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524 lines
20 KiB
Plaintext
524 lines
20 KiB
Plaintext
Shorewall 3.2.0 Beta 6
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Note to users upgrading from Shorewall 2.x or 3.0
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Most problems associated with upgrades come from two causes:
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- The user didn't read and follow the migration considerations in these
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release notes.
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- The user mis-handled the /etc/shorewall/shorewall.conf file during
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upgrade. Shorewall is designed to allow the default behavior of
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the product to evolve over time. To make this possible, the design
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assumes that you will not replace your current shorewall.conf file
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during upgrades. If you feel absolutely compelled to have the latest
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comments and options in your shorewall.conf then you must proceed
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carefully.
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While you are at it, if you have a file named /etc/shorewall/rfc1918 then
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please check that file. If it has addresses listed that are NOT in one of
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these three ranges, then please rename the file to
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/etc/shorewall/rfc1918.old.
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10.0.0.0 - 10.255.255.255
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172.16.0.0 - 172.31.255.255
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192.168.0.0 - 192.168.255.255
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Please see the "Migration Considerations" below for additional upgrade
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information.
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Problems Corrected in 3.2.0 Beta 6
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1) Previously, if 'shorewall restart' was done out of an ip-up.local
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script, some of the utilities like 'tc' and 'ip6tables' were not
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on the PATH.
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2) In previous 3.2.0 releases, 'detectnets' in /etc/shorewall/interfaces
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produced an error message:
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ERROR: 'detectnets' not permitted with the -e run-line option
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even when the -e option had not been specified.
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Other changes in 3.2.0 Beta 6
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None.
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Migration Considerations:
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1) If you are upgrading from Shorewall 2.x, it is essential that you read
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the Shorewall 3.0.5 release notes:
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http://www.shorewall.net/pub/shorewall/3.0/shorewall-3.0.5/releasenotes.txt
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2) A number of macros have been split into two. The macros affected are:
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IMAP LDAP NNTP POP3 SMTP
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Each of these macros now handles only traffic on the native (plaintext)
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port. There is a corresponding macro with S added to the end of the
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name for the SSL version of the same protocol. Thus each macro results
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in the insertion of only one port per invocation.
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The Web macro has not been split, but two new macros, HTTP and HTTPS have
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been created. The Web macro is deprecated in favour of these new macros,
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and may be removed from future Shorewall releases.
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These changes have been made to ensure no unexpected ports are opened due
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to the use of macros.
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3) In previous Shorewall releases, DNAT and REDIRECT rules supported a
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special syntax for exclusion of a sub-zone from the effect of the rule.
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Example:
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Z2 is a subzone of Z1:
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DNAT Z1!Z2 loc:192.168.1.4 ...
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That feature has never worked correctly when Z2 is a dynamic zone.
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Furthermore, now that Shorewall supports exclusion lists, the capability
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is redundant since the above rule can now be written in the form:
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DNAT Z1:!<list of exclusions> loc:192.168.1.4 ...
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Beginning with Shorewall 3.2.0, the special exclusion syntax will no
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longer be supported.
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4) Important if you use the QUEUE target.
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In the /etc/shorewall/rules file and in actions, you may now specify
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'tcpsyn' in the PROTO column. 'tcpsyn' is equivalent to 'tcp' but also
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requires that the SYN flag is set and the RST, FIN and ACK flags be
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off ("--syn" is added to the iptables rule).
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As part of this change, Shorewall no longer adds the "--syn" option
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to TCP rules that specify QUEUE as their target.
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5) Extension Scripts may require change
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In previous releases, extension scripts were executed during [re]start
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by using the Bourne Shell "." operator. In addition to executing commands
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during [re]start, these scripts had to "save" the commands to be executed
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during "shorewall restore".
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This clumsiness has been eliminated in Shorewall 3.2. In Shorewall 3.2,
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extension scripts are copied in-line into the compiled program and are
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executed in-line during "start", "restart" and "restore".
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This new approach has two implications for existing scripts.
