Re: Doubts about listen backlog and tcp_max_syn_backlog

+    { "ListenDrops", N_("%u SYNs to LISTEN sockets dropped"), opt_number },

(see the file debian/patches/CVS-20081003-statistics.c_sync.patch
 in the net-tools src)

i.e., the netstat pkg is printing the value of the TCPEXT MIB counter
that's counting TCPExtListenDrops.

Theoretically, that number should be the same as that printed by nstat,
as they are getting it from the same kernel stats counter. I have not
looked at nstat code (I actually almost always dump the counters from
/proc/net/{netstat + snmp} via a simple prettyprint script (will send
you that offline).

nstat pretty much does what you describe which is to parse the
/proc/net files(s) and
print the contents. This is one advantage of nstat over netstat. When
you add a new MIB, you
do not need to update nstat.

If the nstat and netstat counters don't match, something is fishy.
That nstat output is broken.