Application control of TCP retransmission on Linux

Question

For the impatient:

How to change the value of /proc/sys/net/ipv4/tcp_retries2 for a single connection in Linux, using setsockopt()

Answer 1

After some thinking (and googling), I came to the conclusion that you can't change tcp_retries1 and tcp_retries2 value for a single socket unless you apply some sort of patch to the kernel. Is that feasible for you?

Otherways, you could use TCP_KEEPALIVE socket option whose purpose is to check if a connection is still active (it seems to me that that's exactly what you are trying to achieve, so it has sense). Pay attention to the fact that you need to tweak its default parameter a little, because the default is to disconnect after about 2 hrs!!!