1 | <?xml version="1.0" encoding="ISO-8859-1"?>
|
---|
2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
|
---|
3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
|
---|
4 | <!ENTITY % general-entities SYSTEM "../../general.ent">
|
---|
5 | %general-entities;
|
---|
6 |
|
---|
7 | <!ENTITY nftables-download-http "https://netfilter.org/projects/nftables/files/nftables-&nftables-version;.tar.bz2">
|
---|
8 | <!ENTITY nftables-download-ftp " ">
|
---|
9 | <!ENTITY nftables-md5sum "9913b2b46864394d41916b74638e0875">
|
---|
10 | <!ENTITY nftables-size "772 KB">
|
---|
11 | <!ENTITY nftables-buildsize "34 MB">
|
---|
12 | <!ENTITY nftables-time "0.2 SBU">
|
---|
13 | ]>
|
---|
14 |
|
---|
15 | <sect1 id="nftables" xreflabel="nftables-&nftables-version;">
|
---|
16 | <?dbhtml filename="nftables.html"?>
|
---|
17 |
|
---|
18 |
|
---|
19 | <title>nftables-&nftables-version;</title>
|
---|
20 |
|
---|
21 | <indexterm zone="nftables">
|
---|
22 | <primary sortas="a-nftables">nftables</primary>
|
---|
23 | </indexterm>
|
---|
24 |
|
---|
25 | <sect2 role="package">
|
---|
26 | <title>Introduction to nftables</title>
|
---|
27 |
|
---|
28 | <para>
|
---|
29 | The <application>nftables</application> package, intended to be the
|
---|
30 | successor to <xref linkend="iptables"/>, provides a low-level netlink
|
---|
31 | programming interface (API), and userspace uitlities for the in-kernel
|
---|
32 | nf_tables subsystem.
|
---|
33 | </para>
|
---|
34 |
|
---|
35 | &lfs90_checked;
|
---|
36 |
|
---|
37 | <bridgehead renderas="sect3">Package Information</bridgehead>
|
---|
38 | <itemizedlist spacing='compact'>
|
---|
39 | <listitem>
|
---|
40 | <para>
|
---|
41 | Download (HTTP): <ulink url="&nftables-download-http;"/>
|
---|
42 | </para>
|
---|
43 | </listitem>
|
---|
44 | <listitem>
|
---|
45 | <para>
|
---|
46 | Download (FTP): <ulink url="&nftables-download-ftp;"/>
|
---|
47 | </para>
|
---|
48 | </listitem>
|
---|
49 | <listitem>
|
---|
50 | <para>
|
---|
51 | Download MD5 sum: &nftables-md5sum;
|
---|
52 | </para>
|
---|
53 | </listitem>
|
---|
54 | <listitem>
|
---|
55 | <para>
|
---|
56 | Download size: &nftables-size;
|
---|
57 | </para>
|
---|
58 | </listitem>
|
---|
59 | <listitem>
|
---|
60 | <para>
|
---|
61 | Estimated disk space required: &nftables-buildsize;
|
---|
62 | </para>
|
---|
63 | </listitem>
|
---|
64 | <listitem>
|
---|
65 | <para>
|
---|
66 | Estimated build time: &nftables-time;
|
---|
67 | </para>
|
---|
68 | </listitem>
|
---|
69 | </itemizedlist>
|
---|
70 |
|
---|
71 | <bridgehead renderas="sect3">nftables Dependencies</bridgehead>
|
---|
72 |
|
---|
73 | <bridgehead renderas="sect4">Required</bridgehead>
|
---|
74 | <para role="required">
|
---|
75 | <xref linkend="libnftnl"/>
|
---|
76 | </para>
|
---|
77 |
|
---|
78 | <bridgehead renderas="sect4">Recommended</bridgehead>
|
---|
79 | <para role="recommended">
|
---|
80 | <xref linkend="jansson"/> (for JSON rules table support)
|
---|
81 | </para>
|
---|
82 |
|
---|
83 | <bridgehead renderas="sect4">Optional</bridgehead>
|
---|
84 | <para role="optional">
|
---|
85 | <xref linkend="iptables"/> and
|
---|
86 | <xref linkend="docbook-utils"/>
|
---|
87 | </para>
|
---|
88 |
|
---|
89 | <bridgehead renderas="sect4">Optional (runtime)</bridgehead>
