Multicast – IGMP Snooping and IGMP Querier – Sender and Reciever(s) in same VLAN/Layer 2 Segment

Multicast is a networking method used to efficiently transmit data to multiple recipients simultaneously. Unlike unicast (one-to-one) and broadcast (one-to-all) communication, multicast is a one-to-many or many-to-many method where data is sent only to devices that are interested in receiving it, rather than to all devices on a network. In multicast, devices that want to … Read more

Install VMware PowerCLI

You can install VMware PowerCLI via either the online installer, i.e direct into PowerShell, or via an offline installer. The offline installer instructions can be found here. For online installation, you can perform the following steps: Step 1 – Open PowerShell, you may need to “Run as Administrator”. Step 2 – Install all PowerCLI modules … Read more

SSH Legacy Key Algorithms

Sometimes you have some kit that is just old and isn’t supporting the recent (and secure) key algorithms. If you connect from a client without the correct set of ciphers available, so the client and the server can come to some agreement on a mutually supported cipher set, you’ll see an error such as: If … Read more

AWS Transit Gateway with VPN to On-Premise Palo Alto Firewall

The AWS Transit Gateway can be used to join the networking of many VPCs (in the same or different AWS Accounts) within the same region together to facilitate communication, it may also be used in conjunction with DX (Direct Connect) or Site-to-Site VPNs to provide connectivity to other Cloud Platforms but additionally to on-premise networks … Read more

VMware vCenter – “Exception in invoking authentication handler User password expired”

An appliance that was deployed over 90 days old with no changes made to the default settings. When attempting to logon to the VAMI console of the appliance i.e. https://vcenter.domain.com:5480 you get the message: “Exception in invoking authentication handler User password expired”. To resolve this you need to reset the password, then set it not … Read more

Active Directory Read Only Domain Controller (RODC) – “there are currently no logon servers available to service the logon request”

We had an issue where our RODCs suddenly stopped authenticating users and also would not allow administrators to logon via RDP or locally via the console giving this message: “there are currently no logon servers available to service the logon request” Any downstream services that were trying to authenticate via LDAP or LDAPS also failed … Read more