mirror of
https://gitlab.com/shorewall/code.git
synced 2024-11-30 11:33:28 +01:00
9dfa065abe
git-svn-id: https://shorewall.svn.sourceforge.net/svnroot/shorewall/trunk@8616 fbd18981-670d-0410-9b5c-8dc0c1a9a2bb
494 lines
19 KiB
XML
494 lines
19 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
|
|
<refentry>
|
|
<refmeta>
|
|
<refentrytitle>shorewall-masq</refentrytitle>
|
|
|
|
<manvolnum>5</manvolnum>
|
|
</refmeta>
|
|
|
|
<refnamediv>
|
|
<refname>masq</refname>
|
|
|
|
<refpurpose>Shorewall Masquerade/SNAT definition file</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<cmdsynopsis>
|
|
<command>/etc/shorewall/masq</command>
|
|
</cmdsynopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsect1>
|
|
<title>Description</title>
|
|
|
|
<para>Use this file to define dynamic NAT (Masquerading) and to define
|
|
Source NAT (SNAT).</para>
|
|
|
|
<warning>
|
|
<para>The entries in this file are order-sensitive. The first entry that
|
|
matches a particular connection will be the one that is used.</para>
|
|
</warning>
|
|
|
|
<warning>
|
|
<para>If you have more than one ISP, adding entries to this file will
|
|
*not* force connections to go out through a particular ISP. You must use
|
|
PREROUTING entries in <ulink
|
|
url="shorewall-tcrules.tcml">shorewall-tcrules</ulink>(5) to do
|
|
that.</para>
|
|
</warning>
|
|
|
|
<para>The columns in the file are as follows.</para>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><emphasis role="bold">INTERFACE</emphasis> - [<emphasis
|
|
role="bold">+</emphasis>]<emphasis>interfacelist</emphasis>[<emphasis
|
|
role="bold">:</emphasis>[<emphasis>digit</emphasis>]][<emphasis
|
|
role="bold">:</emphasis>[<emphasis>address</emphasis>[<emphasis
|
|
role="bold">,</emphasis><emphasis>address</emphasis>]...[<emphasis>exclusion</emphasis>]]</term>
|
|
|
|
<listitem>
|
|
<para>Outgoing <emphasis>interfacelist</emphasis>. Prior to
|
|
Shorewall 4.1.4, this must be a single interface name; in 4.1.4 and
|
|
later, this may be a comma-separated list of interface names. This
|
|
is usually your internet interface. If ADD_SNAT_ALIASES=Yes in
|
|
<ulink url="shorewall.conf.html">shorewall.conf</ulink>(5), you may
|
|
add ":" and a <emphasis>digit</emphasis> to indicate that you want
|
|
the alias added with that name (e.g., eth0:0). This will allow the
|
|
alias to be displayed with ifconfig. <emphasis role="bold">That is
|
|
the only use for the alias name; it may not appear in any other
|
|
place in your Shorewall configuratio</emphasis>n.</para>
|
|
|
|
<para>Each interface must match an entry in <ulink
|
|
url="shorewall-interfaces.html">shorewall-interfaces</ulink>(5).
|
|
Prior to Shorewall 4.1.4, this must be an exact match.
|
|
Shorewall-perl 4.1.4 and later allow loose matches to wildcard
|
|
entries in <ulink
|
|
url="shorewall-interfaces.html">shorewall-interfaces</ulink>(5). For
|
|
example, <filename class="devicefile">ppp0</filename> in this file
|
|
will match a <ulink
|
|
url="shorewall-interfaces.html">shorewall-interfaces</ulink>(5)
|
|
entry that defines <filename
|
|
class="devicefile">ppp+</filename>.</para>
|
|
|
|
<para>The interface may be qualified by adding the character ":"
|
|
followed by a comma-separated list of destination host or subnet
|
|
addresses to indicate that you only want to change the source IP
|
|
address for packets being sent to those particular destinations.
