whatever) is encountering file access errors, the problem may be stemming from SELinux.  I have fixed several file contexts and the local SE policy to fix problems with the RICH Scaler plots, the RunLog Browser and tomcat.  Unfortunately, content owners may have a difficult time diagnosing such problems.  One way is to login to the server, "cause" the error and then look at the output of "dmesg |tail -n 30" (30, 40, whatever it takes) and look for an audit messeages with "avc:  denied" lines that might be related to your content.  If you see such errors, inform Wayne Betts who can look into it further.  As a quick test, we can temporarily disable SELinux to see if it clears up any problems.



Another common issue has been database access controls.  Many of our databases have fairly granular access controls, and dean may not be configured for access to everything it needs.  If that is the suspected source of any problems, Mike DePhillips can look into it.