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shorewall_code/Shorewall/releasenotes.txt
Tom Eastep 798dde23c8 Modest update to Packet processing doc
2009-04-30 19:11:16 -07:00

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Shorewall 4.3.10
Shorewall 4.3 is the development thread for Shorewall 4.4 which will be
released late in 2009.
----------------------------------------------------------------------------
R E L E A S E 4 . 3 H I G H L I G H T S
----------------------------------------------------------------------------
1) Support for Shorewall-shell has been discontinued. Shorewall-perl
has been combined with Shorewall-common to produce a single
Shorewall package.
2) The Shorewall documentation and man pages have been purged of
information about earlier Shorewall releases. The documentation
describes only the behavior of Shorewall 4.3 and later versions.
3) The interfaces file OPTIONs have been extended to largely remove the
need for the hosts file.
4) It is now possible to define PREROUTING and OUTPUT marking rules
that cause new connections to use the same provider as an existing
connection of the same kind.
5) Dynamic Zone support is once again available for IPv4; ipset support is
required in your kernel and in iptables.
6) A new AUTOMAKE option has been added to shorewall.conf and
shorewall6.conf. Setting this option will allow Shorewall to skip
the compilation phase during start/restart if no configuration
changes have occurred since the last start/restart.
7) The LIMIT:BURST column in /etc/shorewall/policy
(/etc/shorewall6/policy) and the RATE LIMIT column in
/etc/shorewall/rules (/etc/shorewall6/rules) may now be used to
limit on a per source IP or per destination IP basis.
8) Support for per-IP traffic shaping classes has been added.
----------------------------------------------------------------------------
M I G R A T I O N I S S U E S
----------------------------------------------------------------------------
1) The 'shorewall stop', 'shorewall clear', 'shorewall6 stop' and
'shorewall6 clear' commands no longer read the 'routestopped'
file. The 'routestopped' file used is the one that was present at
the last 'start', 'restart' or 'restore' command.
2) The old macro parameter syntax (e.g., SSH/ACCEPT) is now deprecated
in favor of the new syntax (e.g., SSH(ACCEPT)). The 4.3 documentation
uses the new syntax exclusively, although the old syntax
continues to be supported.
3) Support for the SAME target in /etc/shorewall/masq and
/etc/shorewall/rules has been removed, following the removal of the
underlying support in the Linux kernel.
4) Supplying an interface name in the SOURCE column of
/etc/shorewall/masq is now deprecated. Entering the name of an
interface there will result in a compile-time warning:
WARNING: Using an interface as the masq SOURCE requires the
interface to be up and configured when Shorewall
starts/restarts
To avoid this warning, replace interface names by the corresponding
network addresses (e.g., 192.168.144.0/24).
----------------------------------------------------------------------------
P R O B L E M S C O R R E C T E D I N 4 . 3 . 10
----------------------------------------------------------------------------
1. When Shorewall could not determine the MAC address of of a gateway
router where multiple providers are configured through the same
interface, invalid iptables-restore input was generated. This
resulted in an error message similar to the following:
iptables-restore v1.3.5: Bad mac address `-j'
2. Previously, Shorewall has treated traffic shaping class IDs as
decimal numbers (or pairs of decimal numbers). That worked fine
until IPMARK was implemented. IPMARK requires Shorewall to generate
class Ids in numeric sequence. In 4.3.9, that didn't work correctly
because Shorewall was generating the sequence "..8,9,10,11..." when
the correct sequence was "...8,9,a,b,...". Shorewall now treats
class IDs as hex, like 'tc' and 'iptables' do.
----------------------------------------------------------------------------
K N O W N P R O B L E M S R E M A I N I N G
----------------------------------------------------------------------------
None.
----------------------------------------------------------------------------
N E W F E A T U R E S I N 4 . 3 . 10
----------------------------------------------------------------------------
1) The change that implemented IPMARK support in 4.3.9 resulted in a
lack of upward compatibility which could break some
configurations. The incompatibility stems from the way in which
Shorewall generates a TC class Id from a mark value.
- Prior to 4.3.9, the class number was constructed by concatinating
the either '1' or '10' with the mark value. '10' is used when
there are more than 10 devices defined in /etc/shorewall/tcdevices.
- In 4.3.9, the class number is constructed by shifting
the device number left by 10 bits and logically ORing the result
with the mark value.
- In 4.3.10, a new method is added; the mark value is logically
ORed with 0x40000000;
The WIDE_TC_MARKS option in shorewall.conf selects which
construction to use. WIDE_TC_MARKS=No (the default) produces
pre-4.3.9 behavior. WIDE_TC_MARKS=Yes produces the new behavior.