|
---|
90 |
|
---|
91 | <para role="optional">
|
---|
92 | <ulink url="https://netfilter.org/projects/conntrack-tools/index.html">
|
---|
93 | contrack-tools</ulink>
|
---|
94 | <ulink url="https://netfilter.org/projects/nfacct/index.html">
|
---|
95 | nfacct</ulink>
|
---|
96 | <ulink url="https://netfilter.org/projects/ulogd/index.html">
|
---|
97 | ulogd</ulink>
|
---|
98 | </para>
|
---|
99 |
|
---|
100 | <para condition="html" role="usernotes">User Notes:
|
---|
101 | <ulink url="&blfs-wiki;/nftables"/>
|
---|
102 | </para>
|
---|
103 | </sect2>
|
---|
104 |
|
---|
105 | <sect2 role="kernel">
|
---|
106 | <title>Kernel Configuration</title>
|
---|
107 |
|
---|
108 | <para>
|
---|
109 | Enable the following options in the kernel configuration and recompile the
|
---|
110 | kernel if necessary (add any additional nf_tables features as needed):
|
---|
111 | </para>
|
---|
112 |
|
---|
113 | <screen><literal>[*] Networking support [CONFIG_NET] --->
|
---|
114 | Networking options --->
|
---|
115 | [*] Network packet filtering framework (Netfilter) [CONFIG_NETFILTER] --->
|
---|
116 | Core Netfilter Configuration --->
|
---|
117 | <*> * protocol support [CONFIG_NF_CONNTRACK_*]
|
---|
118 | <*> Netfilter nf_tables support [CONFIG_NF_TABLES]
|
---|
119 | [*] Netfilter nf_tables * support [CONFIG_NF_TABLES_*]</literal></screen>
|
---|
120 |
|
---|
121 | <para>
|
---|
122 | Include any connection tracking protocols that will be used, and
|
---|
123 | any protocols that you wish to use for match suppport under the
|
---|
124 | "Core Netfilter Configuration" section. Additionally, include any
|
---|
125 | "Netfilter nf_tables * module" that will be used under the
|
---|
126 | "Netfilter nf_tables support" section.
|
---|
127 | </para>
|
---|
128 |
|
---|
129 |
|
---|
130 | </sect2>
|
---|
131 |
|
---|
132 | <sect2 role="installation">
|
---|
133 | <title>Installation of nftables</title>
|
---|
134 |
|
---|
135 | <para>
|
---|
136 | Install <application>nftables</application> by running the following
|
---|
137 | commands:
|
---|
138 | </para>
|
---|
139 |
|
---|
140 | <screen><userinput>./configure --prefix=/usr \
|
---|
141 | --sbindir=/sbin \
|
---|
142 | --sysconfdir=/etc \
|
---|
143 | --with-json \
|
---|
144 | --with-python-bin=/usr/bin/python3 &&
|
---|
145 | make</userinput></screen>
|
---|
146 |
|
---|
147 | <para>
|
---|
148 | This package does not come with a test suite.
|
---|
149 | </para>
|
---|
150 |
|
---|
151 | <para>
|
---|
152 | Now, as the <systemitem class="username">root</systemitem> user:
|
---|
153 | </para>
|
---|
154 |
|
---|
155 | <screen role="root"><userinput>make install &&
|
---|
156 | mv /usr/lib/libnftables.so.* /lib &&
|
---|
157 | ln -sfv ../../lib/$(readlink /usr/lib/libnftables.so) /usr/lib/libnftables.so</userinput></screen>
|
---|
158 |
|
---|
159 | </sect2>
|
---|
160 |
|
---|
161 | <sect2 role="commands">
|
---|
162 | <title>Command Explanations</title>
|
---|
163 |
|
---|
164 | <!-- there is no disable-static option in the configure string
|
---|
165 | <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
|
---|
166 | href="../../xincludes/static-libraries.xml"/>
|
---|
167 | -->
|
---|
168 | <para>
|
---|
169 | <parameter>--with-json</parameter>: build with support for JSON rules.
