A somewhat obscure xinetd error

I was playing around with check_mk and xinetd. I was getting a strange error from Running sudo xinetd -d -dontfork:

15/3/17@10:59:57: NOTICE: 20277 {main} Started working: 1 available service
15/3/17@10:59:57: DEBUG: 20277 {main_loop} active_services = 1
15/3/17@11:00:06: DEBUG: 20277 {main_loop} select returned 1
15/3/17@11:00:06: DEBUG: 20277 {server_start} Starting service check_mk
15/3/17@11:00:06: DEBUG: 20277 {main_loop} active_services = 1
15/3/17@11:00:06: DEBUG: 20277 {main_loop} active_services = 1
15/3/17@11:00:06: DEBUG: 20277 {main_loop} select returned 1
15/3/17@11:00:06: DEBUG: 20277 {check_pipe} Got signal 17 (Child exited)
15/3/17@11:00:06: DEBUG: 20277 {child_exit} waitpid returned = 20279
15/3/17@11:00:06: DEBUG: 20277 {server_end} check_mk server 20279 exited
15/3/17@11:00:06: INFO: 20277 {conn_free} freeing connection
15/3/17@11:00:06: DEBUG: 20277 {child_exit} waitpid returned = -1

Looking back up in the log showed

Service configuration: check_mk
    id = check_mk
    flags = IPv4
    type = UNLISTED
    socket_type = stream
    Protocol (name,number) = (tcp,6)
    port = 6556
    wait = no
    user = 0
    Groups = no
    PER_SOURCE = -1
    Bind = All addresses.
    Server = /usr/bin/check_mk_agent
    Server argv = check_mk_agent
    Only from: All sites
    No access: No blocked sites
    No logging

Hmm, this is weird as I had tried to set only_from. Trouble was, I set it using something like only_from = 10.10.10.10, 10.10.10.11, 10.10.10.12 No error message but no joy either. It choked on the commas; it needs to look like only_from = 10.10.10.10 10.10.10.11 10.10.10.12