|
|
Exclusion is allowed (see <ulink
|
|
url="shorewall-exclusion.html">shorewall-exclusion</ulink>(5)).</para>
|
|
|
|
<para>If you wish to inhibit the action of ADD_SNAT_ALIASES for this
|
|
entry then include the ":" but omit the digit:</para>
|
|
|
|
<programlisting> eth0:
|
|
eth2::192.0.2.32/27</programlisting>
|
|
|
|
<para>Normally Masq/SNAT rules are evaluated after those for
|
|
one-to-one NAT (defined in <ulink
|
|
url="shorewall-nat.html">shorewall-nat</ulink>(5)). If you want the
|
|
rule to be applied before one-to-one NAT rules, prefix the interface
|
|
name with "+":</para>
|
|
|
|
<programlisting> +eth0
|
|
+eth0:192.0.2.32/27
|
|
+eth0:2</programlisting>
|
|
|
|
<para>This feature should only be required if you need to insert
|
|
rules in this file that preempt entries in <ulink
|
|
url="shorewall-nat.html">shorewall-nat</ulink>(5).</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><emphasis role="bold">SOURCE</emphasis> (Formerly called SUBNET)
|
|
-
|
|
{<emphasis>interface</emphasis>[[:]<emphasis>exclusion</emphasis>]|<emphasis>address</emphasis>[<emphasis
|
|
role="bold">,</emphasis><emphasis>address</emphasis>][<emphasis>exclusion</emphasis>]}</term>
|
|
|
|
<listitem>
|
|
<para>Set of hosts that you wish to masquerade. You can specify this
|
|
as an <emphasis>address</emphasis> (net or host) or as an
|
|
<emphasis>interface</emphasis>. If you give the name of an
|
|
interface, the interface must be up before you start the firewall
|
|
(Shorewall will use your main routing table to determine the
|
|
appropriate addresses to masquerade).</para>
|
|
|
|
<para>In order to exclude a address of the specified SOURCE, you may
|
|
append an <emphasis>exclusion</emphasis> ("!" and a comma-separated
|
|
list of IP addresses (host or net) that you wish to exclude (see
|
|
<ulink
|
|
url="shorewall-exclusion.html">shorewall-exclusion</ulink>(5))).
|
|
Note that with Shorewall-perl, a colon (":") must appear between an
|
|
<replaceable>interface</replaceable> name and the
|
|
<replaceable>exclusion</replaceable>;</para>
|
|
|
|
<para>Example (shorewall-shell):
|
|
eth1!192.168.1.4,192.168.32.0/27</para>
|
|
|
|
<para>Example (shorewall-perl):
|
|
eth1:!192.168.1.4,192.168.32.0/27</para>
|
|
|
|
<para>In that example traffic from eth1 would be masqueraded unless
|
|
it came from 192.168.1.4 or 196.168.32.0/27</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><emphasis role="bold">ADDRESS</emphasis> (Optional) - [<emphasis
|
|
role="bold">-</emphasis>|[<emphasis
|
|
role="bold">SAME:</emphasis>[<emphasis
|
|
role="bold">nodst:</emphasis>]][<emphasis>address-or-address-range</emphasis>[,<emphasis>address-or-address-range</emphasis>]...][:<emphasis>lowport</emphasis><emphasis
|
|
role="bold">-</emphasis><emphasis>highport</emphasis>][<emphasis
|
|
role="bold">:random</emphasis>]|<emphasis
|
|
role="bold">detect</emphasis>|<emphasis
|
|
role="bold">random</emphasis>]</term>
|
|
|
|
<listitem>
|
|
<para>If you specify an address here, SNAT will be used and this
|
|
will be the source address. If ADD_SNAT_ALIASES is set to Yes or yes
|
|
in <ulink url="shorewall.conf.html">shorewall.conf</ulink>(5) then
|
|
Shorewall will automatically add this address to the INTERFACE named
|
|
in the first column.</para>
|
|
|
|
<para>You may also specify a range of up to 256 IP addresses if you
|
|
want the SNAT address to be assigned from that range in a
|
|
round-robin fashion by connection. The range is specified by
|
|
<emphasis>first.ip.in.range</emphasis>-<emphasis>last.ip.in.range</emphasis>.
