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shorewall_code/Shorewall/releasenotes.txt

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Shorewall 3.4.0 Beta 1
Release Highlights
1) Shorewall can now be taylored to reduce its footprint on embedded
systems. As part of this change, actions are now completely optional.
2) Exclusion is now possible in /etc/shorewall/hosts. This is required
for bridge/firewalls under kernel 2.6.20 and later.
3) Shorewall and Shorewall Lite now include man pages. There is a
man page for shorewall(8), one for shorewall-lite(8) and one for
each configuration file. As part of this change, all documentation
has been removed from Shorewall configuration files. This should
make it easier from users to upgrade from one release to the next
since the configuration files will only change when column is added
or renamed.
Migration Considerations:
1) Shorewall supports the notion of "default actions". A default
action defines a set of rules that are applied before a policy is
enforced. Default actions accomplish two goals:
a) Relieve log congestion. Default actions typically include rules
to silently drop or reject traffic that would otherwise be logged
when the policy is enforced.
b) Insure correct operation. Default actions can also avoid common
pitfalls like dropping connection requests on TCP port 113. If
these connections are dropped (rather than rejected) then you
may encounter problems connecting to internet services that
utilize the AUTH protocol of client authentication.
In prior Shorewall versions, default actions (action.Drop and
action.Reject) were defined for DROP and REJECT policies in
/usr/share/shorewall/actions.std. These could be overridden in
/etc/shorewall/actions.
This approach has two drawbacks:
a) All DROP policies must use the same default action and all
REJECT policies must use the same default action.
b) Now that we have modularized action processing (see the New
Features section below), we need a way to define default rules
for a policy that does not involve actions.
If you have not overridden the defaults using entries in
/etc/shorewall/actions then you need make no changes to migrate to
Shorewall version 3.3. Otherwise, please see item 3) in the New
Features below.
2) The 'Limit' action is now a builtin. If you have 'Limit' listed in
/etc/shorewall/actions, remove the entry. Also remove the files
/etc/shorewall/action.Limit and/or /etc/shorewall/Limit if you have
them.
New Features in Shorewall 3.4:
1) In order to accomodate small embedded applications, Shorewall 3.4
is now modularized. In addition to the base files, there are
loadable "libraries" that may be included or omitted from an
embedded system as required.
Loadable Shorewall libraries reside in /usr/share/shorewall/ and
have names that begin with "lib.". The following libraries are
included in Shorewall 3.4:
- lib.accounting. Must be available if you include entries in
/etc/shorewall/accounting.
- lib.actions. Must be available if you do not specify
USE_ACTIONS=No in /etc/shorewall/shorewall.conf.
- lib.base. The base Shorewall library required by all programs,
including compiled firewall scripts.
- lib.cli. Library containing the code common to /sbin/shorewall,
/sbin/shorewall-lite.
- lib.config. Library containing the code that is common to
/usr/share/shorewall/compiler and /usr/share/shorewall/firewall.
- lib.dynamiczones. Must be available if you specify
DYNAMIC_ZONES=Yes in shorewall.conf.
- lib.maclist. Must be available if you specify the 'maclist'
option in /etc/shorewall/interfaces or /etc/shorewall/hosts.
- lib.nat. Must be available if you have entries in
/etc/shorewall/masq, /etc/shorewall/nat or /etc/shorewall/netmap
or if you use DNAT or REDIRECT rules.
- lib.providers. Must be available if you have entries in
/etc/shorewall/providers.
- lib.proxyarp. Must be available if you have entries in
/etc/shorewall/proxyarp or if you specify the 'proxyarp' option
in /etc/shorewall/interfaces.
- lib.tc. Must be available if you have entries in
/etc/shorewall/tcdevices and /etc/shorewall/tcclasses.
- lib.tcrules. Must be available if you have entries in
/etc/shorewall/tcrules.
- lib.tunnels. Must be available if you have entries in
/etc/shorewall/tunnels.
Embedded applications can further decrease the size of the Shorewall
footprint by:
- Omitting the macro files.
