I'd like to apologize to fedgar for the excessive drama used in my original post, causing it to be taken in a way which was not intended, please allow me to rephrase this a bit:
congratulations on a successful migration to new server software.
With all the new goings on I have not seen everything new yet. I did however discover, to my disappointment, skyblock nether portals are now private.
I hope this was merely an oversight and not the intended behavior as many of us in skyblock use the nether as a means of inter-island travel. Given this situation we are left with only warp signs as a means of getting around. It is my genuine hope, change to this policy is considered, thank you.
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anyway, as for unwanted visitors, I count myself among those that really don't want random people wandering my island. I totally get that, and that is why my portal is in my shop and a piston door separates my shop from the rest of the island. I will gladly share my circuitry with anyone interested in using it as a security measure for their own portals, but even the humble wooden door cannot be opened by anyone that is not a member of the island it's on or the admin group.
I don't think I've used the '/is kick' or '/is ban' commands yet, unsure if they're only for use on only island members or anyone on the island, but in the case of the latter, would this not be effective enough? I don't know how this one works just thinking out loud here.