Connected to router but cannot access internet/ssh/ping e.t.c
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Connected to router but cannot access internet/ssh/ping e.t.c
Some very weird behaviour going on with my network connection. I am connected to my router via ethernet (have also tried wireless with the same effect) but I cannot connect to the internet. I am going to call this computer computer A from now on.
I am currently typing on another computer (computer B) connected to the same router in exactly the same way, and this one is fine.
Other effect:
a) If I log into my router I can see that computer A is connected at 192.168.0.6
b) When I try to ssh into computer A from computer B I get:
ssh: connect to host 192.168.0.6 port 22: No route to host
c) When I try to ping computer A I get:
From 192.168.0.2 icmp_seq=1 Destination Host Unreachable
d) When I try to ssh into computer B from computer A it ssh's into itself??!??!?
e) When I try to ping www.google.com from computer A I get nothing
f) When I try to ping 173.194.66.147 (which is www.google.com) from computer A I occasionally get something but this is very glitchy.
At first I thought it was my resolv.conf, so I tried changing this to be the same as the working computer. This is included below:
Code:
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 192.168.0.1 # ip address of my router
nameserver 127.0.1.1
search Home
nameserver 208.67.222.222
nameserver 208.67.220.220
this is the output from some key commands:
Code:
#dmesg |grep eth #check what is recognized
[ 0.092335] reboot: BIOS series board detected. Selecting HP Compaq Laptop-method for reboots.
[ 0.140073] [Firmware Bug]: ACPI: No _BQC method, cannot determine initial brightness
[ 1.552326] b44: Broadcom 44xx/47xx 10/100 PCI ethernet driver version 2.0
[ 1.573818] b44 ssb0:0 eth0: Broadcom 44xx/47xx 10/100 PCI ethernet driver 00:15:60:cb:dd:3c
[ 16.094067] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[ 16.763273] [Firmware Bug]: ACPI: No _BQC method, cannot determine initial brightness
[ 20.609954] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[ 20.610327] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[ 23.804222] b44 ssb0:0 eth0: Link is up at 100 Mbps, full duplex
[ 23.804230] b44 ssb0:0 eth0: Flow control is off for TX and off for RX
#iwconfig #unsure what you connect with
lo no wireless extensions.
eth0 no wireless extensions.
wlan0 IEEE 802.11abg ESSID:off/any
Mode:Managed Access Point: Not-Associated Tx-Power=off
Retry long limit:7 RTS thr:off Fragment thr:off
Power Management:on
Code:
#route -n #get route table
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.0.1 0.0.0.0 UG 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 eth0
192.168.0.0 0.0.0.0 255.255.255.0 U 1 0 0 eth0
Code:
#uname -a #kernel ?
Linux maeldeb 3.8.0-22-generic #33-Ubuntu SMP Thu May 16 15:17:59 UTC 2013 i686 i686 i686 GNU/Linux
Forget all that. Can you reliably ping your router?
Also, let's try some other bits and bobs... can you ping your DNS server IP? what about 8.8.8.8?
if you can't do this stuff, let's do it again, but also run "tcpdump -i eth0 -ven" and post the output from that whilst your pinging - including the other computer IF you can hit the router OK
Last edited by acid_kewpie; 07-04-2013 at 07:09 AM.
Thanks for your help. I can ping 192.168.0.1 (my router) and 127.0.1.1 (not sure what this is, is it my router again?) but nothing external, and not 8.8.8.8.
But from what I can see, you never reply. Maybe as you're on Sky broadband, your machine is anti Murdoch..?
So, why isn't your box replying to the ARP requests? is iptables blocking them somehow? Sounds a bit nutty to me, but let's see what "iptables -vnL" says, maybe there's something really odd there. Could there be a different device also on that IP? a smartphone or console? maybe try changing the IP to something different, like 192.168.0.123, leaving the other settings as they are.
to check for duplicated addresses, try a "arping -D 192.168.0.6" maybe something else will show up that way.
Last edited by acid_kewpie; 07-04-2013 at 07:47 AM.
Yes, it's like every local ip is getting routed back to the computer itself. When I ssh out to another computer it logs me back into the computer I am ssh'ing from.
I also have apache2 installed. I have been stopping this as I thought it may be causing issues. But when I have it running and I try to go to my router's ip, 192.168.0.1, in the browser, it brings up the website hosted by the apache server.
Anyway, the output from "iptables -vnL" says
Code:
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
and from "arping -D 192.168.0.6" return not a lot
Code:
ARPING 192.168.0.6 from 0.0.0.0 eth0
Sent 39 probes (39 broadcast(s))
Received 0 response(s)
Does the router have any Port Forwarding rules that point to 192.168.0.6? Maybe that's misconfigured.
It appears that your computer thinks it owns 192.168.0.1 ... let's try this:
ifconfig lo # the loopback interface; write down the number of packets RX'd and TX'd
ping -f 192.168.0.1 # flood ping the IP address for about 10 seconds....
# ... You may have to use `sudo ping -f 192.168.0.1`
<ctrl>-c # to stop the flood ping
ifconfig lo # compare the number of TX'd and RX'd packets
Any packets from the local machine to the local machine will go through the loopback interface (lo). If you see a large increase in packets as a result of this test then the local machine thinks it owns 192.168.0.1 and is routing the packets through the loopback interface. On my machine this test incremented the RX and TX counter by about 2 million in 10 seconds.
If this happens with yours, 192.168.0.1 _should_ show up in the output of `ifconfig -a`, but it doesn't... weird.
Try the ping test that Acid-Kewpie suggests but this time monitor the loopback interface:
"tcpdump -i lo -ven"
The output from "tcpdump -i eth0 -ven" above doesn't necessarily mean the router is asking for computer "A"s IP because of the ping. It may be looking for it for another reason, such as port-forwarding or nameserver replies. We should see the icmp echo request first, but we're not, so I don't think the "who-has X tell Y" lines are due to the ping. It does appear that the default route is working because we see nameserver queries going out:
" .... 192.168.0.6.48804 > 208.67.222.222.53: ...." that's probably what the arp-requests are from.
Your resolv.conf file should lose the "nameserver 127.0.1.1" line. This would only be valid if you have a nameserver configured and running on the local machine and you corrected the typo and made the entry "nameserver 127.0.0.1"
Does computer A get it's network config via DHCP or statically?
Are you mapping 00:15:60:cb:dd:3c to 192.168.0.6 in the router's DHCP?
Last edited by MikeDeltaBrown; 07-05-2013 at 09:49 AM.
Reason: Removed double post.
Finally, the computer is obtaining its address dynamically. It was originally static, on 192.168.0.100 which had firewall rules set on the router to allow ssh and http connections, but I changed this whilst trying to get it to work again.
Thanks for the help
Last edited by sparkinson; 07-04-2013 at 10:30 AM.
Reason: added more info
OK, it looks like there is something running on your machine that is configured as 192.168.0.1.
Do you have any Virtual Machine software running like VMWare, VirtualBox, or Parallels? If so, one of the clients may have its virtual interface bridged with Computer A's and configured with the same IP address as your router.
Also, you still have "nameserver 127.0.1.1" in your /etc/resolv.conf. That needs to go away.
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Can you reliably ping your router?
