How do you determine if ethernet port(s) are bad in Ubuntu Linux?

Ok so I look this up and most guides tell what commands to use, but now what to actually look for that will help determine if the ethernet port is bad. Therefore, I did as follows, but how do I know my port or ethernet controller is bad because I can't ping my router or the other two computer on the network:


hostname:~$ sudo -i ethtool enp6s0
Settings for enp6s0:
Supported ports: [ TP ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Supported pause frame use: No
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Advertised pause frame use: No
Advertised auto-negotiation: Yes
Speed: Unknown!
Duplex: Unknown! (255)
Port: Twisted Pair
PHYAD: 1
Transceiver: internal
Auto-negotiation: on
MDI-X: Unknown (auto)
Supports Wake-on: pumbg
Wake-on: g
Current message level: 0x00000007 (7)
drv probe link
Link detected: no
hostname:~$ dmesg | grep enp6s0
[ 20.308671] e1000e 0000:06:00.0 enp6s0: renamed from eth0
hostname:~$ ^C
hostname:~$

I hope the ports aren't bad because there onboard, so if they are I'm going to need a new motherboard and that might be a problem because the board is 3 years old or almost 3 years old and I may not have much time to RMA if any.

I should also say that I've configured static Ip addresses on the machine and on the router with dhcp reservations, but the machine can't get an IP from the router no matter what I do.

Easiest method I know of:

Set static IP on your machine (don't rely on DHCP reservation for the moment)

Try a different cable. Bad cables are surprisingly common.

Try a different port on your switch/router.

Try to ping a different device than your router on the LAN.

Try to manually set the proper speed rather than rely on auto-negotiation

If all that fails to resolve the issue, get a USB NIC and try that for temporary cheap solution.

From what you have posted here - NIC isn't seeing a proper link, I would suspect cable first off, and work my way down from there.

scharfshutze009 said:

Speed: Unknown!
Duplex: Unknown! (255)
Auto-negotiation: on
Link detected: no

Click to expand...

bad cables are especially common when using PoE. @10% of the premade cables from monoprice fail for PoE.

Brian_B said:

Easiest method I know of:

Set static IP on your machine (don't rely on DHCP reservation for the moment)

Try a different cable. Bad cables are surprisingly common.

Try a different port on your switch/router.

Try to ping a different device than your router on the LAN.

Try to manually set the proper speed rather than rely on auto-negotiation

If all that fails to resolve the issue, get a USB NIC and try that for temporary cheap solution.

From what you have posted here - NIC isn't seeing a proper link, I would suspect cable first off, and work my way down from there.

Click to expand...

Thanks I tried another port, but that didn't work. I'm not sure a seven foot cable will reach instead of a 25 foot. My routers fine because the port works if I use it with my Wireless Access Point. Static IP's are already set in everything require and so is dhcp reservation. Speed is manually set in /etc/network/interfaces. The server is conneted to the interenet with a dual USB Ethernet adapter, so I guess that answers that question.

Perilous said:

bad cables are especially common when using PoE. @10% of the premade cables from monoprice fail for PoE.

Click to expand...

Thanks Perilous, but it looks like its both ports or the controller because the server can connect with a dual gigabit eithernet adapter. I bought this cable from Office Max years ago and it's 25 foot belkin. You should remember I brought it to your house with my Asus G74 before I sold the G74 years later and if not it's ok. Now the question is what should I do about the bad ports. Should I try to RMA the motherboard.

Have you tried another cable? Copper cables can and will deteriorate over time.