[SOLVED] Can't access anything outside my network

Dario · 2013-07-29 15:11:37

Hi everybody.

I've a recently installed ArchLinux machine that used to work up to this morning. I configured the network with netctl, and the configuration is straightforward.
The problem is that I can't reach anything outside my local network. I can't ping nor resolve anything that is outside 192.168.2.*.
Everything was working nicely up to today, then someone pulled the mains out, the machine became unreachable so I had to manually access it.
I tried to start the network with dhcpcd, and I successfully obtained an IP lease etc. but the problem persists. Other machines works nicely with static or dhcp-assigned addresses, so I suspect something obvious is wrong somewhere, but still outside my reach. I tried using another address, but still I had no joy. Pinging anything (ip or name) just ends out in an eternal wait.

Here is the netctl profile I'm testing now:

Interface=enp2s0
Connection=ethernet
IP=static
Address=('192.168.2.99/24')
Gateway='192.168.2.1'
DNS=('8.8.8.8')

Maybe someone can shed light upon me.

Thanks in advance,

Dario

Last edited by Dario (2013-07-31 12:25:19)

ewaller · 2013-07-29 15:40:01

Can you ping 192.168.2.1? Are you certain that is your Gateway?
If that Gateway is your router, most consumer routers have a web server for administration. Can you browse to 192.168.2.1 ?
Are you trying to ping by name? Have you tried pinging using an IP? Try 66.211.214.131 (an Arch Linux box)

Dario · 2013-07-29 19:35:43

Hi!

ewaller wrote:

Can you ping 192.168.2.1? Are you certain that is your Gateway?

Yes, that's the right gateway. It's the same for the other machines in the office, by the way, and it used to work until today.

ewaller wrote:

If that Gateway is your router, most consumer routers have a web server for administration. Can you browse to 192.168.2.1 ?

I can browse to it - well, actually I can ping it from the arch box, that is an x-less server, and browse to it from the other machines (but I don't have the password yet - still, as I said, it used to work flawlessly,and it still does for the other machines...).

ewaller wrote:

Are you trying to ping by name? Have you tried pinging using an IP? Try 66.211.214.131 (an Arch Linux box)

I can't ping anything either by name or by IP. I know, that's odd, it's like packets directed outside the local network are sent to void.
Could it be possible that somehow that machine was blacklisted by the router? Otherwise, is there any point in a linux box system configuration that could interfere with proper packet routing?

By the way, this is a spare box that I decided to use as a arch linux server in order to learn something, and from this point of view this episode is a good chance:)

Thanks for the answer!

Dario

ewaller · 2013-07-29 19:48:30

I don't have any good suggestions. Is it possible that another machine on your LAN is configured with your address?
Aside from that, I think you need to look at the router's configuration and routing tables

BGK · 2013-07-29 20:09:15

Hello,
Could you post your routing table after getting your dhcp lease?

route

Also what gives a traceroute to a foreign host?

traceroute 8.8.8.8

Do you happen to have more than one network interface?

EDIT:
By the way, you cannot resolve anything at the moment because you cannot reach your DNS server (8.8.8.8) which is outside your local network.

Last edited by BGK (2013-07-29 20:16:22)

Dario · 2013-07-30 15:16:45

Hi

BGK wrote:

Hello,
Could you post your routing table after getting your dhcp lease?
route

I tried

ip route

and it says

default via 192.168.2.1 dev enp2s0  metric 202
192.168.2.0/24 dev enp2s0  proto kernel  scope link  src 192.168.2.103  metric 202

and there's only a single network interface.

In the meantime I discovered that one of our web managed switch went postal after the last power outage, so I'm starting to think that the arch box is innocent and the problem lies somewhere else. I'm going to investigate this.

