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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 successful and failed remote connections so that blacklistd can block or release port access to prevent Denial of Service attacks. The function blacklist_open() creates a 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 action argument specifying 1 for a failed connection or 0 for a successful connection, a file descriptor fd specifying the accepted file descriptor connected to the client, and an optional message in the msg argument. The blacklist_r() function is more efficient because it keeps the blacklist state around. The blacklist_sa() and blacklist_sa_r() functions can be used with unconnected sockets, where getpeername(2) will not work, the server will pass the peer name in the message. All functions log errors to syslogd(8). RETURN VALUES The function bl_open() returns a cookie on success and NULL on failure setting errno to an appropriate value. The bl_send() function returns 0 on success and -1 on failure setting errno to an appropriate value. SEE ALSO blacklistd.conf(5), blacklistd(8) AUTHORS Christos Zoulas FreeBSD 14.1-RELEASE-p8 January 22, 2015 FreeBSD 14.1-RELEASE-p8