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Some ports have historically been associated with security vulnerabilities, but see little legitimate use on a WAN or the general Internet. They present a risk to your network and little to no legitimate use is prevented by blocking them. If your network is partitioned with one or more firewalls so that different parts support different functions or groups of users, you should consider applying the same restrictions at the firewalls between them.

As the listed abuse contact for much of the IP address space in use on Janet, Janet CSIRT receives many copyright infringement reports on behalf of the Janet community. Janet CSIRT is not able to identify individual users or machines on its customer organisations’ networks, so the most effective way to deal with these complaints of unacceptable use of the network is to forward them to the responsible customer organisation. Those organisations are required by the Janet AUP to deal effectively with complaints.

Why? To trace use of Janet, both legitimate and otherwise, helping to investigate and learn from security incidents. Whilst some network events are of a continuing nature, others may only occur sporadically and unexpectedly, and logging of activity can help us understand what took place in the past. Many networks now use Network Address Translation (NAT) or proxy devices that obscure the source of of a connection to the external world, which can prevent the timely investigation of serious incidents.

Typical Denial of Service abuse (DoS) involves a very large number of connections or packets being directed to the target computer, either from a single source IP address or (Distributed Denial of Service, DDoS) from a number of addresses, possibly a large number and probably in several different networks. Sometimes the effect is to stop the data network working or make it so slow as to interfere with its normal use; sometimes the target is a single machine which also may cease to work or run very slowly.