CURLOPT_SSL_SESSIONID_CACHE - use the SSL session-ID cache

Added in curl 7.16.0

1

Pass a long set to 0 to disable libcurl's use of SSL session-ID caching. Set this to 1 to enable it. By default all transfers are done using the cache enabled. While nothing ever should get hurt by attempting to reuse SSL session-IDs, there seem to be or have been broken SSL implementations in the wild that may require you to disable this in order for you to succeed.

int main(void) { CURL *curl = curl_easy_init(); if(curl) { CURLcode res; curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/"); /* switch off session-id use */ curl_easy_setopt(curl, CURLOPT_SSL_SESSIONID_CACHE, 0L); res = curl_easy_perform(curl); curl_easy_cleanup(curl); } }

CURLOPT_SSL_SESSIONID_CACHE - use the SSL session-ID cache

This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. All TLS backends support this option.

curl_easy_setopt(3) returns a CURLcode indicating success or error. CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3).

CURLOPT_DNS_CACHE_TIMEOUT(3), CURLOPT_MAXAGE_CONN(3), CURLOPT_MAXLIFETIME_CONN(3), CURLOPT_SSLVERSION(3) libcurl 2025-06-16 CURLOPT_SSL_SESSIONID_CACHE(3)

#include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_SESSIONID_CACHE, long enabled);