|
|
Beginning with Shorewall 4.0.6, you may follow the port range
|
|
with<emphasis role="bold"> :random</emphasis> in which case
|
|
assignment of ports from the list will be random. <emphasis
|
|
role="bold">random</emphasis> may also be specified by itself in
|
|
this column in which case random local port assignments are made for
|
|
the outgoing connections.</para>
|
|
|
|
<para>Example: 206.124.146.177-206.124.146.180</para>
|
|
|
|
<para>You may also use the special value "detect" which causes
|
|
Shorewall to determine the IP addresses configured on the interface
|
|
named in the INTERFACES column and substitute them in this
|
|
column.</para>
|
|
|
|
<para>Finally, you may also specify a comma-separated list of ranges
|
|
and/or addresses in this column.</para>
|
|
|
|
<para>This column may not contain DNS Names.</para>
|
|
|
|
<para>Normally, Netfilter will attempt to retain the source port
|
|
number. You may cause netfilter to remap the source port by
|
|
following an address or range (if any) by ":" and a port range with
|
|
the format
|
|
<emphasis>lowport</emphasis>-<emphasis>highport</emphasis>. If this
|
|
is done, you must specify "tcp" or "udp" in the PROTO column.</para>
|
|
|
|
<para>Examples:</para>
|
|
|
|
<programlisting> 192.0.2.4:5000-6000
|
|
:4000-5000</programlisting>
|
|
|
|
<para>You can invoke the SAME target rather than the SNAT target by
|
|
prefixing the column contents with <option>SAME:</option>.</para>
|
|
|
|
<para>SAME works like SNAT with the exception that the same local IP
|
|
address is assigned to each connection from a local address to a
|
|
given remote address.</para>
|
|
|
|
<para>If the <option>nodst:</option> option is included, then the
|
|
same source address is used for a given internal system regardless
|
|
of which remote system is involved.<warning>
|
|
<para>Support for the SAME target is scheduled for removal from
|
|
the Linux kernel in 2008.</para>
|
|
</warning></para>
|
|
|
|
<para>If you want to leave this column empty but you need to specify
|
|
the next column then place a hyphen ("-") here.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><emphasis role="bold">PROTO</emphasis> (Optional) - {<emphasis
|
|
role="bold">-</emphasis>|<emphasis>protocol-name</emphasis>|<emphasis>protocol-number</emphasis>}</term>
|
|
|
|
<listitem>
|
|
<para>If you wish to restrict this entry to a particular protocol
|
|
then enter the protocol name (from protocols(5)) or number
|
|
here.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><emphasis role="bold">PORT(S)</emphasis> (Optional) -
|
|
[<emphasis>port-name-or-number</emphasis>[,<emphasis>port-name-or-number</emphasis>]...]</term>
|
|
|
|
<listitem>
|
|
<para>If the PROTO column specifies TCP (protocol 6) or UDP
|
|
(protocol 17) then you may list one or more port numbers (or names
|
|
from services(5)) separated by commas or you may list a single port
|
|
range
|
|
(<emphasis>lowport</emphasis>:<emphasis>highport</emphasis>).</para>
|
|
|
|
<para>Where a comma-separated list is given, your kernel and
|
|
iptables must have multiport match support and a maximum of 15 ports
|
|
may be listed.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><emphasis role="bold">IPSEC</emphasis> (Optional) -
|
|
[<emphasis>option</emphasis>[<emphasis
|
|
role="bold">,</emphasis><emphasis>option</emphasis>]...]</term>
|
|
|
|
<listitem>
|
|
<para>If you specify a value other than "-" in this column, you must
|
|
be running kernel 2.6 and your kernel and iptables must include
|
|
policy match support.</para>
|
|
|
|
<para>Comma-separated list of options from the following. Only
|
|
packets that will be encrypted via an SA that matches these options
|
|
will have their source address changed.</para>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><emphasis
|
|
role="bold">reqid=</emphasis><emphasis>number</emphasis></term>
|
|
|
|
<listitem>
|
|
<para>where <emphasis>number</emphasis> is specified using
|
|
setkey(8) using the 'unique:<emphasis>number</emphasis> option
|
|
for the SPD level.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><emphasis role="bold">spi=</emphasis><number></term>
|
|
|
|
<listitem>
|
|
<para>where <emphasis>number</emphasis> is the SPI of the SA
|
|
used to encrypt/decrypt packets.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><emphasis role="bold">proto=</emphasis><emphasis
|
|
role="bold">ah</emphasis>|<emphasis
|
|
role="bold">esp</emphasis>|<emphasis
|
|
role="bold">ipcomp</emphasis></term>
|
|
|
|
<listitem>
|
|
<para>IPSEC Encapsulation Protocol</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><emphasis
|
|
role="bold">mss=</emphasis><emphasis>number</emphasis></term>
|
|
|
|
<listitem>
|
|
<para>sets the MSS field in TCP packets</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><emphasis role="bold">mode=</emphasis><emphasis
|
|
role="bold">transport</emphasis>|<emphasis
|
|
role="bold">tunnel</emphasis></term>
|
|
|
|
<listitem>
|
|
<para>IPSEC mode</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><emphasis
|
|
