FreeBSD Manual Pages
LIBBLACKLIST(3) Library Functions Manual LIBBLACKLIST(3) NAME blacklist_open, blacklist_open2, blacklist_close, blacklist_r, blacklist, blacklist_sa, blacklist_sa_r -- Blacklistd notification li- brary 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 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 the necessary state to communi- cate with blacklistd(8) and returns a pointer to it, or NULL on fail- ure. The function blacklist_open2() is similar to blacklist_open() but al- lows a logger to be specified. If the logger is NULL, then no logging is performed. The blacklist_close() function frees all memory and resources used. The blacklist() function sends a message to blacklistd(8), with an in- teger action argument specifying the type of notification, a file de- scriptor 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 attempt. 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 in- valid. The blacklistd(8) daemon compares the username to a configured list of for- bidden usernames and blocks the address im- mediately if a forbidden username matches. (The BLACKLIST_BAD_USER support is not cur- rently 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 un- connected 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 owner- ship of the local endpoint using getsockname(2). 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. NOTES The library "libblacklist" has been renamed to libblocklist(3). SEE ALSO blacklistd.conf(5), blacklistd(8) AUTHORS Christos Zoulas FreeBSD 15.0 February 5, 2025 LIBBLACKLIST(3)
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | NOTES | SEE ALSO | AUTHORS
Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=libblacklist&sektion=3&manpath=FreeBSD+15.0-RELEASE+and+Ports>