1---
2c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
3SPDX-License-Identifier: curl
4Title: CURLOPT_TCP_KEEPALIVE
5Section: 3
6Source: libcurl
7See-also:
8  - CURLOPT_LOW_SPEED_LIMIT (3)
9  - CURLOPT_MAX_RECV_SPEED_LARGE (3)
10  - CURLOPT_TCP_KEEPIDLE (3)
11  - CURLOPT_TCP_KEEPINTVL (3)
12  - CURLOPT_TCP_KEEPCNT (3)
13Protocol:
14  - TCP
15Added-in: 7.25.0
16---
17
18# NAME
19
20CURLOPT_TCP_KEEPALIVE - TCP keep-alive probing
21
22# SYNOPSIS
23
24~~~c
25#include <curl/curl.h>
26
27CURLcode curl_easy_setopt(CURL *handle, CURLOPT_TCP_KEEPALIVE, long probe);
28~~~
29
30# DESCRIPTION
31
32Pass a long. If set to 1, TCP keepalive probes are used. The delay and
33frequency of these probes can be controlled by the
34CURLOPT_TCP_KEEPIDLE(3), CURLOPT_TCP_KEEPINTVL(3), and CURLOPT_TCP_KEEPCNT(3)
35options, provided the operating system supports them. Set to 0 (default behavior)
36to disable keepalive probes.
37
38# DEFAULT
39
400
41
42# %PROTOCOLS%
43
44# EXAMPLE
45
46~~~c
47int main(void)
48{
49  CURL *curl = curl_easy_init();
50  if(curl) {
51    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
52
53    /* enable TCP keep-alive for this transfer */
54    curl_easy_setopt(curl, CURLOPT_TCP_KEEPALIVE, 1L);
55
56    /* keep-alive idle time to 120 seconds */
57    curl_easy_setopt(curl, CURLOPT_TCP_KEEPIDLE, 120L);
58
59    /* interval time between keep-alive probes: 60 seconds */
60    curl_easy_setopt(curl, CURLOPT_TCP_KEEPINTVL, 60L);
61
62    /* maximum number of keep-alive probes: 3 */
63    curl_easy_setopt(curl, CURLOPT_TCP_KEEPCNT, 3L);
64
65    curl_easy_perform(curl);
66  }
67}
68~~~
69
70# %AVAILABILITY%
71
72# RETURN VALUE
73
74Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
75