Attempts to enumerate valid usernames on web servers running with the mod_userdir module or similar enabled. The Apache mod_userdir module allows user-specific directories to be accessed using the http://example.com/~user/ syntax. This script makes http requests in order to discover valid user- specific directories and infer valid usernames. By default, the script will use Nmap's 'nselib/data/usernames.lst'. An HTTP response status of 200 or 403 means the username is likely a valid one and the username will be output in the script results along with the status code (in parentheses). This script makes an attempt to avoid false positives by requesting a directory which is unlikely to exist. If the server responds with 200 or 403 then the script will not continue testing it. CVE-2001-1013: http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2001-1013. SYNTAX: userdir.users: The filename of a username list. http.useragent: The value of the User-Agent header field sent with requests. By default it is ''Mozilla/5.0 (compatible Nmap Scripting Engine http://nmap.org/book/nse.html)''. A value of the empty string disables sending the User-Agent header field. limit: The maximum number of users to check. http-max-cache-size: The maximum memory size (in bytes) of the cache. http.pipeline: If set, it represents the number of HTTP requests that'll be pipelined (ie, sent in a single request). This can be set low to make debugging easier, or it can be set high to test how a server reacts (its chosen max is ignored).