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LIBBLACKLIST(3) Library Functions Manual LIBBLACKLIST(3) NAME blacklist_open, blacklist_open2, blacklist_close, blacklist_r, blacklist, blacklist_sa, blacklist_sa_r -- Blacklistd notification library LIBRARY libblacklist SYNOPSIS #include <blacklist.h> struct blacklist * blacklist_open(void); struct blacklist * blacklist_open2(void (*logger)(int, struct syslog_data *, va_list)); 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 function blacklist_open2() is similar to blacklist_open() but allows a logger to be specified. If the logger is NULL, then no logging is per- formed. The blacklist_close() function frees all memory and resources used. The blacklist() function sends a message to blacklistd(8), with an integer action argument specifying the type of notification, a file descriptor fd specifying the accepted file descriptor connected to the client, and an op- tional 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 behav- ior from the remote system. The remote address should be blocked as soon as possible. BLACKLIST_BAD_USER The sending daemon has determined the username presented for authentication is invalid. The blacklistd(8) daemon compares the username to a configured list of forbidden usernames and blocks the address immediately if a forbidden username matches. (The BLACKLIST_BAD_USER sup- port is not currently available.) 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 uncon- nected sockets, where getpeername(2) will not work, the server will pass the peer name in the message. In all cases the file descriptor passed in the fd argument must be pointing to a valid socket so that blacklistd(8) can establish ownership of the lo- cal endpoint using getsockname(2). By default, syslogd(8) is used for message logging. The internal bl_cre- ate() function can be used to create the required internal state and spec- ify a custom logging function. RETURN VALUES The function blacklist_open() returns a cookie on success and NULL on fail- ure 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. NOTES The libblacklist has been renamed to libblocklist(3). SEE ALSO blacklistd.conf(5), blacklistd(8) AUTHORS Christos Zoulas FreeBSD ports 15.1 February 5, 2025 LIBBLACKLIST(3)
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | NOTES | SEE ALSO | AUTHORS
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