1HOSTS_ACCESS(3) Library Functions Manual HOSTS_ACCESS(3)
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6 hosts_access, hosts_ctl, request_init, request_set - access control
7 library
8
10 #include "tcpd.h"
11 extern int allow_severity;
13 extern int deny_severity;
14 struct request_info *request_init(request, key, value, ..., 0)
16 struct request_info *request;
17 struct request_info *request_set(request, key, value, ..., 0)
19 struct request_info *request;
20 int hosts_access(request)
22 struct request_info *request;
23 int hosts_ctl(daemon, client_name, client_addr, client_user)
25 char *daemon;
26 char *client_name;
27 char *client_addr;
28 char *client_user;
29
31 The routines described in this document are part of the libwrap.a
32 library. They implement a rule-based access control language with
33 optional shell commands that are executed when a rule fires.
34 request_init() initializes a structure with information about a client
36 request. request_set() updates an already initialized request struc‐
37 ture. Both functions take a variable-length list of key-value pairs and
38 return their first argument. The argument lists are terminated with a
39 zero key value. All string-valued arguments are copied. The expected
40 keys (and corresponding value types) are:
41 RQ_FILE (int)
43 The file descriptor associated with the request.
44 RQ_CLIENT_NAME (char *)
46 The client host name.
47 RQ_CLIENT_ADDR (char *)
49 A printable representation of the client network address.
50 RQ_CLIENT_SIN (struct sockaddr_in *)
52 An internal representation of the client network address and
53 port. The contents of the structure are not copied.
54 RQ_SERVER_NAME (char *)
56 The hostname associated with the server endpoint address.
57 RQ_SERVER_ADDR (char *)
59 A printable representation of the server endpoint address.
60 RQ_SERVER_SIN (struct sockaddr_in *)
62 An internal representation of the server endpoint address and
63 port. The contents of the structure are not copied.
64 RQ_DAEMON (char *)
66 The name of the daemon process running on the server host.
67 RQ_USER (char *)
69 The name of the user on whose behalf the client host makes the
70 request.
71 hosts_access() consults the access control tables described in the
73 hosts_access(5) manual page. When internal endpoint information is
74 available, host names and client user names are looked up on demand,
75 using the request structure as a cache. hosts_access() returns zero if
76 access should be denied.
77 hosts_ctl() is a wrapper around the request_init() and hosts_access()
79 routines with a perhaps more convenient interface (though it does not
80 pass on enough information to support automated client username
81 lookups). The client host address, client host name and username argu‐
82 ments should contain valid data or STRING_UNKNOWN. hosts_ctl() returns
83 zero if access should be denied.
84 The allow_severity and deny_severity variables determine how accepted
86 and rejected requests may be logged. They must be provided by the call‐
87 er and may be modified by rules in the access control tables.
88
90 Problems are reported via the syslog daemon.
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93 hosts_access(5), format of the access control tables.
94 hosts_options(5), optional extensions to the base language.
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97 /etc/hosts.allow, /etc/hosts.deny, access control tables.
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100 hosts_access() uses the strtok() library function. This may interfere
101 with other code that relies on strtok().
102
104 Wietse Venema (wietse@wzv.win.tue.nl)
105 Department of Mathematics and Computing Science
106 Eindhoven University of Technology
107 Den Dolech 2, P.O. Box 513,
108 5600 MB Eindhoven, The Netherlands
109 HOSTS_ACCESS(3)