Wierd routing problem?

[oeginc]

I have a proxmox server sitting at our data center running about 30 VM's, mixed OVZ and KVM.

From every ISP I've tried except Comcast, I can access all of my VM's and run traceroutes to each one just fine...

From Comcast, I can access all of my VM's except for one. Traceroutes to that VM shows the server as the last hop...

Any clue as to what could possibly be causing this? I've checked my Comcast firewall, host files, etc. I am stumped as to where to look at this point.

Anyone have any suggestions?

Thanks in advance!

 

[dswartz]

What is the problematic guest?

 

[oeginc]

It is an OVZ machine running debian (all VMs are running debian on this box). I've compared the routing tables and network configuration between this machine and a working machine and they all look the same (sans different IP addresses, but still on the same subnet).

 

[dswartz]

Is there any kind of iptables that might be blocking the comcast traffic? What do you see (if anything) is you do a tcpdump on the ethernet interface on the guest while trying to reach it from the comcast address?

 

[oeginc]

Well, that's wierd... I didn't try that originally because I've had problems doing tcpdump's on guests in the past, so I just assumed... You know what that makes me..

Never the less, the guest is seeing in the incoming packets and apparently sending replies from the looks of it, but I never get them... Which leads me to believe that Comcast is blocking packets from this particular IP address for some reason...

 

[dswartz]

Aha, I wonder if they have that block blacklisted?

 

[oeginc]

I supposed, except the rest of the machines on that block are accessible, it's just that one that I can't access, which is why it's wierd. I'll check with Comcast and see what they say.

 

[dswartz]

Possibly that host is blacklisted though.