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a) It is no longer necessary to save the commands; so functions like
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'save_command', 'run_and_save_command' and 'ensure_and_save_command'
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need no longer be called. The generated program will contain
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functions with these names:
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save_command() - does nothing
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run_and_save_command() - runs the passed command
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ensure_and_save_command() - runs the passed command and
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stops the firewall if the command
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fails.
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These functions should provide for transparent migration of
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scripts that use them until you can get around to eliminating
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their use completely.
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b) When the extension script is copied into the compiled program, it
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is indented to line up with the surrounding code. If you have 'awk'
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installed on your system, the Shorewall compiler will correctly handle
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line continuation (last character on the line = "\"). If you do not
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have awk, it will not be possible to use line-continuation in your
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extension scripts.
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In no case is it possible to continue a quoted string over multiple lines
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without having additional whitespace inserted into the string.
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6) The "shorewall refresh" command no longer refreshes traffic shaping.
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Use "shorewall restart" instead if you need to reprocess the
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tcrules, tcdevices and tcclasses files.
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New Features:
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1) Shorewall has always been very noisy (lots of messages). No longer.
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You set the default level of verbosity using the VERBOSITY option in
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shorewall.conf. If you don't set it (as would be the case of you use your
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old shorewall.conf file) then VERBOSITY defaults to a value of 2 which
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results in behavior compatible with previous Shorewall versions.
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A value of 1 suppresses some of the output (like the old -q option did)
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while a value of 0 makes Shorewall almost silent. A value of -1
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suppresses all output except warning and error messages.
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The value specified in the 3.2 shorewall.conf is 1. So you can make
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Shorewall as verbose as previously using a single -v and you can make it
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silent by using a single -q.
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If the default is set at 2, you can still make a command silent by using
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two "q"s (e.g., shorewall -qq restart).
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In summary, each "q" subtracts one from VERBOSITY while each "v" adds one
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to VERBOSITY.
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The "shorewall show log", "shorewall logwatch" and "shorewall dump"
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commands require VERBOSITY to be greater than or equal to 3 to display MAC
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addresses.This is consistent with the previous implementation which
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required a single -v to enable MAC display but means that if you set
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VERBOSITY=0 in shorewall.conf, then you will need to include -vvv in
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commands that display log records in order to have MACs displayed.
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To make the display of MAC addresses let cumbersome, a '-m' option has
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been added to the "show" and logwatch commands:
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shorewall show -m log
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shorewall logwatch -m
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2) A new 'shorewall compile' command has been added.
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shorewall compile [ -e ] [ -d <distro> ] [ <config directory> ] <script file>
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where:
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-e Allows the generated script to run
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on a system without Shorewall installed.
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Generates an error if the configuration uses
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an option that would prevent the generated
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script from running on a system other than
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where the 'compile' command is running (see
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additional consideration a) below).
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-d <distro> Compile the script for execution on the
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distribution specified by <distro>. Currently,
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the supported distributions are:
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suse
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redhat (which includes Fedora Core and
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CentOS).
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debian
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Note that specifying a distribution should
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only be required if you intend to install
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the compiled script in /etc/init.d on the
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target system and the target system runs
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a distribution different from the system
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where you are doing your compiles.
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Example:
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shorewall compile -e -d redhat foo
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Additional distributions are expected to be
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supported shortly.
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<config directory> Is an optional directory to be searched for
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configuration files prior to those listed
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in CONFIG_DIR in
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/etc/shorewall/shorewall.conf.
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<script file> Is the name of the output file.
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The 'compile' command processes the configuration and generates a
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script file which may then be executed (either directly or using the
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'shorewall restore' command) to configure the firewall.
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The generated script contains error checking and will terminate if an
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important command fails. Before terminating:
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a) The script will check for the existence of the restore script
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specified by the RESTOREFILE variable in shorewall.conf. If that
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restore script exists, it is executed.
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b) If the restore script doesn't exist but Shorewall appears to be
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installed on the system, the equivalent of an
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"/sbin/shorewall stop" command is executed.
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Some additional considerations:
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a) It is possible to run 'compile' on one system and then run the
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generated script on another system but there are certain
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limitations.
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1) A compatible version of Shorewall must be running on the remote
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system unless you use the "-e" option when you compile the script.
