Ubuntu: I cannot reach internet

Question

I'm trying to install nodejs on my Ubuntu server but it seems not to be able to reach the internet.

My server has two network interfaces:

1. eth0 connected to my network
2. eth1 used sometimes to be connected to a second network and usually not used.

My network gateway is 192.168.0.1 on a common class C network.

When I try to ping any host inside my network, everything goes fine but when I try to ping the gateway, I can't receive any response and the same happens when I try to ping any external domain, regardless of the correct name resolution provided by my DNS.

Here is my configuration:

ifconfig:

root:~# ifconfig

eth0      Link encap:Ethernet  HWaddr a4:5d:36:c3:44:18
          inet addr:192.168.0.168  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::a65d:36ff:fec3:4418/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:31531 errors:0 dropped:108 overruns:0 frame:0
          TX packets:6734 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:3896820 (3.8 MB)  TX bytes:930411 (930.4 KB)
          Interrupt:16

eth1      Link encap:Ethernet  HWaddr a4:5d:36:c3:44:19
          inet addr:192.168.1.1  Bcast:192.168.1.255  Mask:255.255.255.0
          UP 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)
          Interrupt:17

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:16 errors:0 dropped:0 overruns:0 frame:0
          TX packets:16 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:68235 (68.2 KB)  TX bytes:68235 (68.2 KB) 

my routes:

root@:~# ip route show
default via 192.168.0.1 dev eth0
192.168.0.0/24 dev eth0  proto kernel  scope link  src 192.168.0.168
192.168.1.0/24 dev eth1  proto kernel  scope link  src 192.168.1.1

/etc/network/interfaces

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
        iface lo inet loopback

auto eth0
        iface eth0 inet static
        metric 0
        address 192.168.0.168
        netmask 255.255.255.0
        network 192.168.0.0
        broadcast 192.168.0.255
        gateway 192.168.0.1
        dns-nameservers 192.168.0.3 192.168.0.2

auto eth1
        iface eth1 inet static
        metric 1
        address 192.168.1.1
        netmask 255.255.255.0
        gateway 192.168.0.168
        dns-nameservers 192.168.1.1 192.168.0.168

Where is the problem?

Answer 1

Please edit /etc/sysctl.conf and add these lines to the bottom:

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1

then run command

sysctl -p

use sudo if you are not logged in as root. Then you should see this on the terminal:

net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1

and

cat /proc/sys/net/ipv6/conf/all/disable_ipv6

should give output of

1

Then try pinging the 192.168.0.1 IP address again again.

EDIT

Seems like commenting out the IPV6 entries in /etc/hosts file were also needed. Figured out after a chat session.

Answer 2

You cannot have two default gateways. Remove the gateway command under auto eth1.

If you can't ping your gateway and it is connected to the same switch (or is the switch) you have problem not associated with gateways. Can other machines talk to the gateway, or is it the problem?

Comment out eth1's setup to avoid issues until fixed.