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LIBBLACKLIST(3)	       FreeBSD Library Functions Manual	       LIBBLACKLIST(3)

NAME
     blacklist_open, blacklist_close, blacklist_r, blacklist, blacklist_sa,
     blacklist_sa_r -- Blacklistd notification library

LIBRARY
     library "libblacklist"

SYNOPSIS
     #include <blacklist.h>

     struct blacklist *
     blacklist_open(void);

     void
     blacklist_close(struct blacklist *cookie);

     int
     blacklist(int action, int fd, const char *msg);

     int
     blacklist_r(struct	blacklist *cookie, int action, int fd,
	 const char *msg);

     int
     blacklist_sa(int action, int fd, const struct sockaddr *sa,
	 socklen_t salen, const	char *msg);

     int
     blacklist_sa_r(struct blacklist *cookie, int action, int fd,
	 const struct sockaddr *sa, socklen_t salen, const char	*msg);

DESCRIPTION
     These functions can be used by daemons to notify blacklistd(8) about suc-
     cessful and failed	remote connections so that blacklistd can block	or re-
     lease port	access to prevent Denial of Service attacks.

     The function blacklist_open() creates the necessary state to communicate
     with blacklistd(8)	and returns a pointer to it, or	NULL on	failure.

     The blacklist_close() function frees all memory and resources used.

     The blacklist() function sends a message to blacklistd(8),	with an	inte-
     ger action	argument specifying the	type of	notification, a	file descrip-
     tor fd specifying the accepted file descriptor connected to the client,
     and an optional message in	the msg	argument.

     The action	parameter can take these values:

     BLACKLIST_AUTH_FAIL	 There was an unsuccessful authentication at-
				 tempt.

     BLACKLIST_AUTH_OK		 A user	successfully authenticated.

     BLACKLIST_ABUSIVE_BEHAVIOR	 The sending daemon has	detected abusive be-
				 havior	from the remote	system.	 The remote
				 address should	be blocked as soon as possi-
				 ble.

     BLACKLIST_BAD_USER		 The sending daemon has	determined the user-
				 name presented	for authentication is invalid.
				 The blacklistd(8) daemon compares the user-
				 name to a configured list of forbidden	user-
				 names and blocks the address immediately if a
				 forbidden username matches.  (The
				 BLACKLIST_BAD_USER support is not currently
				 available.)

     The blacklist_r() function	is more	efficient because it keeps the black-
     list state	around.

     The blacklist_sa()	and blacklist_sa_r() functions can be used with	uncon-
     nected sockets, where getpeername(2) will not work, the server will pass
     the peer name in the message.

     By	default, syslogd(8) is used for	message	logging.  The internal
     bl_create() function can be used to create	the required internal state
     and specify a custom logging function.

RETURN VALUES
     The function blacklist_open() returns a cookie on success and NULL	on
     failure setting errno to an appropriate value.

     The functions blacklist(),	blacklist_sa(),	and blacklist_sa_r() return 0
     on	success	and -1 on failure setting errno	to an appropriate value.

SEE ALSO
     blacklistd.conf(5), blacklistd(8)

AUTHORS
     Christos Zoulas

FreeBSD	13.0			  May 5, 2017			  FreeBSD 13.0
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | SEE ALSO | AUTHORS

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