Re: [LARTC] Count no of hosts

["Martin A. Brown" <mabrown-lartc@securepipe.com>]

 : Is there any way to dynamically measure the no of concurrent internal
 : hosts (IP's) utilising the linux NAT Gateway/forwarding box.

If you have root level access to the box, you can use a bit of shell to
determine the number of concurrent "clients" in any given instant.  This
assumes, of course, that you don't have an internally SNATed/masqueraded
network which {c,w}ould hide more clients.

ipchains?

# /sbin/ipchains -MnL | awk '/[0-9][0-9]:[0-9][0-9]/{print $3}' \
>  | sort | uniq | wc -l

iptables?

# awk '/(ESTABLISHED|ASSURED)/{print $5}' /proc/net/ip_conntrack \
>  | sort | uniq

Naturally with iptables, you'll need to know a bit more about your use of
the connection tracking to disambiguate any inbound or internal to DMZ
connections to accurately count your SNAT/MASQUERADEd connections.

The above shell is not designed with efficiency in mind (obviously), but
you get the idea.

-Martin

-- 
Martin A. Brown --- SecurePipe, Inc. --- mabrown@securepipe.com

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