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Of course, every release of an linux-distribution has to change the way very basic network settings are configured. 😉 Ubuntu 20.04 Server LTS to be fair: „netplan“ has been in place since at least release 17.10 the „subiquity“-tool which has written the yaml-file has been confusing me… Step 1: Figure out – which IP/DNS-Settings where set by DHCP Step 2: Disable (if required) automation tools – here „subiquity“ This is YAML: Optional: Try a temporarily YAML-File before Apply safeguard if you are using a ssh-connection Roll back, after a Timeout Step 3: Edit/Apply NetPlan Config ApplyRead More →

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more than ten years later (IEEE 802.1ax-2008), but everybody calls it 802.3ad and serverguys still prefer static bonding with round-robin distribution [without telling network admins about that decision] to confuse (or tear down) ethernet-networks. What a stupid default: default bond0 interface with balance round robin mode Awsome 🙂 FWM-2-STM_LOOP_DETECT How a single server affects vMotion, SLB-VIP-Mobility, First-Hop Redundancy-Protocols (VRRP, HSRP you name it) in 2019. I won’t expect technology like software-defined-networks to solve human ignorance.Read More →

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It’s a two step process to get rid of insecure username/password-authentication. Generate a RSA keypair at your SSH-client btw. Cisco-IOS doesn’t support DSA-keys Configure your network device(s) to assign the (public-)key of this keypair to an user-account This user-account could get privileges from a Radius/TACACS+-Server which could provide access-logs, too. Generate RSA-Key: Windows as SSH-Client I prefer Putty, usually in form of „mRemoteNG“, so i use PuttyGen to generate the RSA keypair. Windows.Start => PuttyGen (x) RSA, 4096-bits are supported, use it [Generate] move the mouse to improve the randomgenerator change the „comment“ – for example replace it by an username add a passphrase –Read More →

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Background: Python-Requests wants to verify https-certificates, which makes sense to me. – but my VCenter uses a self-signed Certificate Don’t think about ignoring certificate errors 😉 Prerequisites Download the certificate from the VCenter: Install the certificate: Now Python.requests validates the vCenter: Add the Export to ~/.bashrc at the end of the fileRead More →

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…this article should have been published at 2017-11-23, i forgot to press the right botton. So, an update might be needed, anyone still interested in cot today? Release 2.1 (2018-01-29) is the current release, containing some fixes (https://github.com/glennmatthews/cot/blob/master/CHANGELOG.rst) COT installation using PIP So, let’s go, following thats embarassing. Install PIP first Try it again Optional: Argument-Completion Not essential, but handy. COT helpers A full installation requires so called „cot-helpers“ to use all features. first fix „fatdisk“ which is used to inject configs into OVA-Files uncomment to and run the helper-installation again: But it threw a lot of warnings.. warning: format ‘%lu’ expects argument of typeRead More →

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A new linux-VM takes ages to boot: it waits for 2 minutes for the network to come up Whats the reason for the delay? „routable“ interfaces with not router-address provided by the dhcp-service never come up for the „networkd-wait-online“-service. find more information at GitHub Issue 3752 – systemd-networkd can’t configure interface if dhcp server does not provide routers State: forever „configuring“ not „configured“ Background information „enp0s3“ is a virtual-box „host-only“ network with no routing provided Action Plan: „Set this interface to not be checked.“ locate the systemd-unit-file: Path: /run/systemd/generator/network-online.target.wants File: systemd-networkd-wait-online.service Edit (sudo) file add „ignore“-Option docs: networkd wait online service The service specific configurationRead More →

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It should be easy, and it is – but no single-command installation: Look at the Ubuntu Packet-Search for Ansible: it’s in the „universe“-repository Add the „universe“-repository: Now it works: Which version? as „packages.ubuntu.com“ said: 2.5.1Read More →