NAME

       CURLOPT_TCP_KEEPALIVE - TCP keep-alive probing

SYNOPSIS

       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_TCP_KEEPALIVE, long probe);

DESCRIPTION

       Pass  a long. If set to 1, TCP keepalive probes are used. The delay and frequency of these
       probes can be controlled by  the  CURLOPT_TCP_KEEPIDLE(3),  CURLOPT_TCP_KEEPINTVL(3),  and
       CURLOPT_TCP_KEEPCNT(3)  options,  provided  the  operating  system supports them. Set to 0
       (default behavior) to disable keepalive probes.

DEFAULT

       0

PROTOCOLS

       This functionality affects tcp only

EXAMPLE

       int main(void)
       {
         CURL *curl = curl_easy_init();
         if(curl) {
           curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

           /* enable TCP keep-alive for this transfer */
           curl_easy_setopt(curl, CURLOPT_TCP_KEEPALIVE, 1L);

           /* keep-alive idle time to 120 seconds */
           curl_easy_setopt(curl, CURLOPT_TCP_KEEPIDLE, 120L);

           /* interval time between keep-alive probes: 60 seconds */
           curl_easy_setopt(curl, CURLOPT_TCP_KEEPINTVL, 60L);

           /* maximum number of keep-alive probes: 3 */
           curl_easy_setopt(curl, CURLOPT_TCP_KEEPCNT, 3L);

           curl_easy_perform(curl);
         }
       }

AVAILABILITY

       Added in curl 7.25.0

RETURN VALUE

       Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.

SEE ALSO

       CURLOPT_LOW_SPEED_LIMIT(3),    CURLOPT_MAX_RECV_SPEED_LARGE(3),    CURLOPT_TCP_KEEPCNT(3),
       CURLOPT_TCP_KEEPIDLE(3), CURLOPT_TCP_KEEPINTVL(3)