role="bold">tunnel-src=</emphasis><emphasis>address</emphasis>[/<emphasis>mask</emphasis>]</term>
|
|
|
|
<listitem>
|
|
<para>only available with mode=tunnel</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><emphasis
|
|
role="bold">tunnel-dst=</emphasis><emphasis>address</emphasis>[/<emphasis>mask</emphasis>]</term>
|
|
|
|
<listitem>
|
|
<para>only available with mode=tunnel</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><emphasis role="bold">strict</emphasis></term>
|
|
|
|
<listitem>
|
|
<para>Means that packets must match all rules.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><emphasis role="bold">next</emphasis></term>
|
|
|
|
<listitem>
|
|
<para>Separates rules; can only be used with strict</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><emphasis role="bold">MARK</emphasis> - [<emphasis
|
|
role="bold">!</emphasis>]<emphasis>value</emphasis>[/<emphasis>mask</emphasis>][<emphasis
|
|
role="bold">:C</emphasis>]</term>
|
|
|
|
<listitem>
|
|
<para>Defines a test on the existing packet or connection mark. The
|
|
rule will match only if the test returns true.</para>
|
|
|
|
<para>If you don't want to define a test but need to specify
|
|
anything in the following columns, place a "-" in this field.</para>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>!</term>
|
|
|
|
<listitem>
|
|
<para>Inverts the test (not equal)</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><emphasis>value</emphasis></term>
|
|
|
|
<listitem>
|
|
<para>Value of the packet or connection mark.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><emphasis>mask</emphasis></term>
|
|
|
|
<listitem>
|
|
<para>A mask to be applied to the mark before testing.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><emphasis role="bold">:C</emphasis></term>
|
|
|
|
<listitem>
|
|
<para>Designates a connection mark. If omitted, the packet
|
|
mark's value is tested. This option is only supported by
|
|
Shorewall-perl.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Examples</title>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>Example 1:</term>
|
|
|
|
<listitem>
|
|
<para>You have a simple masquerading setup where eth0 connects to a
|
|
DSL or cable modem and eth1 connects to your local network with
|
|
subnet 192.168.0.0/24.</para>
|
|
|
|
<para>Your entry in the file can be either:</para>
|
|
|
|
<programlisting> #INTERFACE SOURCE
|
|
eth0 eth1</programlisting>
|
|
|
|
<para>or</para>
|
|
|
|
<programlisting> #INTERFACE SOURCE
|
|
eth0 192.168.0.0/24</programlisting>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term>Example 2:</term>
|
|
|
|
<listitem>
|
|
<para>You add a router to your local network to connect subnet
|
|
192.168.1.0/24 which you also want to masquerade. You then add a
|
|
second entry for eth0 to this file:</para>
|
|
|
|
<programlisting> #INTERFACE SOURCE
|
|
eth0 192.168.1.0/24</programlisting>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term>Example 3:</term>
|
|
|
|
<listitem>
|
|
<para>You have an IPSEC tunnel through ipsec0 and you want to
|
|
masquerade packets coming from 192.168.1.0/24 but only if these
|
|
packets are destined for hosts in 10.1.1.0/24:</para>
|
|
|
|
<programlisting> #INTERFACE SOURCE
|
|
ipsec0:10.1.1.0/24 196.168.1.0/24</programlisting>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term>Example 4:</term>
|
|
|
|
<listitem>
|
|
<para>You want all outgoing traffic from 192.168.1.0/24 through eth0
|
|
to use source address 206.124.146.176 which is NOT the primary
|
|
address of eth0. You want 206.124.146.176 to be added to eth0 with
|
|
name eth0:0.</para>
|
|
|
|
<programlisting> #INTERFACE SOURCE ADDRESS
|
|
eth0:0 192.168.1.0/24 206.124.146.176</programlisting>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term>Example 5:</term>
|
|
|
|
<listitem>
|
|
<para>You want all outgoing SMTP traffic entering the firewall on
|
|
eth1 to be sent from eth0 with source IP address 206.124.146.177.
|
|
You want all other outgoing traffic from eth1 to be sent from eth0
|
|
with source IP address 206.124.146.176.</para>
|
|
|
|
<programlisting> #INTERFACE SOURCE ADDRESS PROTO PORT(S)
|
|
eth0 eth1 206.124.146.177 tcp smtp
|
|
eth0 eth1 206.124.146.176</programlisting>
|
|
|
|
<warning>
|
|
<para>The order of the above two rules is significant!</para>
|
|
</warning>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>FILES</title>
|
|
|
|
<para>/etc/shorewall/masq</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>See ALSO</title>
|
|
|
|
<para>shorewall(8), shorewall-accounting(5), shorewall-actions(5),
|
|
shorewall-blacklist(5), shorewall-exclusion(5), shorewall-hosts(5),
|
|
shorewall-interfaces(5), shorewall-ipsec(5), shorewall-maclist(5),
|
|
shorewall-nat(5), shorewall-netmap(5), shorewall-params(5),
|
|
shorewall-policy(5), shorewall-providers(5), shorewall-proxyarp(5),
|
|
shorewall-route_rules(5), shorewall-routestopped(5), shorewall-rules(5),
|
|
shorewall.conf(5), shorewall-tcclasses(5), shorewall-tcdevices(5),
|
|
shorewall-tcrules(5), shorewall-tos(5), shorewall-tunnels(5),
|
|
shorewall-zones(5)</para>
|
|
</refsect1>
|
|
</refentry> |