route:

Question

1

Only killing eth0 enables internet

rated 0 times [ 1] [ 0] / answers: 1 / hits: 2582 / 3 Years ago, tue, september 14, 2021, 5:29:05

I connect to wifi and ifconfig report 3 interfaces (lo, eth0 and wlan0), but I cannot ping anything, including the router.

Only after ifconfig eth0 down I get to actually use the internet.

What is going on? How do I avoid this problem?

My /etc/network/interfaces:

auto lo wlan0

iface lo inet loopback

route:

before ifconfig eth0 down:

Kernel IP routing table

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface

0.0.0.0         192.168.7.1     0.0.0.0         UG    0      0        0 wlan0

169.254.0.0     0.0.0.0         255.255.0.0     U     1000   0        0 wlan0

192.168.7.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0

192.168.7.0     0.0.0.0         255.255.255.0   U     2      0        0 wlan0

after ifconfig eth0 down:

Kernel IP routing table

Destination     Gateway         Genmask         Flags Metric Ref    Use Iface

0.0.0.0         192.168.7.1     0.0.0.0         UG    0      0        0 wlan0

169.254.0.0     0.0.0.0         255.255.0.0     U     1000   0        0 wlan0

192.168.7.0     0.0.0.0         255.255.255.0   U     2      0        0 wlan0

ifconfig

before ifconfig eth0 down:

eth0      Link encap:Ethernet  HWaddr 00:90:f5:a6:6c:de  

          inet addr:192.168.7.100  Bcast:192.168.7.255  Mask:255.255.255.0

          UP BROADCAST RUNNING 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:45 



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:16436  Metric:1

          RX packets:430 errors:0 dropped:0 overruns:0 frame:0

          TX packets:430 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0 

          RX bytes:34157 (34.1 KB)  TX bytes:34157 (34.1 KB)



wlan0     Link encap:Ethernet  HWaddr 74:f0:6d:27:3e:4d  

          inet addr:192.168.7.156  Bcast:192.168.7.255  Mask:255.255.255.0

          inet6 addr: fe80::76f0:6dff:fe27:3e4d/64 Scope:Link

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:8 errors:0 dropped:0 overruns:0 frame:0

          TX packets:58 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000 

          RX bytes:878 (878.0 B)  TX bytes:10870 (10.8 KB)

after ifconfig eth0 down:

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:16436  Metric:1

          RX packets:1435 errors:0 dropped:0 overruns:0 frame:0

          TX packets:1435 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0

          RX bytes:116494 (116.4 KB)  TX bytes:116494 (116.4 KB)



wlan0     Link encap:Ethernet  HWaddr 74:f0:6d:27:3e:4d

          inet addr:192.168.7.156  Bcast:192.168.7.255  Mask:255.255.255.0

          inet6 addr: fe80::76f0:6dff:fe27:3e4d/64 Scope:Link

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:63915 errors:0 dropped:0 overruns:0 frame:0

          TX packets:50926 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000

          RX bytes:95400944 (95.4 MB)  TX bytes:4750543 (4.7 MB)

Answers

Only authorized users can answer the question. Please sign in first, or register a free account.

percol

Add To Favorites

Follow

Total Points: 493

Total Questions: 116

Total Answers: 107

Location: Taiwan

Member since Mon, Sep 6, 2021

3 Years ago

percol questions

1 Unable to connect with the hotspot created on ubuntu

Thu, Sep 29, 22, 07:42, 2 Years ago

1 Find a directory with a prefix in name

Sat, Jul 16, 22, 21:00, 2 Years ago

1 Where can I download ubuntu image with 5.11.0-27-generic kernel?

Tue, Feb 14, 23, 04:14, 1 Year ago

1 Does Ubuntu Server have any special preinstalled packages

Tue, May 30, 23, 19:16, 1 Year ago

1 Bluetooth settings won't open Ubuntu 20.04

Wed, Aug 18, 21, 02:15, 3 Years ago

View All

answered 3 Years ago gerrin · Accepted Answer

By looking at the comments & I've added as an answer expanding more.

Possible cause is that IP's are assigned to the interface statically instead requesting automatically by adding a gatway too (just an assumption). If there are multiple gateways though the subnet is same, system does not know where to look into unless there's a persistent/static route added separately.

You may click on the nm-applet () & select Edit connections to get the entire network manager preferences or you may achieve this using terminal (press CTRL+ALT+T) & key-in below;

nm-connection-editor            # this will give you below nm-editor screen

enter image description here

Navigate to Wired tab, select the profile & click edit or either delete if necessary. If editing, then navigate to IPv4 settings select the Method as Automatic (DHCP) for the eth0 to request IP from an available DHCP server (see below screen);

enter image description here

Once done, restart the network manager to re-authenticate to the network.

sudo service network-manager restart

And as you requested, all saved network profiles can be found under system-connections directory. You may edit/delete in there but I'd recommend to use the GUI if you're to create a new connection profile. Below are the command to view your current network profiles.

 cd /etc/NetworkManager/system-connections/    # will change in to the directory

ls -l                                          # will display all the profiles in a sequense

sudo rm -fr profile_name                       # you will need root to add/edit/delete & this will remove a specified profile

Hope this helps!! :)