|
---|
170 | Omit if <xref linkend="jansson"/> is not available.
|
---|
171 | </para>
|
---|
172 |
|
---|
173 | <para>
|
---|
174 | <parameter>--with-python-bin=/usr/bin/python3</parameter>: force use of
|
---|
175 | <application>Python3</application>.
|
---|
176 | </para>
|
---|
177 |
|
---|
178 | <para>
|
---|
179 | <option>--enable-man-doc</option>: build man pages if
|
---|
180 | <xref linkend="asciidoc"/> is installed (required if adding
|
---|
181 | json support).
|
---|
182 | </para>
|
---|
183 |
|
---|
184 | <para>
|
---|
185 | <option>--with-xtables</option>: build with
|
---|
186 | <xref linkend="iptables"/> libxtables support.
|
---|
187 | </para>
|
---|
188 |
|
---|
189 | <para>
|
---|
190 | <command>mv -v /usr/lib/nftables.so.* ...</command>: Move shared
|
---|
191 | libraries into /lib so they are available before /usr is mounted.
|
---|
192 | </para>
|
---|
193 |
|
---|
194 | </sect2>
|
---|
195 |
|
---|
196 | <sect2 role="configuration">
|
---|
197 | <title>Configuring nftables</title>
|
---|
198 |
|
---|
199 | <note>
|
---|
200 | <para>
|
---|
201 | If you intend to use <xref linkend="firewalld"/> to configure your
|
---|
202 | firewall rules, you should not use the example configuration provided
|
---|
203 | here, nor should you enable the
|
---|
204 | <phrase revision="sysv">bootscript.</phrase>
|
---|
205 | <phrase revision="systemd">systemd unit.</phrase>
|
---|
206 | </para>
|
---|
207 | </note>
|
---|
208 |
|
---|
209 | <sect3 id="fw-masqRouter-nft"
|
---|
210 | xreflabel="Creating a Masquerading Router With nftables">
|
---|
211 | <title>Masquerading Router</title>
|
---|
212 |
|
---|
213 | <para>
|
---|
214 | A network Firewall has two interfaces, one connected to an
|
---|
215 | intranet, in this example <emphasis role="strong">LAN1</emphasis>,
|
---|
216 | and one connected to the Internet, here <emphasis
|
---|
217 | role="strong">WAN1</emphasis>. You will need to adjust these value to
|
---|
218 | match your particular system. To provide the maximum security
|
---|
219 | for the firewall itself, make sure that there are no unnecessary
|
---|
220 | servers running on it such as <application>X11</application> et al.
|
---|
221 | As a general principle, the firewall itself should not access
|
---|
222 | any untrusted service (think of a remote server giving answers that
|
---|
223 | makes a daemon on your system crash, or even worse, that implements
|
---|
224 | a worm via a buffer-overflow).
|
---|
225 | </para>
|
---|
226 |
|
---|
227 | <note>
|
---|
228 | <para>
|
---|
229 | In the following example configuration, <emphasis
|
---|
230 | role="strong">LAN1</emphasis> is used for the internal LAN interface,
|
---|
231 | and <emphasis role="strong">WAN1</emphasis> is used for the external
|
---|
232 | interface connected to the Internet. You will need to replace these
|
---|
233 | values with appropriate interface names for your system.
|
---|
234 | </para>
|
---|
235 | </note>
|
---|
236 |
|
---|
237 |
|
---|
238 | <screen role="root"><?dbfo keep-together="auto"?><userinput>cat > /etc/nftables/nftables.conf << "EOF"
|
---|
239 | <literal>#!/sbin/nft -f
|
---|
240 |
|
---|
241 | # You're using the example configuration for a setup of a firewall
|
---|
242 | # from Beyond Linux From Scratch.
|
---|
243 | #
|
---|
244 | # This example is far from being complete, it is only meant
|
---|
245 | # to be a reference.
