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Shorewall 3.9.8
----------------------------------------------------------------------------
R E L E A S E H I G H L I G H T S
----------------------------------------------------------------------------
1) This is the first Shorewall release that fully integrates the new
Shorewall-perl compiler. See the "New Features" section below.
2) You are now offered a choice as to which compiler(s) you install. In
3.9.2, there are the following packages:
- Shorewall ( common files )
- Shorewall-shell ( the shell-based compiler )
- Shorewall-perl (the Perl-based compiler )
You must install Shorewall and at least one of the compiler packages
(you may install them both).
Problems corrected in 3.9.8.
1) The commands "shorewall add/delete <interface> <zone>" no longer
case lots of error messages to be issued.
2) A port list in a SOURCE PORT(S) column now works when the DEST
PORT(S) list is empty.
3) A run-time error no longer occurs when an IP address is specified
in the GATEWAY column of /etc/shorewall/providers.
Other changes in Shorewall 3.9.8.
1) The "shorewall show zones" command now flags zone members that have
been added using "shorewall add" by preceding them with a plus sign
("+").
Example:
Shorewall 3.9.4 Zones at gateway - Mon May 14 07:48:16 PDT 2007
fw (firewall)
net (ipv4)
eth0:0.0.0.0/0
loc (ipv4)
br0:0.0.0.0/0
eth4:0.0.0.0/0
eth5:0.0.0.0/0
+eth1:0.0.0.0/0
dmz (ipv4)
eth3:0.0.0.0/0
vpn (ipv4)
tun+:0.0.0.0/0
In the above output, "eth1:0.0.0.0/0" was dynamically added to the
'loc' zone. As part of this change, "shorewall delete" will only
delete entries that have been added dynamically. In earlier
versions, any entry could be deleted although the ruleset was only
changed by deleting entries that had been added dynamically.
Migration Considerations:
1) You cannot simply upgrade your existing Shorewall package. You must
upgrade Shorewall *and* install one or both of the compilers.
If you attempt to upgrade using the RPM, you get this result:
gateway:~ # rpm -Uvh shorewall-3.9.2-1.noarch.rpm
error: Failed dependencies:
shorewall_compiler is needed by shorewall-3.9.2-1.noarch
gateway:~ #
You must either:
rpm -U shorewall-3.9.2.noarch.rpm shorewall-shell-3.9.2.noarch.rpm
or
rpm -U shorewall-3.9.2.noarch.rpm shorewall-perl-3.9.2.noarch.rpm
or
rpm -i shorewall-shell-3.9.2.noarch.rpm
rpm -U shorewall-3.9.2.noarch.rpm
or
rpm -i shorewall-perl-3.9.2.noarch.rpm
rpm -U shorewall-3.9.2.noarch.rpm
If you are upgrading using the tarball, you must install either
shorewall-shell or shorewall-perl before you upgrade
Shorewall. Otherwise, the install.sh script fails with:
ERROR: No Shorewall compiler is installed
The shorewall-shell and shorewall-perl packages are installed from
the tarball in the expected way; untar the package, and run the
install.sh script.
----------------------------------------------------------------------------
N E W F E A T U R E S
----------------------------------------------------------------------------
1) Shorewall-perl
This companion product to Shorewall 3.4.2 and later includes a complete
rewrite of the compiler in Perl.
I decided to make Shorewall-perl a separate product for several reasons:
a) Embedded applications are unlikely to adopt Shorewall-perl; even
Mini-Perl has a substantial disk and Ram footprint.
b) Because of the gross incompatibilities between the new compiler and the
old (see below), migration to the new compiler must be voluntary.
c) By allowing Shorewall-perl to co-exist with the current
Shorewall stable release (3.4), I'm hoping that the new compiler
will get more testing and validation than it would if I were to
package it with a new development version of Shorewall itself.
d) Along the same vein, I think that users will be more likely to
experiment with the new compiler if they can easily fall back to
the old one if things get sticky.
