No route to internet - DNS Working, connected networks reachable
 

Hello,

First off, Thank you for reading this ;)

I seem to have run into a little problem which I am not able to solve myself at this time. Maybe due to me forgetting something or its just a weird issue.


The problem:
"Server" is connected to 2 networks and 1 virtual network. The server doesnt seem to be able to have a route to any host on the internet. But can reach any system on any of the networks connected without issue.

The layout:

Network 2
Closed from the rest of the world, no internet.
Lets say: IP range 10.0.0.x
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p16 - IP 10.0.0.2

vir1 - IP 192.168.2.2 ----------- Virtual network IP range 192.168.2.x

Server
Running: Fedora 17 x86_64, fully updated

p6 - IP 192.168.1.2
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Network 1
Connected to the internet through a 'router'
IP range: 192.168.1.x
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IP 192.168.1.1

Router

External IP
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The internet




What does work:
Connecting to the server. From: Inside network 1,2,virt and the internet.
Connecting from the server. To: Any system inside network 1,2 or virtual.
Resolving Host names. Any hostname (that exists ofcourse) can be resolved on the server itself.

What have i tried: (just to try and connect to the internet)
Using METRIC to prioritise the network connections
Setting a default gateway to 192.168.1.1
Running interfaces without the network manager
Updating the system (no updates for network stuff found)
Smashing my keyboard with a hammer (no real effect here)
And ofcourse connecting to the internet with any other system connected to Network 1 (this works without issue)

What i have not tried yet:
Disabeling all other network interfaces besides the one to Network 1 (Can not do this at this time due to system online requirements for network 2 at this moment)


Any help here would be very nice, thank you
--
Martin

Well... just the obvious:

- are you natting traffic going out to internet on the router?
- when you try to go to the internet, are you tracing on the interface to see if traffic is being sent to the router?

other things that might help:

Ah yes, that information might be helpfull aswell:

Forwarding anything, any BIND or routing enabled: No.
The system is running virtual machines which are connected to Network 1, Bridged to p6. (these systems have a fully working internet connection)

I am not formilliar with tracing network packages without any GUI. (And GUI's at this moment do not want to install due to the lack of a internet connection for the yum package manager. (note here that for some reason it updated before, but from that moment on yum cant connect aswell)

I did run the "ip" commands you sudgested, these said nothing more then i could read from "ifconfig" and the files in "/etc/sysconfig/networking-scripts/" except for one thing:
What i then thought of though, stupidly enough i hadent before:
So if i am correct the route does go trough the correct network, but why not through the router. This raises more questions then it solves but at least it aims my attention to the router instead of the server. (please correct me if im wrong)

Maybe ill flash the router with custom firmware if availible, or ill contact their support line. Thank you for aiming me in the right direction.


Though now an other issue has come up... for some reason the virtual machine connected to Network 2 can no longer connect to Network 2 IP adresses. Ill have to look into that later.

--
Martin

If someone where to know lots of stuff about D-Link routers, its a DIR-655

Who needs GUI? :-)

tcpdump can do that.

man tcpdump

Oh... virtual machines inside the host. Are you masquerading them? If not, does the router know how to "route" to them?

Well... the virtual machine problem was easelly fixed, just a firewall/interface messup due to temporaraly disaballing one network interface on the host.

The no internet issue however:
As far as i know it sends it over the correct port.
Or at least, the http requests go there, no reply what so ever though.

What does work for some reason aswell: (all though be it very very slow)
when pinging from a other (Windows) machine in Network 1:
So... i am confused.

Ok.... provide us with the basics for the server that has the problem:

Ok, i will. I will replace some stuff with random stuff ofcourse (which is also the reason why i didnt post this before, security and all that)

ip link show:
ip addr show
ip route show
That should be it

What is this p13p1 in detault via? I would expect it to be p6, don't you think?

Whoops sorry, yeah it is actually, or better said all p6's are p13p1's :redface:
Sorry about that, i just renamed them at my first post (not being able to view the actual ports from where i posted the first post)
I just changed it so that it is correct in the previous post.

Ok.... given that routing looks OK, I would point to the problem being on the router. What I would do? I would trace traffic (tcpdump, tshark) sent to internet both on the server end and the router end to see if it's reaching the router.... if you can also take a look at the traffic coming out of the router to internet, that would be a great plus.

In order for internet to be reacheable by your server a number of things have to happen. Normally:

- traffic not being filtered on the router
- traffic going to internet natted by the router
- traffic not filtered by your own server. Take a look at iptables to see if there's something strange (iptables -L -nv, iptables -t nat -L -nv)

sniffers are your friends to detect where the problem is.

Ill mark this as SOLVED, since its not Linux (well the router is linux based but nvm that) that causes the issue. Thanks all for thinking with me and esp eantoranz for the usefull replies.