CURLOPT_TCP_KEEPALIVE(3) Library Functions Manual CURLOPT_TCP_KEEPALIVE(3)
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_KEEPI-
DLE(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
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).
SEE ALSO
CURLOPT_LOW_SPEED_LIMIT(3), CURLOPT_MAX_RECV_SPEED_LARGE(3), CUR-
LOPT_TCP_KEEPCNT(3), CURLOPT_TCP_KEEPIDLE(3), CURLOPT_TCP_KEEPINTVL(3)
libcurl 2026-07-12 CURLOPT_TCP_KEEPALIVE(3)
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