Initial documentation

[hcoop/debian/libapache-mod-waklog.git] / README

INTRO

mod_waklog is an Apache module that provides aklog-like semantics
for the web.  mod_waklog will acquire (and store in the kernel) an
AFS credential when a connection is opened, use the credential for
the duration of the connection, and will remove the credential when
the connection is closed.

mod_waklog allows you to permit directories using AFS ACLs, and access
them via a web browser.  An ACL of "umweb:servers rl" is required for
each mod_waklog-protected directory.

mod_waklog allows scripts to run as you.  Programs which use AFS
credentials to authenticate themselves do so as you.

mod_waklog often is used with mod_cosign, and uses the cosign-provided
krbtgt to acquire an AFS credential; this extends single signon to AFS
via the web.

PHASES

Apache processes a request in multiple phases.

mod_waklog runs at phase 0 to acquire credentials via a keytab, and
runs at phase 2 to remove the credentials.

mod_waklog runs at phase 7 to acquire credentials of whatever krbtgt
is referenced via KRB5CCNAME (e.g., set by mod_cosign).

mod_waklog runs at connection termination to remove the credentials
it acquired at phase 0 or phase 7.

Apache calls stat() between phase 1 and phase 2 to determine if it
has access to the directory; if it doesn't have read access at that
point, it won't try to read it again, even if later phases would
acquire credentials which would allow it to do so.  mod_waklog
acquires an afs credential for a principal in the pts group
umweb:servers at phase 0, and removes this credential at phase 2;
directories permitted "umweb:servers rl" will allow the stat() call
to succeed.