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Shorewall 3.2.0 Beta 5
Note to users upgrading from Shorewall 2.x or 3.0
Most problems associated with upgrades come from two causes:
- The user didn't read and follow the migration considerations in these
release notes.
- The user mis-handled the /etc/shorewall/shorewall.conf file during
upgrade. Shorewall is designed to allow the default behavior of
the product to evolve over time. To make this possible, the design
assumes that you will not replace your current shorewall.conf file
during upgrades. If you feel absolutely compelled to have the latest
comments and options in your shorewall.conf then you must proceed
carefully.
While you are at it, if you have a file named /etc/shorewall/rfc1918 then
please check that file. If it has addresses listed that are NOT in one of
these three ranges, then please rename the file to
/etc/shorewall/rfc1918.old.
10.0.0.0 - 10.255.255.255
172.16.0.0 - 172.31.255.255
192.168.0.0 - 192.168.255.255
Please see the "Migration Considerations" below for additional upgrade
information.
Problems Corrected in 3.2.0 Beta 5
1) On systems such as LEAF Bering that either don't have the 'mktemp' utility
or whose 'mktemp' cannot create a temporary directory, firewall compilation
failed with the message:
ERROR: No Interfaces Defined
after a shell error message indicating that the stripped interfaces
file in /tmp/shorewall-NNNN/ couldn't be opened.
Other changes in 3.2.0 Beta 5
None.
Migration Considerations:
1) If you are upgrading from Shorewall 2.x, it is essential that you read
the Shorewall 3.0.5 release notes:
http://www.shorewall.net/pub/shorewall/3.0/shorewall-3.0.5/releasenotes.txt
2) A number of macros have been split into two. The macros affected are:
IMAP LDAP NNTP POP3 SMTP
Each of these macros now handles only traffic on the native (plaintext)
port. There is a corresponding macro with S added to the end of the
name for the SSL version of the same protocol. Thus each macro results
in the insertion of only one port per invocation.
The Web macro has not been split, but two new macros, HTTP and HTTPS have
been created. The Web macro is deprecated in favour of these new macros,
and may be removed from future Shorewall releases.
These changes have been made to ensure no unexpected ports are opened due
to the use of macros.
3) In previous Shorewall releases, DNAT and REDIRECT rules supported a
special syntax for exclusion of a subnet from the effect of the rule.
Example:
Z2 is a subzone of Z1:
DNAT Z1!Z2 loc:192.168.1.4 ...
That feature has never worked correctly when Z2 is a dynamic zone.
Furthermore, now that Shorewall supports exclusion lists, the capability
is redundant since the above rule can now be written in the form:
DNAT Z1:!<list of exclusions> loc:192.168.1.4 ...
Beginning with Shorewall 3.2.0, the special exclusion syntax will no
longer be supported.
4) Important if you use the QUEUE target.
In the /etc/shorewall/rules file and in actions, you may now specify
'tcpsyn' in the PROTO column. 'tcpsyn' is equivalent to 'tcp' but also
requires that the SYN flag is set and the RST, FIN and ACK flags be
off ("--syn" is added to the iptables rule).
As part of this change, Shorewall no longer adds the "--syn" option
to TCP rules that specify QUEUE as their target.
5) Extension Scripts may require change
In previous releases, extension scripts were executed during [re]start
by using the Bourne Shell "." operator. In addition to executing commands
during [re]start, these scripts had to "save" the commands to be executed
during "shorewall restore".
This clumsiness has been eliminated in Shorewall 3.2. In Shorewall 3.2,
extension scripts are copied in-line into the compiled program and are
executed in-line during "start", "restart" and "restore".
This new approach has two implications for existing scripts.
a) It is no longer necessary to save the commands; so functions like
'save_command', 'run_and_save_command' and 'ensure_and_save_command'
need no longer be called. The generated program will contain
functions with these names:
save_command() - does nothing
run_and_save_command() - runs the passed command
ensure_and_save_command() - runs the passed command and
stops the firewall if the command
fails.
