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Cisco ASA 5500 Series Configuration Guide using ASDM
Chapter 70 Configuring Dynamic Access Policies
Guide to Creating DAP Logical Expressions using LUA
• Organizational Unit (OU) or other level of the hierarchy for the user object
• Group Name that follows a naming convention but has many possible matches—you might require
the ability to use a wildcard on group names.
You can accomplish this flexibility by creating a Lua logical expression in the Advanced section of the
DAP pane in ASDM.
OU-Based Match Example
DAP can use many attributes returned from an LDAP server in a logical expression. See the DAP trace
section for example output of this, or run a debug dap trace.
The LDAP server returns the user Distinguished Name (DN). This implicitly identifies where in the
directory the user object is located. For example, if the user DN is CN=Example
User,OU=Admins,dc=cisco,dc=com this user is located in OU=Admins,dc=cisco,dc=com. If all
administrators are in this OU (or any container below this level) you can use a logical expression to
match on this criteria as follows:
assert(function()
if ( (type(aaa.ldap.distinguishedName) == "string") and
(string.find(aaa.ldap.distinguishedName, "OU=Admins,dc=cisco,dc=com$") ~= nil) )
then
return true
end
return false
end)()
In this example, the string.find function allows for a regular expression. Use the $ at the end of the string
to anchor this string to the end of the distinguishedName field.
Group Membership Example
You can create a basic logical expression for pattern matching of AD group membership. Because users
can be members of multiple groups, DAP parses the response from the LDAP server into separate entries
in a table. You need an advanced function to accomplish the following:
• Compare the memberOf field as a string (in the event the user belongs to only one group).
• Iterate through each returned memberOf field if the returned data is of type "table".
The function we have written and tested for this purpose is shown below. In this example, if a user is a
member of any group ending with "-stu" they match this DAP.
assert(function()
local pattern = "-stu$"
local attribute = aaa.ldap.memberOf
if ((type(attribute) == "string") and
(string.find(attribute, pattern) ~= nil)) then
return true
elseif (type(attribute) == "table") then
local k, v
for k, v in pairs(attribute) do
if (string.find(v, pattern) ~= nil) then
return true
end
end
end
return false
end)()