In addition to determining the method of constructing class Ids,
WIDE_TC_MARKS=Yes provides for larger mark values for traffic
shaping. Traffic shaping marks may have values up to 16383 (0x3fff)
with WIDE_TC_MARKS=Yes. This means that when both WIDE_TC_MARKS=Yes and
HIGH_ROUTE_MARKS=Yes, routing marks (/etc/shorewall/providers MARK
column) must be >= 65536 (0x10000) and must be a multiple of 65536
(0x1000, 0x20000, 0x30000, ...).
2) In the 'shorewall compile' command, the filename '-' is now causes
the compiled script to be written to Standard Out. As a side
effect, the effective VERBOSITY is set to -1 (silent).
Examples:
shorewall compile -- - # Compile the configuration in
# /etc/shorewall and send the
# output to STDOUT
shorewall compile . - # Compile the configuration in the
# current working directory
# and send the output to STDOUT
3) Supplying an interface name in the SOURCE column of
/etc/shorewall/masq is now deprecated. Entering the name of an
interface there will result in a compile-time warning.
----------------------------------------------------------------------------
N E W F E A T U R E S IN 4 . 3
----------------------------------------------------------------------------
1) The Shorewall packaging has been completely revamped in Shorewall
4.3.
The new packages are:
- Shorewall. Includes the former Shorewall-common and
Shorewall-perl packages. Includes everything needed
to create an IPv4 firewall.
- Shorewall6. Requires Shorewall. Adds the components necessary to
create an IPv6 firewall.
- Shorewall-lite
May be installed on a firewall system to run
IPv4 firewall scripts generated by Shorewall.
- Shorewall6-lite
May be installed on a firewall system to run
IPv6 firewall scripts generated by Shorewall6.
2) The interfaces file supports a new 'nets=' option. This option
allows users to restrict a zone's definition to particular networks
through an interface without having to use the hosts file.
Example interfaces file:
#ZONE INTERFACE BROADCAST OPTIONS
loc eth3 detect dhcp,logmartians=1,routefilter=1,nets=172.20.1.0/24
dmz eth4 detect logmartians=1,routefilter=1,nets=206.124.146.177
net eth0 detect dhcp,blacklist,tcpflags,optional,routefilter=0,nets=(!172.20.0.0/24,206.124.146.177)
net eth2 detect dhcp,blacklist,tcpflags,optional,upnp,routefilter=0,nets=(!172.20.0.0/24,206.124.146.177)
loc tun+ detect nets=172.20.0.0/24
#LAST LINE -- ADD YOUR ENTRIES BEFORE THIS ONE -- DO NOT REMOVE
Note that when more than one network address is listed, the list
must be enclosed in parentheses. Notice also that exclusion may be
used.
The first entry in the above interfaces file is equivalent to the
following:
interfaces:
#ZONE INTERFACE BROADCAST OPTIONS
- eth0 detect dhcp,logmartians=1,routefilter=1
hosts:
#ZONE HOST(S) OPTIONS
loc $INT_IF:192.20.1.0/24 broadcast
Note that the 'broadcast' option is automatically assumed and need
not be explicitly specified.
3) Some websites run applications that require multiple connections
from a client browser. Where multiple 'balanced' providers are
configured, this can lead to problems when some of the connections
are routed through one provider and some through another.
To work around this issue, the SAME target has been added to
/etc/shorewall/tcrules. SAME may be used in the PREROUTING and
OUTPUT chains. When used in PREROUTING, it causes matching
connections from an individual local system to all use the same
provider.
For example:
SAME:P 192.168.1.0/24 - tcp 80,443
If a host in 192.168.1.0/24 attempts a connection on TCP port 80 or
443 and it has sent a packet on either of those ports in the last
five minutes then the new connection will use the same provider as
the connection over which that last packet was sent.
When used in the OUTPUT chain, it causes all matching connections
to an individual remote system to all use the same provider.
For example:
SAME $FW - tcp 80,443
If the firewall attempts a connection on TCP port 80 or
443 and it has sent a packet on either of those ports in the last
five minutes to the same remote system then the new connection will
use the same provider as the connection over which that last packet
was sent.
Important note: SAME only works with providers that have the
'track' option specified in /etc/shorewall/providers.
4) The file /var/lib/shorewall/.restore has been renamed to
/var/lib/shorewall/firewall. A similar change has been made in
Shorewall6.
When a successful start or restart is completed, the script that
executed the command copies itself to to
/var/lib/shorewall[6]/firewall.
5) Dynamic zone support is once again available for IPv4. This support
is built on top of ipsets so you must have the xtables-addons
installed on the firewall system.
Dynamic zones are available when Shorewall-lite is used as well.
Note that the dynamic zone support built into Shorewall provides no
additional functionality over what is provided by simply defining a
zone in terms of an ipset (see
http://www1.shorewall.net/ipsets.html#Dynamic).
