LIBBLACKLIST(3)

LIBBLACKLIST(3) | 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 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 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

January 22, 2015 | NetBSD 8.0