Please help - What do these commands mean and how do i fix them?

[spadez]

I keep getting messages like this in console:

Quote:Bad challenge for IP

and sometimes

Old challenge for IP

What does this mean and how do i stop it? It seems to be stopping people from joining my server and im very unhappy about it

James

[Drocona]

it doesnt stop ppl from joining.
It's when the server receives an old HL1 query.
Can't be stopped, does nothing.