You define a zone as having dynamic content in one of two ways:
- By specifying nets=dynamic in the OPTIONS column of an entry for
the zone in /etc/shorewall/interfaces; or
- By specifying <interface>:dynamic in the HOST(S) column of an
entry for the zone in /etc/shorewall/hosts.
When there are any dynamic zones present in your configuration,
Shorewall (Shorewall-lite) will:
a) Execute the following commands during 'shorewall start' or
'shorewall-lite start'.
ipset -U :all: :all:
ipset -U :all: :default:
ipset -F
ipset -X
ipset -R < ${VARDIR}/ipsets.save
where $VARDIR normally contains /var/lib/shorewall
(/var/lib/shorewall-lite) but may be modified by
/etc/shorewall/vardir (/etc/shorewall-lite/vardir).
b) During 'start', 'restart' and 'restore' processing, Shorewall
will then attempt to create an ipset named <zone>_<interface>
for each zone/interface pair that has been specified as
dynamic. The type of ipset created is 'iphash' so that only
individual IPv4 addresses may be added to the set.
c) Execute the following commands during 'shorewall stop' or
'shorewall-lite stop':
if ipset -S > ${VARDIR}/ipsets.tmp; then
mv -f ${VARDIR}/ipsets.tmp ${VARDIR}/ipsets.save
fi
The 'shorewall add' and 'shorewall delete' commands are supported
with their original syntax:
add <interface>[:<host-list>] ... <zone>
delete <interface>[:<host-list>] ... <zone>
In addition, the 'show dynamic' command is added that lists the dynamic
content of a zone.
show dynamic <zone>
These commands are supported by shorewall-lite as well.
6) The generated program now attempts to detect all dynamic
information when it first starts. If any of those steps fail, an
error message is generated and the state of the firewall is not
changed.
7) Shorewall will now attempt to detect a dynamic gateway by reading
the dhclient lease file for the interface
(/var/run/dhcp/dhclient-<if>.lease).
8) To improve readability of the configuration files, Shorewall now
allows leading white space in continuation lines when the continued
line ends in ":" or ",".
Example (/etc/shorewall/rules):
#ACTION SOURCE DEST PROTO DEST
# PORT(S)
ACCEPT net:\
206.124.146.177,\
206.124.146.178,\
206.124.146.180\
dmz tcp 873
The leading white space on the lines that contain just an IP
address is ignored so the SOURCE column effectively contains
"net:206.124.146.177,206.124.147.178,206.124.146.180".
9) The generated script now uses iptables[6]-restore to instantiate
the Netfilter ruleset during processing of the 'stop' command. As a
consequence, the 'critical' option in /etc/shorewall/route_stopped
is no longer needed and will result in a warning.
10) A new AUTOMAKE option has been added to shorewall.conf and
shorewall6.conf. When set to 'Yes', this option causes new behavior
during processing of the 'start' and 'restart' commands; if no
files in /etc/shorewall/ (/etc/shorewall6) have changed since the last
'start' or 'restart', then the compilation step is skipped and the
script used during the last 'start' or 'restart' is used to
start/restart the firewall.
Note that if a <directory> is specified in the start/restart
command (e.g., "shorewall restart /etc/shorewall.new") then the
setting of AUTOMAKE is ignored.
Note that the 'make' utility must be installed on the firewall
system in order for AUTOMAKE=Yes to work correctly.
11) The 'compile' command now allows you to omit the <pathname>. When
you do that, the <pathname> defaults to /var/lib/shorewall/firewall
(/var/lib/shorewall6/firewall) unless you have overridden VARDIR
using /etc/shorewall/vardir (/etc/shorewall6/vardir).
When combined with AUTOMAKE=Yes, it allows the following:
gateway:~ # shorewall compile
Compiling...
Shorewall configuration compiled to /root/shorewall/firewall
gateway:~ #
...
gateway:~ # shorewall restart
Restarting Shorewall....
done.
gateway:~ #
In other words, you can compile the current configuration then
install it at a later time.
12) Thanks to I. Buijs, it is now possible to rate-limit connections by
source IP or destination IP. The LIMIT:BURST column in
/etc/shorewall/policy (/etc/shorewall6/policy) and the RATE LIMIT
column /etc/shorewall/rules (/etc/shorewall6/rules) have been
extended as follows:
[{s|d}:[[<name>]:]]<rate>/{sec|min}[:<burst>]
When s: is specified, the rate is per source IP address.
When d: is specified, the rate is per destination IP address.
The <name> specifies the name of a hash table -- you get to choose
the name. If you don't specify a name, the name 'shorewall' is
assumed. Rules with the same name have their connection counts
aggregated and the individual rates are applied to the aggregate.
