Abnormally High Upload Network Usage
I have been running 4 servers on VMs (2 DNS, 1 web, 1 mail server), which I have been running untouched and very reliable for months now with ISPconfig perfect setups on Centos 5.4 (all of them). Recently,
I have been experiencing very slow web surfing which I share BW with my servers.
I checked to find on my vm console that all my servers have been using all of my Upload BandWidth (barely any download BW). I don't know what is being uploaded and to whom, but all 4 servers are using equal amounts of BW i.e. 25% each. The duration of max BW can last for a couple of hours at Max then momentary lays idle for a few minutes and max out again. CPU usage on all servers (all single core) is under 25%.
My yum update times out during these max BW periods.
Any one has experienced this?
BTW if I switch off my DNSs the other servers BW goes idle.
1. Have my severs been compromised? ->how to check?
2. Or is this some external BW attack? -> spiders?
3. Or its normal - just set somthing wrongly?
My linux skills are at novice level so please keep advice simple.