Greetings all,

1) I have recently enabled NTOP as our Netflow collector and reporter. I have enabled 
Netflow version 5 transmissions from our 3550 cisco routers to the Redhat 9 host 
running the NTOP software. There are 6 x 3550 ciscos distributed between our 3 
buildings with fibre campus links between them all. Each 3550 hosts and/or peers the 
trunks and Vlans accessible on our network. Each VLAN has netflow "ip route-cache 
flow" enabled adn each 3550 has its netflows directed to the NTOP box.

Netflow config example:
 ip flow-export source Vlan20
 ip flow-export version 5 origin-as
 ip flow-export destination 172.21.254.100 2055

Now the problem is that although NTOP is recording data sent by the 3550 
switches/routers there is traffic not appearing that would expect to see. For example 
oracle/unix dbase connections, Outlook -->Exchange traffic and web traffic from our 
ISA proxy server (proxy port = 80) is not recording, even though the data must 
traverse the same devices which are only reporting a small range of protocols (ie 
SNMP, ICMP, DNS, Telnet, NBios-IP, DHCP-BOOTP, etc do appear in the reports.

My questions are:

- Have I made a common config mistake?, or
- Am I expecting too much from Netflow 5?, or
- Am I confused about how netflow works?, or
- Are my public servant users just not doing anything at all? (even the slackest 
employees checks out the web daily)

- Do I need to set the netflow timeouts on the routers to something other than default?

My understanding is that netflow is transmitted on closure of the connections, so does 
this mean days must pass to see the traffic im missing?

-------------------

2) Heres an easier one hopefully:

In the ntop.conf file there is the setting for local networks

 --local-subnets 172.0.0.0/32

- My question is how do I configure multiple local networks?

I have about 5 or 6 I would like recognised as local


3) Another config question

In the Netflow Plugin config:

- What is the virtual netflow interface and what relevance does the Ip and mask have 
to the way reports are displayed?



Cheers in advance

Sean Dunlop
Network & Security Consultant
Department of Treasury & Finance 
200 St Georges Tce 
Perth WA 6000 
Phone - (08) 9262 1405 
Fax - (08) 9262 1496 
Email - [EMAIL PROTECTED] 
Web - www.dtf.wa.gov.au 



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