Example:
ACCEPT net fw tcp 22 - - s:ssh:3/min
This will limit SSH connections from net->fw to 3 per minute.
ACCEPT net fw tcp 25 - - s:mail:3/min
ACCEPT net fw tcp 587 - - s:mail:3/min
Since the same hash table name is used in both rules, the above is
equivalent to this single rule:
ACCEPT net fw tcp 25,587 - - s:mail:3/min
13) Rules that specify a log level with a target other than LOG or NFLOG
are now implemented through a separate chain. While this may increase
the processing cost slightly for packets that match these rules, it
is expected to reduce the overall cost of such rules because each
packet that doesn't match the rules only has to be processed once
per rule rather than twice.
Example:
/etc/shorewall/rules:
REJECT:info loc net tcp 25
This previously generated these two rules (long rules folded):
-A loc2net -p 6 --dport 25 -j LOG --log-level 6
--log-prefix "Shorewall:loc2net:reject:"
-A loc2net -p 6 --dport 25 -j reject
It now generates these rules:
:log0 - [0:0]
...
-A loc2net -p 6 --dport 25 -g log0
...
-A log0 -j LOG --log-level 6
--log-prefix "Shorewall:loc2net:REJECT:"
-A log0 -p 6 --dport 25 -j reject
Notice that now there is only a single rule generated in the
'loc2net' chain where before there were two. Packets for other than
TCP port 25 had to be processed by both rules.
Notice also that the new LOG rule reflects the original action
("REJECT") rather than what Shorewall maps that to ("reject").
14) Shorewall6 has now been tested on kernel 2.6.24 (Ubuntu Hardy) and
hence will now start successfully when running on that kernel.
15) Three new options (IP, TC and IPSET) have been added to
shorewall.conf and shorwall6.conf. These options specify the name
of the executable for the 'ip', 'tc' and 'ipset' utilities
respectively.
If not specified, the default values are:
IP=ip
TC=tc
IPSET=ipset
In other words, the utilities will be located via the current PATH
setting.
16) There has been a desire in the user community to limit traffic by
IP address using Shorewall traffic shaping. Heretofore, that has
required a very inefficient process:
a) Define a tcclass for each internal host (two, if shaping both in
and out).
b) Define a tcrule for each host to mark to classify the packets
accordingly.
Beginning with Shorewall 4.3.9, this process is made easier IF YOU
ARE WILLING TO INSTALL xtables-addons. The feature requires IPMARK
support in iptables[6] and your kernel. That support is available
in xtables-addons.
The new facility has two components:
a) A new IPMARK MARKing command in /etc/shorewall/tcrules.
b) A new 'occurs' OPTION in /etc/shorewall/tcclasses.
The IPMARK target assigns a mark to each matching packet based on
the either the source or destination IP address. By default, it
assigns a mark value equal to the low-order 8 bits of the source
address.
The syntax is as follows:
IPMARK[([{src|dst}][,[<mask1>][,[<mask2>][,[<shift>]]]])]
Default values are:
src
<mask1> = 0xFF
<mask2> = 0x00
<shift> = 0
'src' and 'dst' specify whether the mark is to be based on the
source or destination address respectively.
The selected address is first LANDed with <mask1> then LORed with
<mask2>.
The result is then shifted <shift> bits to the right.
Example:
IPMARK(dst, 0XFF00, 0x8000,8)
Destination IP address is 192.168.4.3 = 0xc0a80403
0xc0a80403 LAND 0xFF00 = 0x0400
0x0400 LOR 0x80 = 0x8400
0x8400 >> 8 = 0x84
Mark = 0x84 = 132
The 'occurs' option causes the class definition to be replicated
many times. The synax is:
occurs=<number>
When 'occurs' is used:
a) The associated device may not have the 'classify' option.
b) The class may not be the default class.
c) The class may not have any 'tos=' options (including
'tcp-ack').
The 'RATE' and 'CEIL' parameters apply to each instance of the
class. So the total RATE represented by an entry with 'occurs' will
be the listed RATE multiplied by the 'occurs' number.
Example:
#DEVICE MARK RATE CEIL PRIORITY OPTIONS
eth0 100 1kbit 230kbit 4 occurs=32
The above defines 32 classes with MARK values 100-131. Each
class has a guaranteed rate of 1kbit/second.
As part of this change, the generation of class ids from mark
values has been changed. The class number is now
( <devnum> << 10 ) | <mask>
/sbin/shorewall has an 'encode' and 'decode' command to translate a
device number, mark pair to/from a classid:
encode <devnum> <mark>
decode <classnum>
Example:
$ shorewall decode 3172
Device = 3 Mark = 100
$ shorewall encode 3 100
Class number = 3172
$
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