how I will use setsockopt and getsockopt with KEEP_ALIVE in linux c programming to determine broken tcp/ip connection?

c, linux, tcp

Solution

From the TCP man page:

To set or get a TCP socket option, call `getsockopt(2)` to read or `setsockopt(2)` to write the option with the option level argument set to `IPPROTO_TCP`.

Here are the relevant options:

`TCP_KEEPCNT` (since Linux 2.4)

The maximum number of keepalive probes TCP should send before dropping the connection. This option should not be used in code intended to be portable.

`TCP_KEEPIDLE` (since Linux 2.4)

The time (in seconds) the connection needs to remain idle before TCP starts sending keepalive probes, if the socket option SO_KEEPALIVE has been set on this socket. This option should not be used in code intended to be portable.

`TCP_KEEPINTVL` (since Linux 2.4)

The time (in seconds) between individual keepalive probes. This option should not be used in code intended to be portable.

Example:

int keepcnt = 5;
int keepidle = 30;
int keepintvl = 120;

setsockopt(sock, IPPROTO_TCP, TCP_KEEPCNT, &keepcnt, sizeof(int));
setsockopt(sock, IPPROTO_TCP, TCP_KEEPIDLE, &keepidle, sizeof(int));
setsockopt(sock, IPPROTO_TCP, TCP_KEEPINTVL, &keepintvl, sizeof(int));

Problem

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