Introduction to Library Functions                 HOSTSACES(3)



NAME
     hostsaccess, hostsctl, requestinit, requestset -  access
     control library

SYNOPSIS
     #include 

     cc [ flag  ... ] file ...  [ library ... ] -lwrap

     extern int allowseverity;
     extern int denyseverity;

     struct requestinfo *requestinit(request, key, value, ..., 0)
     struct requestinfo *request;

     struct requestinfo *requestset(request, key, value, ..., 0)
     struct requestinfo *request;

     int hostsaccess(request)
     struct requestinfo *request;

     int hostsctl(daemon, clientname, clientaddr, clientuser)
     char *daemon;
     char *clientname;
     char *clientaddr;
     char *clientuser;

DESCRIPTION
     The routines described in this  document  are  part  of  the
     libwrap.so  library. They implement a rule-based access con-
     trol language with optional shell commands that are executed
     when a rule fires.

     requestinit()  initializes  a  structure  with  information
     about  a  client  request.  requestset() updates an already
     initialized  request  structure.  Both  functions   take   a
     variable-length  list  of  key-value  pairs and return their
     first argument.  The argument lists are  terminated  with  a
     zero  key value. All string-valued arguments are copied. The
     expected keys (and corresponding value types) are:

     RQFILE (int)
          The file descriptor associated with the request.

     RQCLIENTNAME (char *)
          The client host name.

     RQCLIENTADR (char *)
          A  printable  representation  of  the  client   network
          address.

     RQCLIENTSIN (struct sockaddrin *)



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Introduction to Library Functions                 HOSTSACES(3)



          An  internal  representation  of  the  client   network
          address  and  port.   The contents of the structure are
          not copied.

     RQSERVERNAME (char *)
          The  hostname  associated  with  the  server   endpoint
          address.

     RQSERVERADR (char *)
          A  printable  representation  of  the  server  endpoint
          address.

     RQSERVERSIN (struct sockaddrin *)
          An  internal  representation  of  the  server  endpoint
          address  and  port.   The contents of the structure are
          not copied.

     RQDAEMON (char *)
          The name of the daemon process running  on  the  server
          host.

     RQUSER (char *)
          The name of the user on whose behalf  the  client  host
          makes the request.

     hostsaccess() consults the access control tables  described
     in  the hostsaccess(4) manual page.  When internal endpoint
     information is available, host names and client  user  names
     are  looked  up  on demand, using the request structure as a
     cache.  hostsaccess() returns  zero  if  access  should  be
     denied.

     hostsctl() is  a  wrapper  around  the  requestinit()  and
     hostsaccess()  routines  with  a  perhaps  more  convenient
     interface (though it does not pass on enough information  to
     support automated client username lookups).  The client host
     address, client host name and username arguments should con-
     tain valid data or STRINGUNKNOWN.  hostsctl() returns zero
     if access should be denied.

     The allowseverity and denyseverity variables determine how
     accepted  and  rejected requests may be logged. They must be
     provided by the caller and may be modified by rules  in  the
     access control tables.

DIAGNOSTICS
     Problems are reported via the syslog daemon.

SEE ALSO
     hostsaccess(4),  format  of  the  access  control   tables.
     hostsoptions(4), optional extensions to the base language.




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Introduction to Library Functions                 HOSTSACES(3)



FILES
     /etc/hosts.allow, /etc/hosts.deny, access control tables.

BUGS
     hostsaccess() uses the strtok() library function. This  may
     interfere with other code that relies on strtok().

AUTHOR
     Wietse Venema (wietse@wzv.win.tue.nl)
     Department of Mathematics and Computing Science
     Eindhoven University of Technology
     Den Dolech 2, P.O. Box 513,
     5600 MB Eindhoven, The Netherlands


ATRIBUTES
     See attributes(5) for descriptions of the following attri-
     butes:

     
       ATRIBUTE TYPE     ATRIBUTE VALUE
    
     Availability         SUNWtcpd       
    
     Interface Stability  Committed      
    

NOTES
     Source for tcpwrappers is available in the SUNWtcpdS pack-
     age.

























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