This information track document is now published as GFD-I.083. You can download it here: http://www.ggf.org/gf/docs/?final Title: Firewall Issues overview Authors/editors: Ralph Niederberger, William Allcock, Leon Gommans, Egon Grünter, Thijs Metsch, Inder Monga, Gian Luca Volpato, Christian Grimm. Abstract Several kinds of network devices like Firewalls are used to protect an institutional network against malicious attacks from the public Internet. This document enumerates and illustrates a selected set of grid scenarios that encounter some issues when dealing with firewall types of devices. The knowledge and experience gathered through these use-cases is utilized to classify the issues into homogeneous categories that can be used by grid application developers and management personnel as guidance. These categories will be used to propose new or recommend existing academic and/or standards based solutions to the grid community.