------------------------------------------------------------------------
T H E G O O D N E W S:
------------------------------------------------------------------------
a) The compiler has a small disk footprint.
b) The compiler is very fast.
c) The compiler generates a firewall script that uses iptables-restore;
so the script is very fast.
d) Use of the perl compiler is optional! The old slow clunky
Bourne-shell compiler is still available.
------------------------------------------------------------------------
T H E B A D N E W S:
------------------------------------------------------------------------
There are a number of incompatibilities between the Perl-based compiler
and the Bourne-shell one. Some of these will probably go away by first
official release but most will not.
a) The Perl-based compiler requires the following capabilities in your
kernel and iptables.
- addrtype match (may be relaxed later)
- multiport match (will not be relaxed)
These capabilities are in current distributions.
b) Now that Netfilter has features to deal reasonably with port lists,
I see no reason to duplicate those features in Shorewall. The
Bourne-shell compiler goes to great pain (in some cases) to
break very long port lists ( > 15 where port ranges in lists count
as two ports) into individual rules. In the new compiler, I'm
avoiding the ugliness required to do that. The new compiler just
generates an error if your list is too long. It will also produce
an error if you insert a port range into a port list and you don't
have extended multiport support.
c) BRIDGING=Yes is not supported. The kernel code necessary to
support this option was removed in Linux kernel 2.6.20.
d) The BROADCAST column in the interfaces file is essentially unused;
if you enter anything in this column but '-' or 'detect', you will
receive a warning. This will be relaxed if and when the addrtype
match requirement is relaxed.
e) Because the compiler is now written in Perl, your compile-time
extension scripts from earlier versions will no longer work.
Compile-time extension scripts are executed using the Perl
'eval `cat <file>`' mechanism. Be sure that each script returns a
'true' value; otherwise, the compiler will assume that the script
failed and will abort the compilation.
When a script is invoked, the $chainref scalar variable will hold a
reference to a chain table entry.
$chainref->{name} contains the name of the chain
$chainref->{table} holds the table name
To add a rule to the chain:
add_rule $chainref, <the rule>
Where
<the rule> is a scalar argument holding the rule text. Do
not include "-A <chain name>"
Example:
add_rule $chainref, '-j ACCEPT';
To insert a rule into the chain:
insert_rule $chainref, <rulenum>, <the rule>
The log_rule_limit function works like it does in the shell
compiler with two exceptions:
- You pass the chain reference rather than the name of
the chain.
- The commands are 'add' and 'insert' rather than '-A'
and '-I'.
- There is only a single "pass as-is to iptables"
argument (so you must quote that part).
Example:
log_rule_limit
'info' ,
$chainref ,
$chainref->{name},
'DROP' ,
'', #Limit
'' , #Log tag
'add';
f) The 'refresh' command is now synonymous with 'restart'.
g) Some run-time scripts will need to be changed to write their
iptables commands to file descriptor 3 in iptables-restore
format rather than running those commands.
maclog
Details to follow.
Some run-time scripts are simply eliminated because they no
longer make any sense under Shorewall-perl:
initdone - The these two scripts assumed a model where the
continue chains were built in parallel. In the
iptables-restore model, chains are built serially
within tables and tables are build serially.
refresh - The 'refresh' command is the same as 'restart'
refreshed
h) The /etc/shorewall/tos file now has zone-independent SOURCE and
DEST columns as do all other files except the rules and policy
files.
The SOURCE column may be one of the following:
[all:]<address>[,...]
[all:]<interface>[:<address>[,...]]
$FW[:<address>[,...]]
The DEST column may be one of the following:
[all:]<address>[,...]
[all:]<interface>[:<address>[,...]]
This is a permanent change. The old zone-based rules have never
worked right and this is a good time to replace them. I've tried
to make the new syntax cover the most common cases without
requiring change to existing files. In particular, it will
handle the tos file released with Shorewall 1.4 and earlier.
i) Shorewall is now out of the ipset load/reload business. With
scripts generated by the Perl-based Compiler, the Netfilter
ruleset is never cleared. That means that there is no
opportunity for Shorewall to load/reload your ipsets since that
cannot be done while there are any current rules using ipsets.
