On Wed, 13 Aug 2014, Sean Dennis wrote to All:

 SD> Do any of you sysops have problems with callers from sdf.org? 

in what manner?

IIRC, sdf allows telnet chaining where one can come in from one system and
telnet out to another and keep doing that until they reach their
destination... some years back it was done be certain individuals intent on
causing problems and many systems adjusted to prevent the abuse from being
to be passed on from their systems...

what you might also be seeing is certain systems checking if your system is
up and responding to connections for their live updated bbs listing... i've
found a couple of systems doing that without asking and if it hs gotten to
be too much, i've simply blocked their IP at my perimeter... in some cases
a permanent block in my ipdrop section and others simply a managed timed
block which expires some time after the last offense...

)\/(ark