CentOS no internet
 

hello guys, need your help.

got a Linux Centos box, it's not able to connect to internet.

Centos Box is on DMZ network.
IP set as static.
DNS set as static (DNS are public IP).

Can ping other Linux machines on the DMZ. and other Linux machine can also ping this CentOS box.

every time I ping a public DNS such as 8.8.8.8 it's not able to connect 100% packet loss.


Centos is able to ping gateway.

any ideas is greatly appreciated. Thank you.

Check your routing
 

Is your gateway set as the default route on this box? It appears that routing to the world is what is broken, so that may be the only missing piece.

How rounting table looks. You said you are able to ping the default gateway. Does your route table shows the correct default gateway? Use and check the output.

If routing table is correct and you are able to ping the default gateway then you have to check something on the router from which the traffic is going to internet and check whether this machine is allowed to access internet?

It will be good to take a packet trace and see what exactly is going on.

i tried route -v

the default gateway is the correct subnet

ip - 192.168.1.25
gateway - 192.168.1.1 (gateway same as other linux)

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subnet
 

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it's actually setting on a Hyper-V box.

but if i just use the internal network not the DMZ the Centos box is able to connect to the internet.

When you say internal network I am assuming private internet network. So that is it you have to check that what happens when you do it via DMZ. As I said it in my previous post it will be good idea to run a packet trace to get more details. A better idea would be running packet trace on both you CentOS machine and the next hop which I am assuming to be your router in DMZ.

hi T3RMINVT0R can you guide me on how to do the packet trace?

Thanks.

one issue i notice my internal network (private network) is using DHCP and internet works fine.

DMZ needs to set static i guess that's where the issue comes out. there is no internet.

other Linux which are physical servers has no issues on the DMZ, only this centos box which is setting on hyper-v.

any one who has the same issue on hyper-v and able to solve it please help.

Thanks.

Here is the howto on taking packet capture: http://www.tecmint.com/12-tcpdump-co...-sniffer-tool/

You would also want to download wireshark as it is a pretty good tool for taking / analyzing packet captures.

If I am getting it correctly you have physical boxes in DMZ which can connect to internet. Hyper-V is one of the physical box in that DMZ and on top of that you have got CentOS guest running. If my assumption is correct then my first question will be if you are able to connect to internet from Hyper-V machine. If yes then this doesn't appear to an issue with the router / gateway instead it appears to be an issue with the bridge that is configured between guest (CentOS) and the host (Hyper-V)

It will be good to know how it has been set to connect to internet.

The guest CentOS running on Hyper-V is able to connect to the internet if it is set to DHCP and connected via private network.

But assigning static IP via DMZ, CentOS is only able to browse the DMZ but not the internet.

I had checked with Technet forum, they said it could be a Hyper-V issue.

Thanks.

Yes pretty much possible. If this is the first Guest on Hyper-V host and if never worked before then it is very much possible to be an issue with Hyper-V. Also, other physical boxes within DMZ with static IP are just working fine that explains.

Yes THEY just don't want to play well with Linux system.. I think so.. but VMWare I think should be fine but cost is one thing.

How significant this box is? If it is not of much importance then you can go with CentOS machine running KVM and on top of that you can create guest VMs.