SSL_set_fd.3ssl - Man Page

connect the SSL object with a file descriptor


 #include <openssl/ssl.h>

 int SSL_set_fd(SSL *ssl, int fd);
 int SSL_set_rfd(SSL *ssl, int fd);
 int SSL_set_wfd(SSL *ssl, int fd);


SSL_set_fd() sets the file descriptor fd as the input/output facility for the TLS/SSL (encrypted) side of ssl. fd will typically be the socket file descriptor of a network connection.

When performing the operation, a socket BIO is automatically created to interface between the ssl and fd. The BIO and hence the SSL engine inherit the behaviour of fd. If fd is non-blocking, the ssl will also have non-blocking behaviour.

If there was already a BIO connected to ssl, BIO_free() will be called (for both the reading and writing side, if different).

SSL_set_rfd() and SSL_set_wfd() perform the respective action, but only for the read channel or the write channel, which can be set independently.

Return Values

The following return values can occur:


The operation failed. Check the error stack to find out why.


The operation succeeded.

See Also

SSL_get_fd(3), SSL_set_bio(3), SSL_connect(3), SSL_accept(3), SSL_shutdown(3), ssl(3) , bio(3)

Referenced By

ssl.3ssl(3), ssl.7ssl(7), SSL_get_fd.3ssl(3).

The man pages SSL_set_rfd.3ssl(3) and SSL_set_wfd.3ssl(3) are aliases of SSL_set_fd.3ssl(3).

2020-08-01 1.0.2o OpenSSL