be aware of ip stealing
 

Hello,

My linux box network it's very unstable, I think that someone is stealing my ip address, it's static. How can I know when or if that situation occurs? (Besides losing connection to the host via ssh).

Thanks.

No one can "steal" your IP - they would be experiencing the same unstable connection you are, as an arp storm would arise. In other words, they are not productively using the IP address, but they could intentionally disrupt your connection. If you suspect this for some reason, contact your ISP. They can easily verify by examining their arp caches.

Your service provider may not be providing a stable connection. Your DNS may not be reliable (does access by IP address work reliably?). Your infrastructure may not be stable - make sure your own house is in order first.

After a certain time of inactivity? Or even when typing, suddenly?

Even when typing.

I'm not concerned with ISP, DNS or whatever. Think my environment as a small network with 3 computers with static ip's. One has ip X, other ip Y, if the 3rd computer gets configured with the X ip, I want something in the 1st computador that detects ip conflicts, like Micrsofot Windows reports that someone else is using the ip. I don't need anything in realtime, just something in a log or something like that.

Many distributions will log an address conflict when they receive a gratuitous arp for the same address. Have you checked /var/log/messages?