curl/docs/libcurl/opts/CURLOPT_TCP_KEEPALIVE.md

---

c: Copyright (C) Daniel Stenberg, daniel@haxx.se, et al. SPDX-License-Identifier: curl Title: CURLOPT_TCP_KEEPALIVE Section: 3 Source: libcurl See-also:

• CURLOPT_LOW_SPEED_LIMIT (3)
• CURLOPT_MAX_RECV_SPEED_LARGE (3)
• CURLOPT_TCP_KEEPIDLE (3)
• CURLOPT_TCP_KEEPINTVL (3)
• CURLOPT_TCP_KEEPCNT (3) Protocol:
• TCP Added-in: 7.25.0 ---

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%

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%

RETURN VALUE

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