These functions should provide for transparent migration of
scripts that use them until you can get around to eliminating
their use completely.
b) When the extension script is copied into the compiled program, it
is indented to line up with the surrounding code. If you have 'awk'
installed on your system, the Shorewall compiler will correctly handle
line continuation (last character on the line = "\"). If you do not
have awk, it will not be possible to use line-continuation in your
extension scripts.
In no case is it possible to continue a quoted string over multiple lines
without having additional whitespace inserted into the string.
New Features:
1) Shorewall has always been very noisy (lots of messages). No longer.
You set the default level of verbosity using the VERBOSITY option in
shorewall.conf. If you don't set it (as would be the case of you use your
old shorewall.conf file) then VERBOSITY defaults to a value of 2 which is
the old default. A value of 1 suppresses some of the output (like the old
-q option did) while a value of 0 makes Shorewall almost silent. A value
of -1 suppresses all output except warning and error messages.
The value specified in the 3.2 shorewall.conf is 1. So you can make
Shorewall as verbose as previously using a single -v and you can make it
silent by using a single -q.
If the default is set at 2, you can still make a command silent by using
two "q"s (e.g., shorewall -qq restart).
In summary, each "q" subtracts one from VERBOSITY while each "v" adds one
to VERBOSITY.
The "shorewall show log", "shorewall logwatch" and "shorewall dump"
commands require VERBOSITY to be greater than or equal to 3 to display MAC
addresses.This is consistent with the previous implementation which
required a single -v to enable MAC display but means that if you set
VERBOSITY=0 in shorewall.conf, then you will need to include -vvv in
commands that display log records in order to have MACs displayed.
2) A new 'shorewall compile' command has been added.
shorewall compile [ -e ] [ -d <distro> ] [ <config directory> ] <script file>
where:
-e Allows the generated script to run
on a system without Shorewall installed.
Generates an error if the configuration uses
an option that would prevent the generated
script from running on a system other than
where the 'compile' command is running (see
additional consideration a) below).
-d <distro> Compile the script for execution on the
distribution specified by <distro>. Currently,
the supported distributions are:
suse
redhat (which includes Fedora Core and
CentOS).
debian
Note that specifying a distribution should
only be required if you intend to install
the compiled script in /etc/init.d on the
target system and the target system runs
a distribution different from the system
where you are doing your compiles.
Example:
shorewall compile -e -d redhat foo
Additional distributions are expected to be
supported shortly.
<config directory> Is an optional directory to be searched for
configuration files prior to those listed
in CONFIG_DIR in
/etc/shorewall/shorewall.conf.
<script file> Is the name of the output file.
The 'compile' command processes the configuration and generates a
script file which may then be executed (either directly or using the
'shorewall restore' command) to configure the firewall.
The generated script contains error checking and will terminate if an
important command fails. Before terminating:
a) The script will check for the existence of the restore script
specified by the RESTOREFILE variable in shorewall.conf. If that
restore script exists, it is executed.
b) If the restore script doesn't exist but Shorewall appears to be
installed on the system, the equivalent of an
"/sbin/shorewall stop" command is executed.
Some additional considerations:
a) It is possible to run 'compile' on one system and then run the
generated script on another system but there are certain
limitations.
1) A compatible version of Shorewall must be running on the remote
system unless you use the "-e" option when you compile the script.
Currently, "compatible" means Shorewall 3.1.5 or later.
2) The 'detectnets' interface option is not allowed.
3) You must supply the file /etc/shorewall/capabilities to provide
the compiler with knowledge of the capabilities of the system
where the script is to be run. The /etc/shorewall/capabilities
file included in this release includes instructions for its
use. Also, find information below about how to create the
file using the 'shorecap' program.
4) If your /etc/shorewall/params file contains code other than simple
assignment statements with contant values, then you should move
that code to /etc/shorewall/init. That way, the code will be
executed on the target system when the compiled script is run rather
than on the local system at compile time.
b) If you run the "shorewall compile" or "shorewall check" commands under
a user other than 'root', then you must supply
/etc/shorewall/capabilities.
c) To aid in building /etc/shorewall/capabilities, a 'shorecap' program
is provided. The program is installed in the /usr/share/shorewall/
directory.
The program can be copied to the target system and run there to
produce a capabilities file taylored for that system. The capabilities
file can then be copied to the local system where it can be used
when compiling firewall programs targeted for the remote system.
