Network monitoring

teeno · 08-28-2001, 09:50 AM

Hi All,

Is there any software that will monitor network activity? I want to be able to see who has open telnet sessions though my Linux firewall and also the bandwidth being used.

neil · 08-29-2001, 05:23 AM

# netstat -peat
Should do this for you.
The -p gives you the process ID, very useful.

teeno · 08-29-2001, 06:01 AM

That's useful but it doesn't show open telnet sessions.

The Linux box is being used as a gateway. All the windows users on the network connect though the Linux box to access our AS400 server in the US. From time to time I need to reboot the Linux box and it would be nice if I could see if anyone on the network is connected before I shutdown the server. I would also need the IP address of the computers connected so that I can inform the user that they will be disconnected.

Is this possible?

Thank you

neil · 08-29-2001, 06:41 AM

Have you tried it?

It doesnt show you bandwidth but it certainly shows ip addresses and open (ESTABLISHED) connections. It also shows whch ports connections are on.

You can use the netstat command to see Tx and RX data as well,
you should beable to work out the traffic over time to obtain bandwidth.
Regards.

neil · 08-29-2001, 06:46 AM

PS netstat -t and netstat -s used with a sed and awk script over time will beable to calculate everything you need to know.

teeno · 08-29-2001, 07:14 AM

Your right netstat does show all the information I need.

I used netstat -M to show all the masquerade connections.

Thank you.

coopergr · 08-29-2001, 01:26 PM

Hi,

Check out www.mrtg.org - this is an excellent utility for monitoring bandwidth on an SNMP enabled device.

I am using it on Cisco 7204, 2924, & 6509's, but you can also run it from other devices once it is installed.

It is a PERL based utility, I am using it on WIN2K and publishing the bandwidth graphs to IIS 5.0, but you can run it on Linux and publish it on Apache no problem.

L8r