Read the entries in docs/FAQ and the back traffic on this.

Check the values in the info.html report (I probably should add a few counts
count for various cases - it might be that the ntop generated queries are
failing).

Read through resolveAddress() in address.c - ntop does everything possible
to avoid making a dns query.

Note that the address resolution thread uses resolveAddress(&addr, 0, 0 /*
use default device */);, i.e. the 1st device in the list from Admin | switch
NIC

Whereas the call in getHostInfo() and the one when allocating a new host are
resolveAddress(&hostIpAddress, 0, actualDeviceId); (i.e. the current
reporting device).

So, if you don't have DNS resolution on all your interfaces, the only way
it's resolving is via the sniff - which can take time.

(Suppose you have a 10. and a public IP and your DNS resolver is set to an
internal, 10. host, then queries out the public port will not succeed!)


-----Burton

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Chris
Bshaw
Sent: Friday, February 21, 2003 6:36 AM
To: [EMAIL PROTECTED]
Subject: [Ntop] DNS resolution and netflow


Hi....

I am using ntop 2.1.57 (from sourceforge) on RedHat 7.3 as a netflow
collector.

It all seems to work OK, but on the webinterface, all I get it IP
addresses....eg: if I go to Total -> TCP/UDP, I get a long table of hosts
with traffic stats, but the 'Host' column only has IP addresses.....

I have noticed that if I use the Admin -> Switch NIC to switch to eth0
(which disables netflow collection), the 'Host' column DOES have actual
names rather than IP addresses.....

I am running ntop with the @<configfile> option.....the contents of my
config file are below.....

-u ntop
-P /usr/share/ntop/ntop-backbone
-D <local domain>
-m <list of local subnets>
-M
-E
-C
-p /etc/protocols.ntop
-w 3000

....also it appears that the DNS address resolution thread is starting:

21/Feb/2003 12:29:43 Started thread (3076) for DNS address resolution.
21/Feb/2003 12:29:43 Initializing plugins (if any)...
21/Feb/2003 12:29:43 Starting plugin 'rrdPlugin'...
21/Feb/2003 12:29:43 Welcome to the RRD plugin...
21/Feb/2003 12:29:43 THREADMGMT: Address resolution thread started...

....and the files addressCache.db and dnsCache.db exist where they are
supposed to be and they are getting updated, and do contain valid names (I
looked using the 'strings' command).

Am I doing something wrong?

Or is IP -> name resolution disabled when using the NetFlow-Device?

Thanx in advance.

Chris.



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