So:
i) Your ipsets must be loaded before Shorewall starts. You
are free to try to do that with the following code in
/etc/shorewall/start:
if [ "$COMMAND" = start ]; then
ipset -U :all: :all:
ipset -F
ipset -X
ipset -R < /my/ipset/contents
fi
The file '/my/ipset/contents' (not its real name of
course) will normally be produced using the ipset -S
command.
The above will work most of the time but will fail in a
'shorewall stop' - 'shorewall start' sequence if you
use ipsets in your routestopped file (see below).
ii) Your ipsets may not be reloaded until Shorewall is stopped
or cleared.
iii) If you specify ipsets in your routestopped file then
Shorewall must be cleared in order to reload your ipsets.
As a consequence, scripts generated by the Perl-based compiler
will ignore /etc/shorewall/ipsets and will issue a warning if
you set SAVE_IPSETS=Yes in shorewall.conf.
j) Because the configuration files (with the exception of
/etc/shorewall/params) are now processed by the Perl-based
compiler rather than by the shell, only the basic forms of Shell
expansion ($variable and ${variable}) are supported. The more
exotic forms such as ${variable:=default} are not
supported. Both variables defined in /etc/shorewall/params and
environmental variables (exported by the shell) can be used in
configuration files.
h) USE_ACTIONS=No is not supported. That option is intended to
minimize Shorewall's footprint in embedded applications. As a
consequence, Default Macros are not supported.
i) DELAYBLACKLISTLOAD=Yes is not supported. The entire ruleset is
atomically loaded with one execution of iptables-restore.
j) MAPOLDACTIONS=Yes is not supported. People should have converted
to using macros by now.
k) The pre Shorewall-3.0 format of the zones file is not supported;
neither is the /etc/shorewall/ipsec file.
l) BLACKLISTNEWONLY=No is not permitted with FASTACCEPT=Yes. This
combination doesn't work in previous versions of Shorewall so
the Perl-based compiler simply rejects it.
m) Shorewall-perl has a single rule generator that is used for all
rule-oriented files. So it is important that the syntax is
consistent between files.
With shorewall-shell, there is a special syntax in the SOURCE
column of /etc/shorewall/masq to designate "all traffic entering
the firewall on this interface except...".
Example:
#INTERFACE SOURCE ADDRESSES
eth0 eth1!192.168.4.9 ...
Shorewall-perl uses syntax that is consistent with the rest of
Shorewall:
#INTERFACE SOURCE ADDRESSES
eth0 eth1:!192.168.4.9 ...
2) An 'optional' option has been added to
/etc/shorewall/interfaces. When 'optional' is specified for an
interface, Shorewall will be silent when:
- a /proc/sys/net/ipv4/conf/ entry for the interface cannot be
modified (including for proxy ARP).
- The first address of the interface cannot be obtained.
I specify 'optional' on interfaces to Xen virtual machines that may
or may not be running when Shorewall is [re]started.
CAUTION: Use 'optional' at your own risk. If you [re]start
Shorewall when an 'optional' interface is not available and then do
a 'shorewall save', subsequent 'shorewall restore' and 'shorewall -f
start' operations will instantiate a ruleset that does not support
that interface, even if it is available at the time of the
restore/start.
3) The treatment of the following interface options has changed under
Shorewall-perl.
- arp_filter
- routefilter
- logmartians
- proxy_arp
- sourceroute
With the Shorewall-shell compiler, Shorewall resets these options
on all interfaces then sets the option on those interfaces
for which the option is defined in /etc/shorewall/interfaces.
Under Shorewall-perl, these options can be specified with the value
0 or 1 (e.g., proxy_arp=0). If no value is specified, the value 1
is assumed. Shorewall will modify only the setting of those
interfaces for which the option is specified and will set the
option to the given value.
A fatal compilation error is also generated if you specify one of
these options with a wildcard interface (one ending with '+').