- Omitting all unused extension scripts.
2) As hinted in the previous bullet, there is a new USE_ACTIONS option
in /etc/shorewall/shorewall.conf. Shorewall actions can be very
powerful but they also require a lot of code to implement. Embedded
applications can omit that code by setting
USE_ACTIONS=No. Shorewall will ignore all action-related files
including /usr/share/shorewall/actions.std and
/etc/shorewall/actions. Builtin actions will still be available for
use in rules and macros.
The 'Limit' action has been converted to a builtin so that Limit is
available even when USE_ACTIONS=No.
See the next item for more information.
3) Prior to Shorewall 3.3, default actions were specified in
/usr/share/shorewall/actions.std or in /etc/shorewall/actions.
This approach has two drawbacks:
a) All DROP policies must use the same default action and all
REJECT policies must use the same default action.
b) Now that we have modularized action processing (see the New
Features section below), we need a way to define default rules
for a policy that does not involve actions.
The solution is two-fold:
- Four new options have been added to the
/etc/shorewall/shorewall.conf file that allow specifying the
default action for DROP, REJECT, ACCEPT and QUEUE.
The options are DROP_DEFAULT, REJECT_DEFAULT, ACCEPT_DEFAULT and
QUEUE_DEFAULT.
DROP_DEFAULT describes the rules to be applied before a
connection request is dropped by a DROP policy; REJECT_DEFAULT
describes the rules to be applied if a connection request is
rejected by a REJECT policy. The other two are similar for
ACCEPT and QUEUE policies.
The value assigned to these may be:
a) The name of an action.
b) The name of a macro
c) 'None' or 'none'
The default values are:
DROP_DEFAULT="Drop"
REJECT_DEFAULT="Reject"
ACCEPT_DEFAULT=none
QUEUE_DEFAULT=none
If USE_ACTIONS=Yes, then these values refer to action.Drop and
action.Reject respectively. If USE_ACTIONS=No, then these values
refer to macro.Drop and macro.Reject.
If you set the value of either option to "None" then no default
action will be used and the default action or macro (if any)
must be specified in /etc/shorewall/policy
- The POLICY column in /etc/shorewall/policy has been extended.
In /etc/shorewall/policy, when the POLICY is DROP, REJECT,
ACCEPT or QUEUE then the policy may be followed by ":" and one
of the following:
a) The word "None" or "none". This causes any default
action defined in /etc/shorewall/shorewall.conf
to be omitted for this policy.
b) The name of an action (requires that USE_ACTIONS=Yes
in shorewall.conf). That action will be invoked
before the policy is enforced.
c) The name of a macro. The rules in that macro will
be applied before the policy is enforced. This
does not require USE_ACTIONS=Yes.
Example:
#SOURCE DEST POLICY LOG
# LEVEL
loc net ACCEPT
net all DROP:MyDrop info
#
# THE FOLLOWING POLICY MUST BE LAST
#
all all REJECT:MyReject info
4) For users whose kernel and iptables have Extended MARK Target
support, it is now possible to logically AND or OR a value into the
current packet mark by preceding the mark value (and optional mask)
with an ampersand ("&") or vertical bar ("|") respectively.
Example: To logically OR the value 4 into the mark value for
packets from 192.168.1.1:
#MARK SOURCE
|4 192.168.1.1
5) Previously, zone names were restricted to five characters in
length. That limit derives from the --log-prefix in Netfilter log
messages which must be 29 bytes or less in length. With the
standard Shorewall LOGFORMAT, that leaves 11 characters for the
chain name; given that many chain names are of the form
<zone1>2<zone2>, that gives a maximum zone name length of 5.
Beginning with this release, the maximum length of a zone name is
dependent on the LOGFORMAT (the maximum length may never be less
than 5 but it may be greater than 5). For example, setting
LOGFORMAT="FW:%s:%s:" will allow zone names of up to 8 characters.
