As in if I only want 20-23a to connect how do I do that?

you don't, in other words tell your server list that  the server is for that protocol version.

Unless 20-23a implements unique network behavior compared to other versions, this is impossible

12 hours ago, Goodly said:

Unless 20-23a implements unique network behavior compared to other versions, this is impossible

????? MCGalaxy since 1.9.3.5 supports protocol versions 3-7

13 hours ago, icanttellyou said:

????? MCGalaxy since 1.9.3.5 supports protocol versions 3-7

You're right, I forgot that the client actually sends different protocol versions. I was thinking about how classic versions didn't send an AppName, but that's not needed to tell the difference in this case.

So basically it is possible, with a simple plugin. You can copy the KickNoCC plugin and modify it so that instead of checking p.appName, it can check if (p.ProtocolVersion != Server.VERSION_0020) then p.Leave and set p.cancellogin to true

5 hours ago, Goodly said:

You're right, I forgot that the client actually sends different protocol versions. I was thinking about how classic versions didn't send an AppName, but that's not needed to tell the difference in this case.

So basically it is possible, with a simple plugin. You can copy the KickNoCC plugin and modify it so that instead of checking p.appName, it can check if (p.ProtocolVersion != VERSION_0020) then p.Leave and set p.cancellogin to true

so what is each protocol number then?

7 hours ago, Hedwig7s said:

so what is each protocol number then?

Check here for a description of all of them. Also, I forgot that you have to include Server. before the VERSION_0020 in my hypothetical plugin. like

if (p.ProtocolVersion != Server.VERSION_0020)

 

22 hours ago, Goodly said:

Check here for a description of all of them. Also, I forgot that you have to include Server. before the VERSION_0020 in my hypothetical plugin. like

if (p.ProtocolVersion != Server.VERSION_0020)

 

Thanks might update my servers like Generic since it seems less resource intensive