eth0 link is down

[usman1644]

Hello to everybody

I am using Raspberry Pi 3. My raspberry pi 3 eth0 link is down.
Can anybody tell me how I can activate my raspberry eth0?
Which command can I use for activating the eth0 activation?





Best Regards
Usman

[B.Goode]

Welcome to the Raspberry Pi forums.

I am using Raspberry Pi 3. My raspberry pi 3 eth0 link is down.
Can anybody tell me how I can activate my raspberry eth0?
Which command can I use for activating the eth0 activation?

Is there an Operating System running on your RPi?

If you are using the Raspberry Pi Foundation recommended and supported Raspbian Operating System on your RPi no intervention should be needed.

Simply connect a standard utp/rj45 'Ethernet' cable between the Ethernet jack on the RPi and a working network outlet that is connected to your local area network. If the lan has a DHCP server configured to allocate a dynamic IP address the RPi should respond automatically to that and thus join the network with no user action required.

If that isn't happening: check that the cable and network outlet are working by testing with some other device such as a laptop or desktop pc.

Have you made any changes to the Operating System that might prevent this automatic process from working?

Is this a 'home' network provided as part of a domestic broadband internet connection, or some sort of workplace or institution network in an office or dorm? If the latter, there might be security measures in place to prevent unauthorized access.

[lmarmisa]

The commands ethtool and ifconfig could help to diagnose your problem.

Type these commands for installing ethtool[/b (you will need access to the Internet)]:

Code: Select all

sudo apt-get update
sudo apt-get install ethtool

This example belongs to an old RPi 2:

Code: Select all

pi@rpi:~ $ ethtool eth0
Settings for eth0:
	Supported ports: [ TP MII ]
	Supported link modes:   10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	Supported pause frame use: No
	Supports auto-negotiation: Yes
	Advertised link modes:  10baseT/Half 10baseT/Full 
	                        100baseT/Half 100baseT/Full 
	Advertised pause frame use: Symmetric Receive-only
	Advertised auto-negotiation: Yes
	Link partner advertised link modes:  10baseT/Half 10baseT/Full 
	                                     100baseT/Half 100baseT/Full 
	Link partner advertised pause frame use: No
	Link partner advertised auto-negotiation: Yes
	Speed: 100Mb/s
	Duplex: Full
	Port: MII
	PHYAD: 1
	Transceiver: internal
	Auto-negotiation: on
Cannot get wake-on-lan settings: Operation not permitted
	Current message level: 0x00000007 (7)
			       drv probe link
	Link detected: yes
pi@rpi:~ $ ifconfig 
eth0      Link encap:Ethernet  HWaddr b8:27:eb:57:87:84  
          inet addr:192.168.1.58  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::1f11:f7ea:e8e9:2eaf/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:7553978 errors:0 dropped:83000 overruns:0 frame:0
          TX packets:7521642 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:1523977193 (1.4 GiB)  TX bytes:1257151240 (1.1 GiB)

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:16202 errors:0 dropped:0 overruns:0 frame:0
          TX packets:16202 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1 
          RX bytes:1959843 (1.8 MiB)  TX bytes:1959843 (1.8 MiB)

pi@rpi:~ $

[lmarmisa]

You can find the info provided by the command ethtool in the directory /sys/class/net/eth0 .

Code: Select all

pi@rpi:~ $ cd /sys/class/net/eth0
pi@rpi:/sys/class/net/eth0 $ ls -l
total 0
-r--r--r-- 1 root root 4096 May 13 22:44 addr_assign_type
-r--r--r-- 1 root root 4096 May 13 22:44 addr_len
-r--r--r-- 1 root root 4096 May 13 22:44 address
-r--r--r-- 1 root root 4096 May 13 22:44 broadcast
-rw-r--r-- 1 root root 4096 May 13 22:44 carrier
-r--r--r-- 1 root root 4096 May 13 22:44 carrier_changes
-r--r--r-- 1 root root 4096 May 13 22:44 dev_id
-r--r--r-- 1 root root 4096 May 13 22:44 dev_port
lrwxrwxrwx 1 root root    0 May 13 22:44 device -> ../../../1-1.1.1:1.0
-r--r--r-- 1 root root 4096 May 13 22:44 dormant
-r--r--r-- 1 root root 4096 May 13 22:44 duplex
-rw-r--r-- 1 root root 4096 May 13 22:44 flags
-rw-r--r-- 1 root root 4096 May 13 22:44 gro_flush_timeout
-rw-r--r-- 1 root root 4096 May 13 22:44 ifalias
-r--r--r-- 1 root root 4096 May 13 22:44 ifindex
-r--r--r-- 1 root root 4096 May 13 22:44 iflink
-r--r--r-- 1 root root 4096 May 13 22:44 link_mode
-rw-r--r-- 1 root root 4096 May 13 22:44 mtu
-r--r--r-- 1 root root 4096 May 13 22:44 name_assign_type
-rw-r--r-- 1 root root 4096 May 13 22:44 netdev_group
-r--r--r-- 1 root root 4096 May 13 22:44 operstate
lrwxrwxrwx 1 root root    0 May 13 22:44 phydev -> ../../../../../../../../../../virtual/mdio_bus/usb-001:008/usb-001:008:01
-r--r--r-- 1 root root 4096 May 13 22:44 phys_port_id
-r--r--r-- 1 root root 4096 May 13 22:44 phys_port_name
-r--r--r-- 1 root root 4096 May 13 22:44 phys_switch_id
drwxr-xr-x 2 root root    0 May 13 22:44 power
-rw-r--r-- 1 root root 4096 May 13 22:44 proto_down
drwxr-xr-x 4 root root    0 May 13 22:44 queues
-r--r--r-- 1 root root 4096 May 13 22:44 speed
drwxr-xr-x 2 root root    0 May 13 22:44 statistics
lrwxrwxrwx 1 root root    0 May 13 22:44 subsystem -> ../../../../../../../../../../../class/net
-rw-r--r-- 1 root root 4096 May 13 22:44 tx_queue_len
-r--r--r-- 1 root root 4096 May 13 22:44 type
-rw-r--r-- 1 root root 4096 May 13 22:44 uevent
pi@rpi:/sys/class/net/eth0 $

Code: Select all

pi@rpi:/sys/class/net/eth0 $ cat operstate 
up
pi@rpi:/sys/class/net/eth0 $ cat speed 
100
pi@rpi:/sys/class/net/eth0 $

I have listed a couple of files but feel free to explore other files and directories (for example statistics).

[n67]

You can find the info provided by the command ethtool in the directory /sys/class/net/eth0 .

Thank you!!!

What I am about to say is not exactly on-topic in this thread, but I have been looking for something like this - that is, something in the pseudo-directories (i.e., /sys and/or /proc) that enumerates the network devices - for a very long time.

Among other things, this could be used to answer a question I see posted from time to time here - which is, "How do I figure out, programmatically, which device (of wlan0, wlan1) is the built-in WiFi and which is from a USB wireless dongle?".