4) Thanks to Paul Gear, an IPPServer macro has been added. Be sure to
read the comments in the macro file before trying to use this
macro.
5) The LOG_MARTIANS and ROUTE_FILTER options are now tri-valued.
Yes - Same as before
No - Same as before except that it applies regardless of
whether any interfaces have the logmartians/routefilter
option
Keep - Shorewall ignores the option entirely.
6) Eariler generations of Shorewall Lite required that remote root
login via ssh be enabled in order to use the 'load' and 'reload'
commands.
Beginning with this release, you may define an alternative means
for accessing the remote firewall system.
Two new options have been added to shorewall.conf:
RSH_COMMAND
RCP_COMMAND
The default values for these are as follows:
RSH_COMMAND: ssh ${root}@${system} ${command}
RCP_COMMAND: scp ${files} ${root}@${system}:${destination}
Shell variables that will be set when the commands are envoked are
as follows:
root - root user. Normally 'root' but may be overridden using
the '-r' option.
system - The name/IP address of the remote firewall system.
command - For RSH_COMMAND, the command to be executed on the
firewall system.
files - For RCP_COMMAND, a space-separated list of files to
be copied to the remote firewall system.
destination - The directory on the remote system that the files
are to be copied into.
7) The accounting, masq, rules and tos files now have a 'MARK' column
similar to the column of the same name in the tcrules file. This
column allows filtering by MARK and CONNMARK value.
8) SOURCE and DEST are now reserved zone names to avoid problems with
bi-directional macro definitions which use these as names as key
words.
9) Shorewall-perl now validates all IP addresses and addresses ranges
in rules. DNS names are resolved and an error is issued for any
name that cannot be resolved.
10) Shorewall-perl now checks configuration files for the presense of
characters that can cause problems if they are allowed into the
generated firewall script:
- Double Quotes. These are prohibited except in the
shorewall.conf and params files.
- Single Quotes. These are prohibited except in the
shorewall.conf and params files and in COMMENT lines.
- Single back quotes. These are prohibited except in the
shorewall.conf and params files.
- Backslash. Probibited except as the last character on a line to
denote line continuation.
11) Under Shorewall-perl, macros may now invoke other macros with the
restriction that such macros may not be invoked within an action
body.
When marcros are invoked recursively, the parameter passed to an
invocation are automatically propagated to lower level macros.
Macro invocations may be nested to a maximum level of 5.
----------------------------------------------------------------------------
P R E R E Q U I S I T E S
----------------------------------------------------------------------------
- Perl (I use Perl 5.8.8 but other versions should work fine)
- Perl Cwd Module
- Perl File::Basename Module
- Perl File::Temp Module
----------------------------------------------------------------------------
U S I N G T H E N E W C O M P I L E R
----------------------------------------------------------------------------
If you only install one compiler, then that compiler will be used.
If you install both compilers, then the compiler actually used depends
on the SHOREWALL_COMPILER setting in shorewall.conf.
The value of this new option can be either 'perl' or 'shell'.
If you add 'SHOREWALL_COMPILER=perl' to /etc/shorewall/shorewall.conf
then by default, the new compiler will be used on the system. If you
add it to shorewall.conf in a separate directory (such as a
Shorewall-lite export directory) then the new compiler will only be
used when you compile from that directory.
If you only install one compiler, it is suggested that you do not set
SHOREWALL_COMPILER.
If you install Shorewall-perl under Shorewall 3.9.2 or later, you can
select the compiler to use on the command line using the 'C option:
'-C shell' means use the shell compiler
'-C perl' means use the perl compiler
The -C option overrides the setting in shorewall.conf.
Example:
shorewall restart -C perl
Regardless of the setting of SHOREWALL_COMPILER, there is one change in
Shorewall operation that is triggered simply by installing
shorewall-perl. Your params file will be processed during compilation
with the shell's '-a' option which causes any variables that you set
or create in that file to be automatically exported. Since the params
file is processed before shorewall.conf, using -a insures that the
settings of your params variables are available to the new compiler
should its use be specified in shorewall.conf.
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