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Many years ago I set up a network of 4 Linux machines running RHEL 5. At the time it all seemed straight-forward. However, over the last few years, most of my work has required Windows. When I attach a Windows 7 or 10 machine to the network, everything just works. I now have project where the program only runs on Linux. So I installed Kubuntu 18.04 from a live image. Nothing related to networking functions and the messages I get make so little sense I have not been able to google a solution.

To start, all the machines are part of the domain td-research.com. The netmask is 255.255.255.0, I created an /etc/hosts file on the new machine and assigned it 172.24.2.65. The internal address of the modem that acts as the dns server is 172.24.2.2. Everything is hard-wired.

I then went to Configure Network Settings

Some of the terminology is not completely clear to me, but the settings I used were:

Method: Manual DNS Servers: 172.24.2.2,8.8.8.8 Search Domains: td-research.com Address: 172.24.2.65 Netmask: 255.255.255.0 Gateway: 172.24.2.1

and required IPv4, just to try and get this started.

I can ping vesta and it says it is pinging 172.24.2.70, which is correct from the hosts file.

I am not sure I believe it. If I rlogin -4 vesta it says the vesta is not recognized and asked me if I want to connect. When I say yes, it says it connected, but 'hostname' returns themis- the LOCAL computer and using ls, it is clear that it logged into itself, not another computer.

resolv.conf has the search field for the domain, but it does not list the nameservers that I thought I setup earlier. The /etc/network/interfaces has nothing in it except the loopback interface. But ifconfig shows inet 172.24.2.65 netmask 255.255.255.0 broadcast 172.24.2.255. A netstat -r shows 172.24.2.0 as a destination with a gateway of 0.0.0.0 and a Genmask of 255.255.255.0.

I cannot rlogin or ssh from vesta to themis either, I just get host unreachable.

Most of the google hits refer to performing operations that no longer work or involve commands that don't exist.

Could any one suggest what to do in terms of debugging this or tutorial that actually explains the whys of the steps and is not just a bunch of magic commands to type? Or are there pieces of kubuntu that need to be installed?

I already installed net-tools and the ssh-server.

I do notice that when it 'connects' it says last login from 127.0.0.1 and not last login from 172.24.2.65. Whereas if I log in from vesta to one of my other RHEL machines, I'll see last login from vesta as the message.

If I look in resolv.conf I see a nameserver 127.0.0.53. I saw something that said that sudo systemctl disable systemd-resolved would remove that and fix my problem. When I rebooted, the network would not connect until I unchecked IPv4 is required. And even then FireFox stopped working-

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  • "f I rlogin -4 vesta it says the vesta is not recognized and asked me if I want to connect." - what is the message, exactly? If it's a name resolution failure, rlogin should exit with Could not resolve hostname vesta: Name or service not known Dec 29, 2018 at 18:06
  • Unfortunately, it asks once and then adds something to some configuration file. Here is the message: The authenticity of host 'vesta (127.24.2.70) can't be established. ECDSA key fingerprint is [big number]. Are you sure you want to continue? And if yes something gets updated somewhere and I don't see the message again. Dec 29, 2018 at 18:24
  • Warning permanantly adding 'vesta' (ECDSA) to the list of known hosts. Though vesta is in /etc/hosts. Dec 29, 2018 at 18:28
  • That's completely normal, and nothing to do with /etc/hosts - it's just a way for SSH to flag possible MITM attacks - see for example The authenticity of host '103.35.202.76 (103.32.202.71)' can't be established Dec 29, 2018 at 18:35
  • yes, I didn't think that was my problem. However, when I rlogin vesta from themis and themis logs into itself instead, that is a problem. Dec 29, 2018 at 18:38

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Sorry everyone, it was my fault. There was a typo in the /etc/hosts file and I did not see it. Once I fixed it, the problem went away! I think if the rlogin had failed, I would have caught it faster.

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