6) Netfilter provides support for attachmend of comments to Netfilter
rules. Comments can be up to 255 bytes in length and are visible
using the "shorewall show <chain>", "shorewall show nat",
"shorewall show mangle" and "shorewall dump" commands. Comments are
delimited by '/* ... */" in the output.
Beginning with Shorewall 3.3.3, you may place COMMENT lines in the
/etc/shorewall/rules, /etc/shorewall/tcrules, /etc/shorewall/nat
and /etc/shorewall/masq files and in action files. The remainder of
the line is treated as a comment and it will be attached as a
Netfilter comment to the rule(s) generated by succeding entries
in the file.
Note: Do not prefix the comment with "#". Shorewall's two-pass
compiler strips off "#" comments in the first pass and processes
COMMENT lines in the second pass. Hence, by the time that COMMENT
is processed, the "#" and everything following it has been removed
(see example below).
To stop the current comment from being attached to further
rules, simply include COMMENT on a line by itself (so that the
following rules will have no comment) or specify a new COMMENT.
If you do not have Comment support in your iptables/kernel (see the
output of "shorewall[-lite] show capabilities") then COMMENTS are
ignored with this warning:
COMMENT ignored -- requires comment support in iptables/Netfilter
Example from my rules file:
#SOURCE SOURCE DEST PROTO DEST PORT(S)
COMMENT Stop Microsoft Noise
REJECT loc net tcp 137,445
REJECT loc net udp 137:139
COMMENT # Stop comment from being attached to rules below
The output of "shorewall show loc2net" includes (folded):
0 0 reject tcp -- * * 0.0.0.0/0
0.0.0.0/0 multiport dports 137,445 /* Stop Microsoft Noise */
0 0 reject udp -- * * 0.0.0.0/0
0.0.0.0/0 udp dpts:137:139 /* Stop Microsoft Noise */
7) A new macro (macro.RDP) has been added for Microsoft Remote
Desktop. This macro was contributed by Tuomo Soini.
8) A new 'maclog' extension file has been added. This file is
processed just before logging based on the setting of
MACLIST_LOG_LEVEL is done. When the extension is invoked, the CHAIN
variable will contain the name of the chain where rules should be
inserted. Remember that if you have specified MACLIST_TABLE=mangle,
then your run_iptables commands should include "-t mangle".
9) The SUBNET column in /etc/shorewall/masq has been renamed SOURCE to
more accurately describe the contents of the column.
10) Previously, it was not possible to use exclusion in
/etc/shorewall/hosts. Beginning with this release, you may now use
exclusion lists in entries in this file. Exclusion lists are
discussed at:
http://www.shorewall.net/configuration_file_basics.htm#Exclusion.
Example:
loc eth0:192.168.1.0/24!192.168.1.4,192.168.1.16/28
In that example, the 'loc' zone is defined to be the subnet
192.168.1.0/24 interfacing via eth0 *except* for host 192.168.1.4
and hosts in the sub-network 192.168.1.16/28.
11) New "shorewall[-lite] show ip" and "shorewall[-lite] show routing"
commands have been added. The first produces the same output as "ip
addr ls". The second produces a report about your routing rules and
tables.
12) Beginning with this release, Shorewall and Shorewall Lite will
share common change logs and release notes.
13) In Shorewall versions prior to 3.3.2, multiple jumps to a '2all'
chain could be generated in succession.
Example from an earlier shorewall version:
gateway:~ # shorewall-lite show eth2_fwd
Shorewall Lite 3.3.2 Chains eth2_fwd at gateway - Thu Oct 19 08:54:37 PDT 2006
Counters reset Thu Oct 19 08:34:47 PDT 2006
Chain eth2_fwd (1 references)
pkts bytes target prot opt in out source destination
0 0 dynamic all -- * * 0.0.0.0/0 0.0.0.0/0 state INVALID,NEW
0 0 wifi2all all -- * eth0 0.0.0.0/0 0.0.0.0/0
0 0 wifi2all all -- * br0 0.0.0.0/0 0.0.0.0/0
0 0 wifi2all all -- * eth3 0.0.0.0/0 0.0.0.0/0
0 0 wifi2all all -- * tun+ 0.0.0.0/0 0.0.0.0/0
gateway:~ #
This redundancy may be eliminated by setting OPTIMIZE=1 in shorewall.conf.