|
---|
246 | #
|
---|
247 | # Firewall security is a complex issue, that exceeds the scope
|
---|
248 | # of the configuration rules below.
|
---|
249 | #
|
---|
250 | # You can find additional information
|
---|
251 | # about firewalls in Chapter 4 of the BLFS book.
|
---|
252 | # https://www.&lfs-domainname;/blfs
|
---|
253 |
|
---|
254 | # Drop all existing rules
|
---|
255 | flush ruleset
|
---|
256 |
|
---|
257 | # Filter for both ip4 and ip6 (inet)
|
---|
258 | table inet filter {
|
---|
259 |
|
---|
260 | # filter incomming packets
|
---|
261 | chain input {
|
---|
262 |
|
---|
263 | # Drop everything that doesn't match policy
|
---|
264 | type filter hook input priority 0; policy drop;
|
---|
265 |
|
---|
266 | # accept packets for established connections
|
---|
267 | ct state { established, related } accept
|
---|
268 |
|
---|
269 | # Drop packets that have a connection state of invalid
|
---|
270 | ct state invalid drop
|
---|
271 |
|
---|
272 | # Allow connections to the loopback adapter
|
---|
273 | iifname "lo" accept
|
---|
274 |
|
---|
275 | # Allow connections to the LAN1 interface
|
---|
276 | iifname "LAN1" accept
|
---|
277 |
|
---|
278 | # Accept icmp requests
|
---|
279 | ip protocol icmp accept
|
---|
280 |
|
---|
281 | # Allow ssh connections on LAN1
|
---|
282 | iifname "LAN1" tcp dport ssh accept
|
---|
283 |
|
---|
284 | # Drop everything else
|
---|
285 | drop
|
---|
286 | }
|
---|
287 |
|
---|
288 | # Allow forwarding for external connections to WAN1
|
---|
289 | chain forward {
|
---|
290 |
|
---|
291 | # Drop if it doesn't match policy
|
---|
292 | type filter hook forward priority 0; policy drop;
|
---|
293 |
|
---|
294 | # Accept connections on WAN1
|
---|
295 | oifname "WAN1" accept
|
---|
296 |
|
---|
297 | # Allow forwarding to another host via this interface
|
---|
298 | # Uncomment the following line to allow connections
|
---|
299 | # ip daddr 192.168.0.2 ct status dnat accept
|
---|
300 |
|
---|
301 | # Allow established and related connections
|
---|
302 | iifname "WAN1" ct state { established, related } accept
|
---|
303 | }
|
---|
304 |
|
---|
305 | # Filter output traffic
|
---|
306 | chain output {
|
---|
307 |
|
---|
308 | # Allow everything outbound
|
---|
309 | type filter hook output priority 0; policy accept;
|
---|
310 | }
|
---|
311 | }
|
---|
312 |
|
---|
313 | # Allow NAT for ip protocol (both ip4 and ip6)
|
---|
314 | table ip nat {
|
---|
315 |
|
---|
316 | chain prerouting {
|
---|
317 |
|
---|
318 | # Accept on inbound interface for policy match
|
---|
319 | type nat hook prerouting priority 0; policy accept;
|
---|
320 |
|
---|
321 | # Accept http and https on 192.168.0.2
|
---|
322 | # Uncomment the following line to allow http and https
|
---|
323 | #iifname "WAN1" tcp dport { http, https } dnat to 192.168.0.2
|
---|
324 | }
|
---|
325 |
|
---|
326 | chain postrouting {
|
---|
327 |
|
---|
328 | # accept outbound
|
---|
329 | type nat hook postrouting priority 0; policy accept;
|
---|
330 |
|
---|
331 | # Masquerade on WAN1 outbound
|
---|
332 | oifname "WAN1" masquerade
|
---|
333 | }
|
---|
334 | }</literal>
|
---|
335 | EOF</userinput></screen>
|
---|
336 |
|
---|
337 | <para>
|
---|
338 | With this configuration your intranet should be reasonably secure
|
---|
339 | against external attacks. No one should be able to setup a new
|
---|
340 | connection to any internal service not configured above.