I thank you very much,

Dario

WonderWoofy · 2013-07-30 15:31:29

The 'route' command is provided by the net-tools package, which is also what provides ifconfig. So 'ip route' is probably the "non-deprecated" way of doing things these days. (Though I personally still use the old deprecated networking tools, as I slowly learn how to use the new iproute2 and iw packages)

BGK · 2013-07-30 18:26:51

Hello

Yeah sorry for the confusion, i find myself manipulating a lot of routing tables at work, mostly on old Debian boxes so using "deprecated" tools is kind of a reflex for me. My bad.

Back on the subject, while your next hop (192.168.2.1) might okay, other further routers could be malfunctioning as you seem to indicate (it's hard to tell without seeing the whole network arch). The traceroute thing could answer to this question. ( i hope traceroute is not deprecated either)
You could also check what's really going on on your interface by monitoring outgoing [mac destination] packets (should match your gateway mac addr) using tcpdump while trying to connect to foreign hosts, but traceroute is probably an easier way to make sure your routing table is correctly used by your machine (and i don't see why it wouldn't be)

Last edited by BGK (2013-07-30 18:28:57)

WonderWoofy · 2013-07-30 18:32:52

@BGK, just to clarify, I wasn't saying that your suggestion/preference was wrong. I was just simply pointing out why the OP was unable to run 'route' and instead resorted to 'ip route'. By all means, continue to use what works for you!

BGK · 2013-07-30 21:48:03

@WW: Oh i didn't take your comment the "bad way" i know you didn't mean that. It's just that being new to this very nice distro, i got so much to learn... so i was disappointed by not knowing those new tools are the new standard for bleeding edge distros. My English expression must be somewhat incorrect/misleading i guess.

Anyhow, i am not gonna hijack this thread any longer.
I'm eager to ear about Dario soon... since this case is rather interesting!

Cheers.

Last edited by BGK (2013-07-30 21:48:36)

progandy · 2013-07-30 22:25:53

A few days ago my gateway was having some problems, too (not available, no ip, something like that). In these times, "route" was hanging and not producing any output while "ip route" printed the current settings to my terminal.

Dario · 2013-07-31 12:21:07

Hi guys.

We changed the router (we've been given another one) and now everything is working ok. I'm glad the arch box was faultless, as it seems:)

By the way I noticed something that could be interesting. While the box was still malfunctioning, as BGK suggested I monitored the ICMP packets sent from the arch box and from another windows box to 8.8.8.8, and they were sent to two different MAC address. The windows box sent the packets to the old router's MAC, while the arch box sent them to the web managed switch. Strangely enough both the boxes were connected, through the same consumer mini-switch, to the same web managed switch. Now both send packets to the MAC of the new router. So the real cause of what happened is still unknown, but nonetheless the case could be considered closed.

I'd like to thank you very much, your help has been very valuable!

Ciao,

Dario

Last edited by Dario (2013-07-31 12:45:17)

Arch Linux

#1 2013-07-29 15:11:37

[SOLVED] Can't access anything outside my network

#2 2013-07-29 15:40:01

Re: [SOLVED] Can't access anything outside my network

#3 2013-07-29 19:35:43

Re: [SOLVED] Can't access anything outside my network

#4 2013-07-29 19:48:30

Re: [SOLVED] Can't access anything outside my network

#5 2013-07-29 20:09:15

Re: [SOLVED] Can't access anything outside my network

#6 2013-07-30 15:16:45

Re: [SOLVED] Can't access anything outside my network

#7 2013-07-30 15:31:29

Re: [SOLVED] Can't access anything outside my network

#8 2013-07-30 18:26:51

Re: [SOLVED] Can't access anything outside my network

#9 2013-07-30 18:32:52

Re: [SOLVED] Can't access anything outside my network

#10 2013-07-30 21:48:03

Re: [SOLVED] Can't access anything outside my network

#11 2013-07-30 22:25:53

Re: [SOLVED] Can't access anything outside my network

#12 2013-07-31 12:21:07

Re: [SOLVED] Can't access anything outside my network

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