gateway:~ # shorewall-lite show eth2_fwd
Shorewall Lite 3.3.3 Chains eth2_fwd at gateway - Thu Oct 19 09:15:24 PDT 2006
Counters reset Thu Oct 19 09:15:19 PDT 2006
Chain eth2_fwd (1 references)
pkts bytes target prot opt in out source destination
0 0 dynamic all -- * * 0.0.0.0/0 0.0.0.0/0 state INVALID,NEW
0 0 wifi2all all -- * * 0.0.0.0/0 0.0.0.0/0
gateway:~ #
Note that with OPTIMIZE=1, traffic destined for an
interface/Address that falls outside of all defined zones may now
be logged out of a '2all' chain rather than out of the FORWARD
chain.
The OPTIMIZE setting also controls the suppression of redundant
wildcard rules (those specifying "all" in the SOURCE or DEST
column). A wildcard rule is considered to be redundant when it
has the same ACTION and Log Level as the applicable policy.
Example:
/etc/shorewall/policy
#SOURCE DEST POLICY LEVEL
loc net ACCEPT
/etc/shorewall/rules
#ACTION SOURCE DEST PROTO DEST
# PORT(S)
...
ACCEPT all all icmp 8
OPTIMIZE=0
gateway:~ # shorewall show loc2net
Shorewall Lite 3.3.3 Chains loc2net at gateway - Thu Oct 26 07:55:03 PDT 2006
Counters reset Thu Oct 26 07:54:58 PDT 2006
Chain loc2net (1 references)
pkts bytes target prot opt in out source destination
...
0 0 DROP all -- * * !192.168.0.0/22 0.0.0.0/0
0 0 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0 icmp type 8
0 0 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0
gateway:~
OPTIMIZE=1
gateway:~ # shorewall show loc2net
Shorewall Lite 3.3.3 Chains loc2net at gateway - Thu Oct 26 07:57:12 PDT 2006
Counters reset Thu Oct 26 07:56:38 PDT 2006
Chain loc2net (1 references)
pkts bytes target prot opt in out source destination
...
0 0 DROP all -- * * !192.168.0.0/22 0.0.0.0/0
0 0 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0
gateway:~
If you really want a rule that duplicates the policy, follow the
action with "!":
#ACTION SOURCE DEST PROTO DEST
# PORT(S)
...
ACCEPT! all all icmp 8
14) IP Address ranges are now allowed in the drop, reject, allow and
logdrop shorewall[-lite] commands.
15) Previously, Shorewall has not attempted to undo the changes it has
made to the firewall's routing as a result of entries in
/etc/shorewall/providers and /etc/shorewall/routes. Beginning with
this release, Shorewall will attempt to undo these changes.
When Shorewall starts or is restarted and there are entries in
/etc/shorewall/providers, Shorewall will capture the contents
of /etc/shorewall/rt_tables and will restore that database when
Shorewall is stopped or restarted. Similarly, the default route
will be captured the first time that you [re]start Shorewall using
this version and will be restored under the following conditions:
a) shorewall stop
b) shorewall clear
c) shorewall restart or restore and there are no entries in
/etc/shorewall/providers.
Once the default route has been restored, Shorewall will delete
the saved copy so that it will once again be captured at the next
shorewall start or shorewall restore.
16) Shorewall no longer includes policy matches in its generated
ruleset when no IPSEC zones or IPSEC networks are defined (IPSEC
networks are defined using the 'ipsec' option in
/etc/shorewall/hosts).
17) The Makefile installed in /usr/share/shorewall/configfiles/ is now
the same one mentioned at
http://www.shorewall.net/CompiledPrograms.html.
Once the file is copied into an export directory, you modify the
setting of the HOST variable to match the name of the remote
firewall.
