I've been getting a "Disconnecting Player" error when none of my users are connected or attempting to connect....?

Hello all

I've been running a server with about 80 mods since December. Server works great, no issues there (other than a few issues with MovingWorlds and the Davinci's Vessels mod, but that's neither here nor there). But over the past few days, I've started receiving these errors (in groups of 4) when none of my players are connected or attempting to connect.

[09:36:29] [Netty Epoll Server IO #5/INFO] [FML]: Disconnecting Player: This server has mods that require FML/Forge to be installed on the client: [Antique Atlas, Applied Energistics 2, Arcane Essentials, Atum 2, BQ Forestry Expansion, Baubles, Better Questing, Better Questing Quest Book, BiblioCraft, Biomes O' Plenty, Blood Magic: Alchemical Wizardry, Bloody Quests, BuildCraft, BuildCraft Builders, BuildCraft Compat, BuildCraft Energy, BuildCraft Factory, BuildCraft Lib, BuildCraft Robotics, BuildCraft Silicon, BuildCraft Transport, Chisel, CoFH Core, CodeChicken Lib, Davinci's Vessels, Defiled Lands, Dimensional Doors, DrZhark's CustomSpawner, DrZhark's Mo'Creatures Mod, Electroblob's Wizardry, Extra Utilities 2, Forestry, Galacticraft Core, Galacticraft Planets, Guide-API, IndustrialCraft 2, Infernal Mobs, Iron Chest, LLibrary, Mantle, Mekanism, Meldexun's Extra Spells, Moving World, Mowzie's Mobs, OpenBlocks, OpenModsLib, Patchouli, Progressive Bosses, Recurrent Complex, Redstone Flux, Standard Expansion, Thaumcraft, The Twilight Forest, Thermal Cultivation, Thermal Dynamics, Thermal Expansion, Thermal Foundation, Tinkers' Construct, Underground Biomes, YABBA]
[09:36:29] [Netty Epoll Server IO #6/INFO] [FML]: Disconnecting Player: This server has mods that require FML/Forge to be installed on the client: [Antique Atlas, Applied Energistics 2, Arcane Essentials, Atum 2, BQ Forestry Expansion, Baubles, Better Questing, Better Questing Quest Book, BiblioCraft, Biomes O' Plenty, Blood Magic: Alchemical Wizardry, Bloody Quests, BuildCraft, BuildCraft Builders, BuildCraft Compat, BuildCraft Energy, BuildCraft Factory, BuildCraft Lib, BuildCraft Robotics, BuildCraft Silicon, BuildCraft Transport, Chisel, CoFH Core, CodeChicken Lib, Davinci's Vessels, Defiled Lands, Dimensional Doors, DrZhark's CustomSpawner, DrZhark's Mo'Creatures Mod, Electroblob's Wizardry, Extra Utilities 2, Forestry, Galacticraft Core, Galacticraft Planets, Guide-API, IndustrialCraft 2, Infernal Mobs, Iron Chest, LLibrary, Mantle, Mekanism, Meldexun's Extra Spells, Moving World, Mowzie's Mobs, OpenBlocks, OpenModsLib, Patchouli, Progressive Bosses, Recurrent Complex, Redstone Flux, Standard Expansion, Thaumcraft, The Twilight Forest, Thermal Cultivation, Thermal Dynamics, Thermal Expansion, Thermal Foundation, Tinkers' Construct, Underground Biomes, YABBA]
[09:36:29] [Netty Epoll Server IO #7/INFO] [FML]: Disconnecting Player: This server has mods that require FML/Forge to be installed on the client: [Antique Atlas, Applied Energistics 2, Arcane Essentials, Atum 2, BQ Forestry Expansion, Baubles, Better Questing, Better Questing Quest Book, BiblioCraft, Biomes O' Plenty, Blood Magic: Alchemical Wizardry, Bloody Quests, BuildCraft, BuildCraft Builders, BuildCraft Compat, BuildCraft Energy, BuildCraft Factory, BuildCraft Lib, BuildCraft Robotics, BuildCraft Silicon, BuildCraft Transport, Chisel, CoFH Core, CodeChicken Lib, Davinci's Vessels, Defiled Lands, Dimensional Doors, DrZhark's CustomSpawner, DrZhark's Mo'Creatures Mod, Electroblob's Wizardry, Extra Utilities 2, Forestry, Galacticraft Core, Galacticraft Planets, Guide-API, IndustrialCraft 2, Infernal Mobs, Iron Chest, LLibrary, Mantle, Mekanism, Meldexun's Extra Spells, Moving World, Mowzie's Mobs, OpenBlocks, OpenModsLib, Patchouli, Progressive Bosses, Recurrent Complex, Redstone Flux, Standard Expansion, Thaumcraft, The Twilight Forest, Thermal Cultivation, Thermal Dynamics, Thermal Expansion, Thermal Foundation, Tinkers' Construct, Underground Biomes, YABBA]
[09:36:29] [Netty Epoll Server IO #0/INFO] [FML]: Disconnecting Player: This server has mods that require FML/Forge to be installed on the client: [Antique Atlas, Applied Energistics 2, Arcane Essentials, Atum 2, BQ Forestry Expansion, Baubles, Better Questing, Better Questing Quest Book, BiblioCraft, Biomes O' Plenty, Blood Magic: Alchemical Wizardry, Bloody Quests, BuildCraft, BuildCraft Builders, BuildCraft Compat, BuildCraft Energy, BuildCraft Factory, BuildCraft Lib, BuildCraft Robotics, BuildCraft Silicon, BuildCraft Transport, Chisel, CoFH Core, CodeChicken Lib, Davinci's Vessels, Defiled Lands, Dimensional Doors, DrZhark's CustomSpawner, DrZhark's Mo'Creatures Mod, Electroblob's Wizardry, Extra Utilities 2, Forestry, Galacticraft Core, Galacticraft Planets, Guide-API, IndustrialCraft 2, Infernal Mobs, Iron Chest, LLibrary, Mantle, Mekanism, Meldexun's Extra Spells, Moving World, Mowzie's Mobs, OpenBlocks, OpenModsLib, Patchouli, Progressive Bosses, Recurrent Complex, Redstone Flux, Standard Expansion, Thaumcraft, The Twilight Forest, Thermal Cultivation, Thermal Dynamics, Thermal Expansion, Thermal Foundation, Tinkers' Construct, Underground Biomes, YABBA]

This is the second time in the past few days. It appears to be someone attempting to connect without the required group of mods installed. But all of my users (all 3 of them, including myself) are up to date. We are running version 1.12.2 of Minecraft (which I understand is no longer supported) but nothing regarding the server has changed in the past week or so. No other errors or even warnings. The timing of the attempted connections is a bit suspect as well (appearing to happen all at the same time).

Is this a potential network security issue? The timing of the connections would lead me to believe that someone is pinging my server. I don't believe this is a bug (I haven't seen it up until a day or so ago) which is why I am posting it in this board.

Anyone else run into something like this?