My VMWare ESXi 4 server appears to be under a Denial of Service attack. I am getting massive packet loss to the server (60+%) and am barely able to load any services on the VMs running on the host.
I have Cacti installed but cannot load it due to the attack. I can SSH in to the VMware host. Are there any commends I can run to either determine where the attack is coming from, or block all IP addresses except mine so that I can load Cacti again to troubleshoot?
I tried esxcli network firewall get but received: Unknown Object firewall in namespace network
All the VMs with network access are directly connected to the internet, that is, there is a virtual switch between the internet-facing VMs and the router.
EDIT: MDMarra had a great idea: disable the vswitch that the VMs are on. But I can't get the vSphere console to respond long enough to do this. Can this be done through SSH?
Answer
The ISP was unable to determine the cause of the traffic, but what they were able to do was null-route all the IP addresses assigned to this server at the network switch. Then, one-by-one we removed the null routes, until we determined which IP addresses were being attacked. Once the target IPs were null-routed, the problem went away and I am able to access the server again.
I am now going to console in to the affected VMs and start tcpdump, and then remove the null-routes to those VMs. This will allow me to find the source IPs of the attack, which can be blocked by my ISP before traffic from them enters the core network.
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