diff options
author | Simon L. B. Nielsen <simon@FreeBSD.org> | 2005-03-31 21:11:56 +0000 |
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committer | Simon L. B. Nielsen <simon@FreeBSD.org> | 2005-03-31 21:11:56 +0000 |
commit | bac2a185c28eb545bb62b601ab14d056db4fdafe (patch) | |
tree | 64f1eae1c10e6c2afabdf9162926323673809139 | |
parent | e3b704a49c37183039c629091cb72d32889ca7c6 (diff) |
Notes
-rw-r--r-- | en_US.ISO8859-1/books/handbook/firewalls/chapter.sgml | 71 |
1 files changed, 27 insertions, 44 deletions
diff --git a/en_US.ISO8859-1/books/handbook/firewalls/chapter.sgml b/en_US.ISO8859-1/books/handbook/firewalls/chapter.sgml index df90abc8fa..962d5a92f5 100644 --- a/en_US.ISO8859-1/books/handbook/firewalls/chapter.sgml +++ b/en_US.ISO8859-1/books/handbook/firewalls/chapter.sgml @@ -141,59 +141,35 @@ </sect1> <sect1 id="firewalls-apps"> - <title>Firewall Software Applications</title> - - <para>&os; has three different firewall software products built - into the base system. They are IPFILTER (also known as IPF), - IPFIREWALL (also known as IPFW) and PF (OpenBSD's PacketFilter). - IPFIREWALL has the built in DUMMYNET traffic shaper facilities - for controlling bandwidth usage. IPFILTER does not have a built - in traffic shaper facility for controlling bandwidth usage, but - the ALTQ port application can be used to accomplish the same - function. The DUMMYNET feature and <acronym>ALTQ</acronym> is - generally useful only to large ISPs or commercial users. IPF, - IPFW and PF use rules to control the access of packets to and + <title>Firewall Packages</title> + + <para>&os; has three different firewall packages built + into the base system. They are: <emphasis>IPFILTER</emphasis> + (also known as <acronym>IPF</acronym>), + <emphasis>IPFIREWALL</emphasis> (also known as <acronym>IPFW</acronym>), + and <emphasis>OpenBSD's PacketFilter</emphasis> (also known as + <acronym>PF</acronym>). &os; also has two built in packages for + traffic shaping (basically controlling bandwidth usage): + &man.altq.4; and &man.dummynet.4;. Dummynet has traditionally been + closely tied with <acronym>IPFW</acronym>, and + <acronym>ALTQ</acronym> with + <acronym>IPF</acronym>/<acronym>PF</acronym>. IPF, + IPFW, and PF all use rules to control the access of packets to and from your system, although they go about it different ways and have different rule syntaxes.</para> - <!-- XXX: Is rc.firewall really outdated and complicated? - AND: should we modify/remove /etc/rc.firewall or rewrite - this: --> - - <para>The IPFW sample rule set (found in - <filename>/etc/rc.firewall</filename>) delivered in the basic - install is outdated, complicated and does not use stateful rules - on the interface facing the public Internet. It exclusively uses - legacy stateless rules which only have the ability to open or - close the service ports. The IPFW example stateful rules sets - presented here supercede the - <filename>/etc/rc.firewall</filename> file distributed with the - system.</para> - - <para>Stateful rules have technically advanced interrogation - abilities capable of defending against the flood of different - methods currently employed by attackers.</para> - - <para>All of these firewall software solutions IPF, IPFW and PF - still maintain their legacy heritage of their original rule - processing order and reliance on non-stateful rules. These - outdated concepts are not covered here, only the new, modern - stateful rule construct and rule processing order is - presented.</para> - - <para>You should read about both of them and make your own decision - on which one best fits your needs.</para> + <para>The reason that &os; has multiple build in firewall packages + is that different people have different requirements and + preferences. No single firewall package is the best.</para> <para>The author prefers IPFILTER because its stateful rules are much less complicated to use in a <acronym>NAT</acronym> environment and it has a built in ftp proxy that simplifies the - rules to allow secure outbound FTP usage. It is also more - appropriate to the knowledge level of the inexperienced firewall - user.</para> + rules to allow secure outbound FTP usage.</para> - <para>Since all firewalls are based on interrogating the values of + <para>Since all firewalls are based on inspecting the values of selected packet control fields, the creator of the firewall - rules must have an understanding of how + rulesets must have an understanding of how <acronym>TCP</acronym>/IP works, what the different values in the packet control fields are and how these values are used in a normal session conversation. For a good explanation go to: @@ -2104,6 +2080,13 @@ pass in quick on rl0 proto tcp from any to any port = 20 flags S keep state</pro coding technique to achieve what is referred to as Simple Stateful logic.</para> + <para>The IPFW sample rule set (found in + <filename>/etc/rc.firewall</filename>) in the standard &os; + install is rather simple and it is not expected that it used + directly without modifications. The example does not use + stateful filtering, which is beneficial in most setups, so it + will not be used as base for this section.</para> + <para>The IPFW stateless rule syntax is empowered with technically sophisticated selection capabilities which far surpasses the knowledge level of the customary firewall installer. IPFW is |