1

Update: If i change the ip to 10.0.0.11 everything starts to work. 10.0.1.1 is still in the same range in a /22 subnet so it should still work?

I have a very peculiar problem with Ubuntu 14.04. I moved apartments and connected it to a new router with a new ip-range. I changed my laptops ip-address to the old range temporarily, ssh'd to the server and changed its static ip to match the new range:

auto p1p1
iface p1p1 inet static
    address 10.0.1.1
    netmask 255.255.252.0
    gateway 10.0.0.1
    dns-nameservers 8.8.8.8 8.8.4.4

Then i disconnected and ssh'd to 10.0.1.1, no problems. When i tried to sudo apt-get update the problems started. The connection would stall on Connecting to archive.ubuntu.com. A quick restart later the problem persisted. I tried a different network interface, it has one on the mainboard and one on a PCI card. No dice. Different cable, no dice. There is no firewall active on the server.

If i ping the default gateway 10.0.0.1 it says Destination host unreachable. arp -n says that the HWAddress of 10.0.0.1 is incomplete. If i ssh to the default gateway and ping the server, it responds fine! If i ping 10.0.3.255 -b i only get responses from my laptop which is on wifi. Somehow the Ubuntu server only sees my laptop and nothing else even though the connection is going through a wifi access point. There is also at least 10 other devices that should have responded. What in gods name is going on?

To recap:

  • Laptop on wifi and rest of network can reach internet just fine.
  • Laptop on wifi can reach cabled Ubuntu server.
  • Ubuntu server cannot ping anything but aforementioned laptop on wifi.
  • Ubuntu server arp -n shows default gateway as incomplete.
  • Default gateway can ping the Ubuntu server.
  • Network is 10.0.0.0/22.

Some command output that might be of interest:

  % ifconfig -a
 lo        Link encap:Local Loopback
           inet addr:127.0.0.1  Mask:255.0.0.0
           inet6 addr: ::1/128 Scope:Host
           UP LOOPBACK RUNNING  MTU:65536  Metric:1
           RX packets:5128 errors:0 dropped:0 overruns:0 frame:0
           TX packets:5128 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           RX bytes:985588 (985.5 KB)  TX bytes:985588 (985.5 KB)

 p1p1      Link encap:Ethernet  HWaddr b0:48:7a:80:**:**
           inet addr:10.0.1.1  Bcast:10.0.3.255  Mask:255.255.252.0
           inet6 addr: fe80::b248:7aff:fe80:19aa/64 Scope:Link
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:2744 errors:0 dropped:0 overruns:0 frame:0
           TX packets:2990 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:1000
           RX bytes:931523 (931.5 KB)  TX bytes:284296 (284.2 KB)

 p2p1      Link encap:Ethernet  HWaddr 54:04:a6:60:**:**
           BROADCAST MULTICAST  MTU:1500  Metric:1
           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:1000
           RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

.

  % ping 10.0.3.255 -b
 WARNING: pinging broadcast address
 PING 10.0.3.255 (10.0.3.255) 56(84) bytes of data.
 64 bytes from 10.0.0.44: icmp_seq=1 ttl=64 time=1.66 ms
 64 bytes from 10.0.0.44: icmp_seq=1 ttl=64 time=92.9 ms (DUP!)
 64 bytes from 10.0.0.44: icmp_seq=1 ttl=64 time=94.5 ms (DUP!)
 64 bytes from 10.0.0.44: icmp_seq=2 ttl=64 time=1.73 ms

.

  % arp -n
 Address                  HWtype  HWaddress           Flags Mask            Iface
 10.0.0.1                         (incomplete)                              p1p1
 10.0.0.44                ether   f4:5c:89:8b:**:**   C                     p1p1

.

  % route -n
 Kernel IP routing table
 Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
 0.0.0.0         10.0.0.1        0.0.0.0         UG    0      0        0 p1p1
 10.0.0.0        0.0.0.0         255.255.252.0   U     0      0        0 p1p1
Improve this question
2
  • This looks like some sort of packet filter on the router itself - maybe it allows only whitelisted IPs?
    – Eugen Rieck
    Commented Dec 10, 2016 at 20:29
  • No, no ip filters on the router. There are other devices with 10.0.1.x that work fine.
    – Maciej Swic
    Commented Dec 10, 2016 at 20:31

1 Answer 1

Reset to default
0

Instead of broadcast ping you should use arping to check router IP address

arping 10.0.0.1

I think that the mask on the router is wrong (like 255.255.255.252 instead of 255.255.252.0)

Improve this answer
7
  • The mask is correct s.swic.name/iPZM
    – Maciej Swic
    Commented Dec 10, 2016 at 20:53
  • Do you have a reply with arping ?
    – François
    Commented Dec 10, 2016 at 20:55
  • No, 100% loss. I have changed the Ubuntu server ip to 10.0.0.2 temporarily, that seems to work. As soon as i switch it back to 10.0.1.1 the issue comes back and arping gets no response from 10.0.0.1.
    – Maciej Swic
    Commented Dec 10, 2016 at 21:09
  • try to specifying network interface for arping.
    – François
    Commented Dec 10, 2016 at 21:19
  • Tried sudo arping 10.0.0.1 -i p1p1, 100% loss.
    – Maciej Swic
    Commented Dec 10, 2016 at 21:42

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