For instructions about running shorecap, see the comments at the
top of the program file (it's a simple shell script).
Compilation generates a complete program. This program is suitable for
installation into /etc/init.d and, when generated with the "-e" option,
can serve as your firewall on a system that doesn't even have Shorewall
installed.
The generated program supports the following commands:
<program> [ -q ] [ -v ] [ -n ] start
<program> [ -q ] [ -v ] [ -n ] stop
<program> [ -q ] [ -v ] [ -n ] clear
<program> [ -q ] [ -v ] [ -n ] restart
<program> [ -q ] [ -v ] [ -n ] status
<program> [ -q ] [ -v ] [ -n ] version
The options have the same meaning as they do with /sbin/shorewall
(see above).
The "shorewall start" and "shorewall restart" commands have been
rewritten to use compilation. They both compile a temporary program
then run it. This results in a slightly longer elapsed time than the
similar commands required under earlier versions of Shorewall but new
connections are blocked for a much smaller percentage of that time.
If an error is found during the compilation phase, /sbin/shorewall
terminates and the Shorewall state is unchanged.
Under Shorewall 3.1.5, "shorewall restart" takes roughly 16.5 seconds
on my firewall:
real 0m16.599s
user 0m6.292s
sys 0m9.885s
Of the elapsed 16.5 seconds, new connections are disabled less than
3.5 seconds. Here are some numbers for comparison:
A) shorewall restart (Shorewall 3.0.4)
real    0m17.540s
user    0m5.956s
sys     0m10.737s
B) ./foo restart # foo created using "shorewall compile"
real 0m3.297s
user 0m1.444s
sys 0m1.728s
C) shorewall restore (Shorewall 3.0.4) # Restores from file generated by
# "shorewall save"
real    0m1.164s
user    0m0.556s
sys     0m0.608s
D) shorewall restore (shorewall 3.1.5)
real 0m1.637s
user 0m0.728s
sys 0m0.584s
The time difference between B and C reflects the difference between
"iptables-restore" and multiple executions of "iptables". The time
difference between C and D results from the fact that the "restore"
command in Shorewall 3.1 runs the compiled program in a way that
turns all iptables commands into no-ops then invokes
iptables-restore. The system is a 1.4Ghz Celeron with 512MB RAM.
As a final part of this change, the "check" command now compiles the
current configuration and writes the compiled output to /dev/null. So
"check" performs all of the same checks that compile does. Note that
there is still no guarantee that the generated script won't encounter
run-time errors.
2) The /etc/shorewall/maclist file has a new column layout. The first column
is now DISPOSITION. This column determines what to do with matching
packets and can have the value ACCEPT or DROP (if MACLIST_TABLE=filter, it
can also contain REJECT). This change is upward compatible so your existing
maclist file can still be used.
ACCEPT, DROP and REJECT may be optionally followed by a log level to
cause the packet to be logged.
4) In macro files, you can now use the reserved words SOURCE and DEST
in the columns of the same names. When Shorewall expands the
macro, it will substitute the SOURCE from the macro invocation for
SOURCE and the DEST from the invocation for DEST. This allows you
to write macros that act in both directions (from source to destination
and from destination to source).
Example:
macro.FOO:
PARAM SOURCE DEST udp 500
PARAM DEST SOURCE udp 500
/etc/shorewall/rules:
FOO/ACCEPT fw net
Resulting rules:
ACCEPT fw net udp 500
ACCEPT net fw udp 500
This new feature has been used to implement the SMBBI macro.
SMBBI is the same as the SMB macro with the exception that
it passes SMB traffic in both directions whereas SMB only
passes that traffic in one direction.
5) In the /etc/shorewall/rules file and in actions, you may now specify
'tcp:syn' in the PROTO column. 'tcp:syn' is equivalent to 'tcp' but also
requires that the SYN flag is set and the RST, FIN and ACK flags be
off ("--syn" is added to the iptables rule).
As part of this change, Shorewall no longer adds the "--syn" option
to TCP rules that specify QUEUE as their target.
6) /sbin/shorewall now supports a "-t" option that causes all progress
messages to be timestamped.
