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Sun Java System Web Server 6.1 SP9 Administrator's Guide

Authorization Statements

Each ACL entry can include one or more authorization statements. Authorization statements specify who is allowed or denied access to a server resource. Use the following syntax when writing authorization statements:

allow|deny [absolute] (right[,right...]) attribute expression;

Start each line with either allow or deny. It’s usually a good idea to deny access to everyone in the first rule and then specifically allow access for users, groups, or computers in subsequent rules. This is because of the hierarchy of rules. That is, if you allow anyone access to a directory called /my_stuff, and then you have a subdirectory /my_stuff/personal that allows access to a few users, the access control on the subdirectory won’t work because anyone allowed access to the /my_stuff directory will also be allowed access to the /my_stuff/personal directory. To prevent this, create a rule for the subdirectory that first denies access to anyone and then allows it for the few users who need access.

However, in some cases if you set the default ACL to deny access to everyone, then your other ACL rules don’t need a “deny all” rule.

The following line denies access to everyone:

deny (all) user = "anyone";

This section includes the following topics:

Hierarchy of Authorization Statements

ACLs have a hierarchy that depends on the resource. For example, if the server receives a request for the document (URI) /my_stuff/web/presentation.html, the server builds a list of ACLs that apply for this URI. The server first adds ACLs listed in ”check-acl’ statements of it’s obj.conf file. Then the server appends matching URI and PATH ACLs.

The server processes this list in the same order. Unless ”absolute’ ACL statements are present, all statements are evaluated in order. If an ”absolute allow’ or ”absolute deny’ statement evaluates to ”true’, the server stops processing and accepts this result.

If there are more than one ACLs that match, the server uses the last statement that matches. However, if you use an absolute statement, then the server stops looking for other matches and uses the ACL containing the absolute statement. If you have two absolute statements for the same resource, the server uses the first one in the file and stops looking for other resources that match.

version 3.0;
acl "default";authenticate (user,group) {
     prompt="Web Server";
};
allow (read,execute,list,info)
     user = "anyone";allow (write,delete)
     user = "all";
acl "uri=/my_stuff/web/presentation.html";
deny (all)
     user = "anyone";
allow (all)
     user = "joe";

Attribute Expressions

Attribute expressions define who is allowed or denied access based on their username, group name, host name, or IP address. The following lines are examples of allowing access to different people or computers:

You can also restrict access to your server by time of day (based on the local time on the server) by using the timeofday attribute. For example, you can use the timeofday attribute to restrict access to certain users during specific hours.

Note –

Use 24-hour time to specify times. For example, use 0400 to specify 4:00 a.m. or 2230 for 10:30 p.m.

The following example restricts access to a group of users called guests between 8:00 a.m. and 4:59 p.m:

allow (read)

(group="guests") and (timeofday<0800 or timeofday=1700);

You can also restrict access by day of the week. Use the following three-letter abbreviations to specify days of the week: Sun, Mon, Tue, Wed, Thu, Fri, and Sat.

The following statement allows access for users in the premium group any day and any time. Users in the discount group get access all day on weekends and on weekdays anytime except 8am-4:59pm.

allow (read) (group="discount" and dayofweek="Sat,Sun") or (group="discount" and (dayofweek="mon,tue,wed,thu,fri" and(timeofday<0800 or timeofday=1700)))or (group="premium");

Operators For Expressions

You can use various operators in attribute expressions. Parentheses delineate the operator order of precedence. With user, group, dns, and ip, you can use the following operators:

With timeofday and dayofweek, you can use: