man page of the nc command has following information

> -k      Forces nc to stay listening for another connection after its current connection is completed.  It
             is an error to use this option without the -l option.

But `nc --help` output has not any information regarding to -k option. 

And when I try to capture packages like 

> nc -kl -i 86400 -p 44444 > nc_44444.dmp 

I got following error 

> netcat: invalid option -- 'k'

So what is the problem ? Is there any option called as "-k" 

My problem is I have to capture some data from network and sometimes client application could disconnect from server port and it could reconnect again. So I don't want to get problem about disconnect/reconnect events