What's new in 5.1
=================

General
-------
* all of the tuneables can now be set at any time, not just whilst disabled
  or prior to loading rules;

* group identifiers may now be a number or name (universal);

* man pages rewritten

* tunables can now be set via ipf.conf;

Logging
-------
* ipmon.conf can now be used to generate SNMPv1 and SNMPv2 traps using
  information from log entries from the kernel;

NAT changes
-----------
* DNS proxy for the kernel that can block queries based on domain names;        

* FTP proxy can be configured to limit data connections to one or many
  connections per client;

* NAT on IPv6 is now supported;

* rewrite command allows changing both the source and destination address
  in a single NAT rule;

* simple encapsulation can now be configured with ipnat.conf,

* TFTP proxy now included;

Packet Filtering
----------------
* acceptance of ICMP packets for "keep state" rules can be refined through
  the use of filtering rules;

* alternative form for writing rules using simple filtering expressions;

* CIPSO headers now recognised and analysed for filtering on DOI;

* comments can now be a part of a rule and loaded into the kernel and
  thus displayed with ipfstat;

* decapsulation rules allow filtering on inner headers, providing they
  are not encrypted;

* interface names, aside from that the packet is on, can be present in
  filter rules;

* internally now a single list of filter rules, there is no longer an
  IPv4 and IPv6 list;

* rules can now be added with an expiration time, allowing for their
  automatic removal after some period of time;

* single file, ipf.conf, can now be used for both IPv4 and IPv6 rules;

* stateful filtering now allows for limits to be placed on the number
  of distinct hosts allowed per rule;

Pools
-----
* addresses added to a pool via the command line (only!) can be given
  an expiration timeout;

* destination lists are a new type of address pool, primarily for use with
  NAT rdr rules, supporting newer algorithms for target selection;

* raw whois information saved to a file can be used to populate a pool;

Solaris
-------
* support for use in zones with exclusive IP instances fully supported.

Tools
-----
* use of matching expressions allows for refining what is displayed or
  flushed;