Question about interfaces on Linux machines

[Proxy]

What would be a good way, or command to use to see if a given interface (say eth0 for example) has something connected to the other end or is talking? I used <tcpdump -i eth0> but it still showed some traffic when I don't think there should have been. Line noise maybe?

 

[Bullitt]

tshark (CLI wireshark) and look at the output. Might be broadcast traffic from something on the same ethernet segment.

 

[Proxy]

Okay, outside of looking at MAC addresses, would there be anyway from the box itself to dertmine if there was anything sitting on the otherside? There is an interface that I think is unused but I don't want to bring it down and cause a disruption if there is something on the other end that is only used once in a blue moon but I don't know about it.

 

[kac77]

iftop

syntax would be:

iftop -i eth0

 

[Proxy]

iftop

syntax would be:

iftop -i eth0

Does so can I append the tcpdump counter to that to automate it?

#!bin/bash

mkdir /home/admin/ifscounters

iftop -c 20 -e -i eth0 >> /ifscounters/ifs.txt
iftop -c 20 -e -i eth1 >> /ifscounters/ifs.txt
iftop -c 20 -e -i eth2 >> /ifscounters/ifs.txt