|
---|
341 | </para>
|
---|
342 |
|
---|
343 | <para>
|
---|
344 | There are several other examples in the
|
---|
345 | <filename class="directory">/etc/nftables</filename> directory.
|
---|
346 | </para>
|
---|
347 |
|
---|
348 | </sect3>
|
---|
349 |
|
---|
350 | <sect3 id="nftables-init">
|
---|
351 | <title><phrase revision="sysv">Boot Script</phrase>
|
---|
352 | <phrase revision="systemd">Systemd Unit</phrase></title>
|
---|
353 |
|
---|
354 | <para revision="sysv">
|
---|
355 | To set up the nftables firewall at boot, install the
|
---|
356 | <filename>/etc/rc.d/init.d/nftables</filename> init script included
|
---|
357 | in the <xref linkend="bootscripts"/> package.
|
---|
358 | </para>
|
---|
359 |
|
---|
360 | <para revision="systemd">
|
---|
361 | To set up the nftables firewall at boot, install the
|
---|
362 | <filename>nftables.service</filename> unit included in the
|
---|
363 | <xref linkend="systemd-units"/> package.
|
---|
364 | </para>
|
---|
365 |
|
---|
366 | <indexterm zone="nftables nftables-init">
|
---|
367 | <primary sortas="f-nftables">nftables</primary>
|
---|
368 | </indexterm>
|
---|
369 |
|
---|
370 | <screen role="root"><userinput>make install-nftables</userinput></screen>
|
---|
371 |
|
---|
372 | </sect3>
|
---|
373 |
|
---|
374 | </sect2>
|
---|
375 |
|
---|
376 | <sect2 role="content">
|
---|
377 | <title>Contents</title>
|
---|
378 |
|
---|
379 | <segmentedlist>
|
---|
380 | <segtitle>Installed Programs</segtitle>
|
---|
381 | <segtitle>Installed Libraries</segtitle>
|
---|
382 | <segtitle>Installed Directories</segtitle>
|
---|
383 |
|
---|
384 | <seglistitem>
|
---|
385 | <seg>
|
---|
386 | nft
|
---|
387 | </seg>
|
---|
388 | <seg>
|
---|
389 | libnftables.{a,so}
|
---|
390 | </seg>
|
---|
391 | <seg>
|
---|
392 | /etc/nftables
|
---|
393 | </seg>
|
---|
394 | </seglistitem>
|
---|
395 | </segmentedlist>
|
---|
396 |
|
---|
397 | <variablelist>
|
---|
398 | <bridgehead renderas="sect3">Short Descriptions</bridgehead>
|
---|
399 | <?dbfo list-presentation="list"?>
|
---|
400 | <?dbhtml list-presentation="table"?>
|
---|
401 |
|
---|
402 | <varlistentry id="nft">
|
---|
403 | <term><filename>nft</filename></term>
|
---|
404 | <listitem>
|
---|
405 | <para>
|
---|
406 | command line interface for the nf_tables subsystem.
|
---|
407 | </para>
|
---|
408 | <indexterm zone="nftables nft">
|
---|
409 | <primary sortas="a-nft">nft</primary>
|
---|
410 | </indexterm>
|
---|
411 | </listitem>
|
---|
412 | </varlistentry>
|
---|
413 |
|
---|
414 | <varlistentry id="libnftables">
|
---|
415 | <term><filename class="libraryfile">libnftables.{a,so}</filename></term>
|
---|
416 | <listitem>
|
---|
417 | <para>
|
---|
418 | provides functions for manipulating the nf_tables subsystem.
|
---|
419 | </para>
|
---|
420 | <indexterm zone="nftables libnftables">
|
---|
421 | <primary sortas="c-libnftables">libnftables.so</primary>
|
---|
422 | </indexterm>
|
---|
423 | </listitem>
|
---|
424 | </varlistentry>
|
---|
425 |
|
---|
426 | </variablelist>
|
---|
427 |
|
---|
428 | </sect2>
|
---|
429 |
|
---|
430 | </sect1>
|
---|