1

I am trying to check my whether my ethernet network interface is working properly or not. I have two PC's and they are connected directly(without a switch). In one PC I tried to ping the other one with IP assigned but I'm getting 'Destination Host Unreachable'. I checked wireshark and there I am getting both ARP request to and reply from the second PC( I am checking in 2nd PC). Then I checked the otherway around and found that my first PC is not replying to any ARP requests. Any idea of what is causing this error?

My settings: PC 1

ink encap:Ethernet  HWaddr 6c:b3:11:52:12:a5  
          inet addr:10.0.0.2  Bcast:10.0.0.255  Mask:255.255.255.0
          inet6 addr: fe80::66b3:11ff:fe52:2a9/64 Scope:Link
          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)
PC 2
ink encap:Ethernet  HWaddr 6c:b3:11:52:72:a0  
          inet addr:10.0.0.3  Bcast:10.0.0.255  Mask:255.255.255.0
          inet6 addr: fe80::66b3:12ff:fe52:2a9/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:8 errors:0 dropped:0 overruns:0 frame:0
          TX packets:284 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (480.0 B)  TX bytes:0 (34.4 KB)

From PC 1 , I tried ip route ls and I got

10.0.0.0/24 dev enp1s0  proto kernel  scope link  src 10.0.0.2

Saw some comments on firewall but heres what I get when I check

home# cat /etc/sysconfig/iptables                                                              
cat: /etc/sysconfig/iptables: No such file or directory

EDIT 1 : Result of ip route on PC2

home$ip route ls
default via 172.16.0.1 dev eth0 proto static
10.0.0.0/24 dev eth1 proto kernel scoope link src 10.0.0.3 metric 1
172.16.0.0/16 dev eth0 proto kernel scope link src 172.16.2.3 metric 1

Tried ping6 fe80::66b3:11ff:fe52:2a9 -I eth1 got Destination unreachable, address unreachable error Same result for otherway around

Note : (In case if its relevent) In PC2 I have two NICs and I am trying to communicate through eth1

1
  • 1
    What's the output of ip route on PC 2? Can you try to ping the machines via their link-local IPv6 addresses (as shown in the output of ifconfig). On older Ubuntu releases you need to use the ping6 tool for that since ping doesn't support IPv4 there yet. Mar 19, 2018 at 17:12

1 Answer 1

0

Operating under the assumption that you've connected the 2 PC's with a properly constructed cross-over cable or at least one of the devices support Auto-MDIX, I can only think of 2 reasons this might occur.

A) Blocked ICMP echo requests on port 7 via firewall

B) PC1's NIC is faulty (both transmitter and receiver have failed.) and should be replaced.

Note:

auto MDI-X is within the 1000BASE-T standard and also developed patented algorithms for "forced mode auto MDI-X" which allow a link to be automatically established even if the port does not auto-negotiate. This may or may not be implemented on a given device, so occasionally a crossover cable may still be necessary when connecting auto MDI-X to MDI-X (hub or switch), especially when auto-negotiation is deactivated.

Newer routers, hubs and switches (including some 10/100, and all 1 gigabit or 10 gigabit devices in practice) use auto MDI-X for 10/100 Mbit connections to automatically switch to the proper configuration once a cable is connected.

Gigabit and faster Ethernet links over twisted pair cable use all four cable pairs for simultaneous transmission in both directions. For this reason, there are no dedicated transmit and receive pairs, and consequently, crossover cables are never required for 1000BASE-T communication. The physical medium attachment sublayer (PMA) provides identification of each pair and usually continues to work even over cables where the pairs are unusually swapped or crossed

Assuming that with wireshark you see packets both ways on PC2 and NOT on PC1, and without further details on the hardware in use, my best guess is B). I hope this helps.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .