Hello,
I have not used mbuffer for a long time, so won't comment on that.
But your netstat call looks unsuitable to diagnose.
I'd propose to use
ss -f inet -lpn
ss instead of netstat... I try to catch up with changing times :-)
-f inet because in this case, you're (probably) just interested in IPv4
network sockets. Could be IPv6, of course, then use inet6
-l list listening sockets, not active connections
-p show the process using the socket. Will usually require root
-n show numbers, not translated names
l and n are probably most important for you (and are also available for
netstat) as you would otherwise first miss a listening socket, and then
have grep miss the output if you use a port number that is assigned (see
/etc/services)
Good luck!
Arno
--
Arno Lehmann
IT-Service Lehmann
Sandstr. 6, 49080 Osnabrück