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)