Point to Point Connection Between Two Hosts
Ensure that at least one of the Ethernet ports is GigE. Otherwise you might need a crossover cable.
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THE DOCTOR
I am a Time-Lord from the planet Gallifrey and the last remaining survivor of my race. I have regenerated several times now as follows: Database Developer -> QA Engineer -> Software Engineer -> Network/Systems Engineer -> Director of IT & Network Engineering.
Updated on September 18, 2022Comments
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THE DOCTOR over 1 year
I am trying to set up a point to point connection between two Linux host machines. I've connected both of them with crossover cable, but they can't ping each other. Here are the configurations for each laptop:
Laptop 1
(eth0 configuration) IP Address - 128.110.1.6 Subnet Mask - 255.255.255.240 Gateway - 128.110.1.1
Laptop 2
(eth0 configuration) IP address - 128.110.1.1 Subnet Mask - 255.255.255.240 Gateway - 128.110.1.6
Is there something that I'm missing here? How can I establish connectivity between the two laptops?
Edit-1: I ran the
'arp -a'
command and received the following output:Laptop 1
? (128.110.1.1) at <incomplete> on eth0
Laptop 2
? (128.110.1.6) at <incomplete> on eth0
I'm guessing these entries in the ARP table might be due to the failed pings.
Edit-2: I discovered that one of the laptops has a bridge enabled which was previously used with a usb-to-ethernet adapter interface as
eth1
and the built in ethernet interface iseth0
. Not sure if that would affect anything though. Following the suggestion to runethtool
produced the following output:Laptop 1
[root@link_3 doctor]# /sbin/ethtool eth0 Settings for eth0: Link detected: yes [root@link_3 doctor]# /sbin/ethtool eth1 Settings for eth1: Supported ports: [ TP MII ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Supports auto-negotiation: Yes Advertised link modes: Not reported Advertised auto-negotiation: No Speed: 10Mb/s Duplex: Half Port: Twisted Pair PHYAD: 0 Transceiver: internal Auto-negotiation: on Link detected: no
Laptop 2
[root@hitl3 doctor]# /sbin/ethtool eth0 Settings for eth0: Supported ports: [ MII ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Half 1000baseT/Full Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Half 1000baseT/Full Advertised auto-negotiation: Yes Speed: 1000Mb/s Duplex: Full Port: Twisted Pair PHYAD: 1 Transceiver: internal Auto-negotiation: on Supports Wake-on: g Wake-on: d Current message level: 0x000000ff (255) Link detected: yes
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MadHatter over 10 yearsSorry to ask stupid questions, but I take it that neither box is running a firewall (
iptables -L -n -v
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Renan over 10 yearsis the link on the network card detected? what about the speed they are working at? you can check with
ethtool <ethX>
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THE DOCTOR over 10 years@MadHatter - Firewall and SELinux are both disabled and there's nothing in the iptables.
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Admin over 10 yearsThe ethtool suggestion was a good one. Let's see the result. And the received packet count from
ifconfig
- whether or not it goes up while you're attempting a ping would be interesting. -
hookenz over 10 yearsYou don't need to define the gateway address as the other machine. That's not really right but won't prevent it working. On Laptop 1 set the ethernet configuration to eth0 since eth1 doesn't have a link but eth0 does.
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Admin over 10 yearsThe first ethtool just prints those 2 lines of output? That's really odd. What driver is running that eth0? And does ethtool report that the link goes down if you unplug the cable?
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Admin over 10 yearsDo you have ping enabled and are the cards giving led status orange/green both?
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Renan over 10 yearsI find it odd that laptop detected a link at 1Gbps while the other card only supports 100Mbps, though I don't remember what should happen in this case. What happens if you use
ethtool -s eth0 speed 100 duplex full
on laptop 2?
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THE DOCTOR over 10 yearsActually, I am using a crossover cable. I updated my question to mention that.
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symcbean over 10 yearsDoes it work? Do the systems connect when you use patch cables and a hub?