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authorSimon L. B. Nielsen <simon@FreeBSD.org>2005-03-31 21:11:56 +0000
committerSimon L. B. Nielsen <simon@FreeBSD.org>2005-03-31 21:11:56 +0000
commitbac2a185c28eb545bb62b601ab14d056db4fdafe (patch)
tree64f1eae1c10e6c2afabdf9162926323673809139
parente3b704a49c37183039c629091cb72d32889ca7c6 (diff)
Notes
-rw-r--r--en_US.ISO8859-1/books/handbook/firewalls/chapter.sgml71
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!-- XXX: Is rc.firewall really outdated and complicated?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