SSL_CTX_SET_TIMEOUT(3) | Library Functions Manual | SSL_CTX_SET_TIMEOUT(3)

# NAME

`SSL_CTX_set_timeout`, `SSL_CTX_get_timeout` — manipulate timeout values for session caching

# SYNOPSIS

library “libssl” libcrypto
`#include <openssl/ssl.h>`

long
`SSL_CTX_set_timeout`(SSL_CTX *ctx, long t);

long
`SSL_CTX_get_timeout`(SSL_CTX *ctx);

# DESCRIPTION

`SSL_CTX_set_timeout`() sets the timeout for newly created sessions for ctx to t. The timeout value t must be given in seconds.

`SSL_CTX_get_timeout`() returns the currently set timeout value for ctx.

Whenever a new session is created, it is assigned a maximum lifetime. This lifetime is specified by storing the creation time of the session and the timeout value valid at this time. If the actual time is later than creation time plus timeout, the session is not reused.

Due to this realization, all sessions behave according to the timeout value valid at the time of the session negotiation. Changes of the timeout value do not affect already established sessions.

The expiration time of a single session can be modified using the SSL_SESSION_get_time(3) family of functions.

Expired sessions are removed from the internal session cache, whenever SSL_CTX_flush_sessions(3) is called, either directly by the application or automatically (see SSL_CTX_set_session_cache_mode(3)).

The default value for session timeout is decided on a per-protocol basis; see SSL_get_default_timeout(3). All currently supported protocols have the same default timeout value of 300 seconds.

# RETURN VALUES

`SSL_CTX_set_timeout`() returns the previously set timeout value.

`SSL_CTX_get_timeout`() returns the currently set timeout value.

# SEE ALSO

ssl(3), SSL_CTX_flush_sessions(3), SSL_CTX_set_session_cache_mode(3), SSL_get_default_timeout(3), SSL_SESSION_get_time(3)

# HISTORY

`SSL_CTX_set_timeout`() and `SSL_CTX_get_timeout`() first appeared in SSLeay 0.6.1 and have been available since OpenBSD 2.4.

June 8, 2025 | Debian