Example (VERBOSITY=0 in shorewall.conf):
gateway:/etc/shorewall # shorewall -t restart
07:08:51 Compiling...
07:09:05 Shorewall configuration compiled to /var/lib/shorewall/.restart
07:09:05 Restarting Shorewall....
07:09:08 done.
gateway:/etc/shorewall #
7) A 'refreshed' extension script has been added -- it is executed after
"shorewall refresh" has finished.
8) Two new dynamic blacklisting commands have been added:
logdrop -- like 'drop' but causes the dropped packets to be logged.
logreject -- like 'reject' but causes the rejected packets to be
logged.
Packets are logged at the BLACKLIST_LOGLEVEL if one was specified at the
last "shorewall [re]start"; otherwise, they are logged at the 'info'
log level.
9) A new IMPLICIT_CONTINUE option has been added to shorewall.conf. When
this option is set to "Yes", it causes subzones to be treated differently
with respect to policies.
Subzones are defined by following their name with ":" and a list of parent
zones (in /etc/shorewall/zones). Normally, you want to have a set of
special rules for the subzone and if a connection doesn't match any of
those subzone-specific rules then you want the parent zone rules to be
applied. With IMPLICIT_CONTINUE=Yes, that happens automatically.
If IMPLICIT_CONTINUE=No or if IMPLICIT_CONTINUE is not set, then
subzones are not subject to this special treatment.
With IMPLICIT_CONTINUE=Yes, an implicit CONTINUE policy may be overridden
by including an explicit policy (one that does not specify "all" in either
the SOURCE or the DEST columns).
Example:
/etc/shorewall/zones:
par ipv4
chld:par ipv4
Traffic to/from the 'chld' zone will first pass through the applicable
'chld' rules and if none of those rules match then it will be passed through
the appropriate 'par' rules. If the connection request does not match
any of the 'par' rules then the relevant 'par' policy is applied.
If you want the fw->chld policy to be ACCEPT, simply add this entry to
/etc/shorewall/policy:
$FW chld ACCEPT
Traffic from all other zones to 'chld' will be subject to the implicit
CONTINUE policy.
10) Shorewall now includes support for explicit routing rules when the
/etc/shorewall/providers file is used. A new file, /etc/shorewall/rtrules
can be used to add routing rules based on packet source and/or
destination.
The file has the following columns:
SOURCE(optonal) An ip address (network or host) that
matches the source IP address in a packet.
May also be specified as an interface
name optionally followed by ":" and an
address. If the define 'lo' is specified,
the packet must originate from the firewall
itself.
DEST(optional) An ip address (network or host) that
matches the destination IP address in a packet.
If you choose to omit either SOURCE or DEST,
place "-" in the column. Note that you
may not omit both SOURCE and DEST.
PROVIDER The provider to route the traffic through.
May be expressed either as the provider name
or the provider number.
PRIORITY
The rule's priority which determines the order
in which the rules are processed.
1000-1999 Before Shorewall-generated
'MARK' rules
11000- 11999 After 'MARK' rules but before
Shorewall-generated rules for
provider interfaces.
26000-26999 After provider interface rules but
before 'default' rule.
Rules with equal priority are applied in
the order in which they appear in the file.
Example: You want all traffic coming in on eth1 to be routed to the ISP1
provider:
#PROVIDER PRIORITY SOURCE DEST
ISP1 1000 eth1
11) Prior to now, it has not been possible to use connection marking in
/etc/shorewall/tcrules if you have a multi-ISP configuration that uses the
'track' option.
Beginning with this release, you may now set HIGH_ROUTE_MARKS=Yes in
shorewall.conf to effectively divide the packet mark and connection mark
into two 8-byte mark fields.
When you do this:
a) The MARK field in the providers file must have a value that is
less than 65536 and that is a multiple of 256 (using hex
representation, the values are 0x0100-0xFF00 with the low-order
8 bits being zero).
b) You may only set those mark values in the PREROUTING chain.
c) Marks used for traffic shaping must still be in the range of 1-255
and may still not be set in the PREROUTING chain.
d) When you SAVE or RESTORE in tcrules, only the TC mark value is
saved or restored. Shorewall handles saving and restoring the
routing (provider) marks.
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