Linux TCP Keepalive – Is It Application Dependent?

Your assessment of the TCP keepalive functionality in Windows being like Linux is correct.

You can manipulate the registry parameters related to TCP keepalives all you want, but unless the application uses setsockopt() to request keepalives none will be sent by default.

If you want to actually see keepalives in action on Windows and don't want to write code, tick the "Enable TCP keepalives (SO_KEEPALIVE)" in the "Connection" properties in the PuTTY SSH/TELNET/etc client, initiate a connection, allow it to sit idle, and sniff the traffic. (It's the first app I could think of that I knew could be consciouly configured to use SO_KEEPALIVE...)

You can do it by using this simple one way command, which uses the /proc/modules and /sys virtual filesystems:

cat /proc/modules | cut -f 1 -d " " | while read module; do \
 echo "Module: $module"; \
 if [ -d "/sys/module/$module/parameters" ]; then \
  ls /sys/module/$module/parameters/ | while read parameter; do \
   echo -n "Parameter: $parameter --> "; \
   cat /sys/module/$module/parameters/$parameter; \
  done; \
 fi; \
 echo; \
done

You will obtain an output like this:

...
...
Module: vboxnetadp

Module: vboxnetflt

Module: vboxdrv
Parameter: force_async_tsc --> 0

Module: binfmt_misc

Module: uinput

Module: fuse
Parameter: max_user_bgreq --> 2047
Parameter: max_user_congthresh --> 2047

Module: md_mod
Parameter: new_array --> cat: /sys/module/md_mod/parameters/new_array: Permission denied
Parameter: start_dirty_degraded --> 0
Parameter: start_ro --> 0

Module: loop
Parameter: max_loop --> 0
Parameter: max_part --> 0

Module: kvm_intel
Parameter: emulate_invalid_guest_state --> N
Parameter: ept --> Y
Parameter: fasteoi --> Y
Parameter: flexpriority --> Y
Parameter: nested --> N
Parameter: ple_gap --> 0
Parameter: ple_window --> 4096
Parameter: unrestricted_guest --> Y
Parameter: vmm_exclusive --> Y
Parameter: vpid --> Y
Parameter: yield_on_hlt --> Y

Module: kvm
Parameter: allow_unsafe_assigned_interrupts --> N
Parameter: ignore_msrs --> N
Parameter: min_timer_period_us --> 500

Module: tpm_infineon

Module: joydev

Module: snd_hda_codec_hdmi
Parameter: static_hdmi_pcm --> N
...
...

Hope this helps.