The default target is the "firewall" script so "make" compiles the
firewall script if any of the configuration files have
changed. "make install" builds "firewall" if necessary then
installs it on the remote firewall. "make capabilities" will
generate the "capabilities" file if that file doesn't exist. "make
save" will save the running configuration on the remote firewall.
18) Shorewall and Shorewall Lite now include the following manpages.
shorewall-accounting(5)
shorewall-actions(5)
shorewall-blacklist(5)
shorewall.conf(5)
shorewall-ecn(5)
shorewall-exclusion(5)
shorewall-hosts(5)
shorewall-interfaces(5)
shorewall-lite(8)
shorewall-maclist(5)
shorewall-masq(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-tcclasses(5)
shorewall-tcdevices(5)
shorewall-tcrules(5)
shorewall-template(5)
shorewall-tos(5)
shorewall-tunnels(5)
shorewall(8)
shorewall-zones(5)
Now that the manpages are in place, command-specific help has been
removed since it duplicates information in the man pages.
19) From the beginning, the Shorewall configuration files in
/etc/shorewall/ have contained documentary comments. While these
comments are useful, they present an upgrade problem. Beginning
with this release, these comments are removed from the
configuration files themselves and are replaced by the manpages
described in the preceding release note entry.
20) Shorewall now uses tc fwmark filters to classify packets for
traffic shaping when the DEVICE isn't an interface described in
/etc/shorewall/interfaces. This is in preparation for the upcoming
change to the way that --physdev-out works in iptables/Netfilter;
that change is now scheduled for kernel 2.6.20.
21) If your kernel and iptables have extended multiport support, then
Shorewall will use that support for the destination port when
generating rules from entries in the /etc/shorewall/tcrules file.
22) The 'safe-start' and 'safe-restart' command have been
improved. Both now accept an optional directory name; if supplied,
Shorewall will look first in that directory for configuration
files.
The commands have also been enhanced to only restore the
configuration once in the event of a failure. Previously, if there
was a current 'save' command in effect, then that configuration
would be restored on a failure and then the last-running
configuration would be restored.
23) The 'try' command has been reimplemented with new semantics.
If Shorewall is started then the firewall state is saved to a
temporary saved configuration (/var/lib/shorewall/.try). Next, if
Shorewall is currently started then a restart command is issued;
otherwise, a start command is performed. if an error occurs during
the compliation phase of the restart or start, the command
terminates without changing the Shorewall state. If an error occurs
during the restart phase, then a 'shorewall restore' is performed
using the saved configuration. If an error occurs during the start
phase, then Shorewall is cleared. If the start/restart succeeds
and a timeout is specified then a 'clear' or 'restore' is performed
after timeout seconds.
24) The syntax of the 'export' command has been made slightly
friendlier.
The old syntax:
export <directory1> [user@]system:[<directory2>]
It is now:
export <directory1> [user@]system[:<directory2>]
In other words, if you don't need to specify <directory2>, you may
omit the colon (":") following the system name.
The old syntax is still accepted -- that is, you can still
type:
export firewall2:
which is equivalent to
export firewall2
25) Shorewall commands may be speeded up slightly by using a
'capabilities' file. The 'capabilities' file was originally
designed for use with Shorewall Lite and records the
iptables/Netfilter features available on the target system.
To generate a capabilities file, execute the following command as
root:
shorewall show -f capabilities > /etc/shorewall/capabilities
When you install a new kernel and/or iptables, be sure to generate
a new capabilities file.
26) When syslogd is run with the -C option (which in some
implementations causes syslogd to log to an in-memory circular
buffer), /sbin/shorewall will now use the 'logread' command to read
the log from that buffer. This is for combatibility with OpenWRT.
27) There is now a ":T" qualifier in /etc/shorewall/tcrules which
causes the resulting rule to be inserted into the POSTROUTING
chain.
Problems Corrected in 3.4.0 Beta 1.
1) It is now possible to place entries in the IPSEC column of
/etc/shorewall/masq without having specified ipsec zones or hosts.
2) The /etc/shorewall/masq file is no longer ignored when the
/etc/shorewall/nat file is empty.
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