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Currently, "compatible" means Shorewall 3.1.5 or later.
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2) The 'detectnets' interface option is not allowed.
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3) You must supply the file /etc/shorewall/capabilities to provide
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the compiler with knowledge of the capabilities of the system
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where the script is to be run. The /etc/shorewall/capabilities
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file included in this release includes instructions for its
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use. Also, find information below about how to create the
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file using the 'shorecap' program.
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4) If your /etc/shorewall/params file contains code other than simple
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assignment statements with contant values, then you should move
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that code to /etc/shorewall/init. That way, the code will be
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executed on the target system when the compiled script is run rather
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than on the local system at compile time.
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b) If you run the "shorewall compile" or "shorewall check" commands under
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a user other than 'root', then you must supply
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/etc/shorewall/capabilities.
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c) To aid in building /etc/shorewall/capabilities, a 'shorecap' program
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is provided. The program is installed in the /usr/share/shorewall/
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directory.
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The program can be copied to the target system and run there to
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produce a capabilities file taylored for that system. The capabilities
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file can then be copied to the local system where it can be used
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when compiling firewall programs targeted for the remote system.
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For instructions about running shorecap, see the comments at the
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top of the program file (it's a simple shell script).
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Compilation generates a complete program. This program is suitable for
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installation into /etc/init.d and, when generated with the "-e" option,
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can serve as your firewall on a system that doesn't even have Shorewall
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installed.
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The generated program supports the following commands:
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<program> [ -q ] [ -v ] [ -n ] start
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<program> [ -q ] [ -v ] [ -n ] stop
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<program> [ -q ] [ -v ] [ -n ] clear
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<program> [ -q ] [ -v ] [ -n ] restart
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<program> [ -q ] [ -v ] [ -n ] status
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<program> [ -q ] [ -v ] [ -n ] version
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The options have the same meaning as they do with /sbin/shorewall
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(see above).
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The "shorewall start" and "shorewall restart" commands have been
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rewritten to use compilation. They both compile a temporary program
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then run it. This results in a slightly longer elapsed time than the
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similar commands required under earlier versions of Shorewall but new
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connections are blocked for a much smaller percentage of that time.
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If an error is found during the compilation phase, /sbin/shorewall
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terminates and the Shorewall state is unchanged.
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Under Shorewall 3.1.5, "shorewall restart" takes roughly 16.5 seconds
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on my firewall:
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real 0m16.599s
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user 0m6.292s
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sys 0m9.885s
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Of the elapsed 16.5 seconds, new connections are disabled less than
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3.5 seconds. Here are some numbers for comparison:
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A) shorewall restart (Shorewall 3.0.4)
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real 0m17.540s
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user 0m5.956s
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sys 0m10.737s
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B) ./foo restart # foo created using "shorewall compile"
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real 0m3.297s
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user 0m1.444s
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sys 0m1.728s
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C) shorewall restore (Shorewall 3.0.4) # Restores from file generated by
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# "shorewall save"
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real 0m1.164s
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user 0m0.556s
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sys 0m0.608s
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D) shorewall restore (shorewall 3.1.5)
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real 0m1.637s
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user 0m0.728s
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sys 0m0.584s
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The time difference between B and C reflects the difference between
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"iptables-restore" and multiple executions of "iptables". The time
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difference between C and D results from the fact that the "restore"
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command in Shorewall 3.1 runs the compiled program in a way that
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turns all iptables commands into no-ops then invokes
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iptables-restore. The system is a 1.4Ghz Celeron with 512MB RAM.
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As a final part of this change, the "check" command now compiles the
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current configuration and writes the compiled output to /dev/null. So
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"check" performs all of the same checks that compile does. Note that
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there is still no guarantee that the generated script won't encounter
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run-time errors.
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2) The /etc/shorewall/maclist file has a new column layout. The first column
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is now DISPOSITION. This column determines what to do with matching
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packets and can have the value ACCEPT or DROP (if MACLIST_TABLE=filter, it
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can also contain REJECT). This change is upward compatible so your existing
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maclist file can still be used.
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ACCEPT, DROP and REJECT may be optionally followed by a log level to
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cause the packet to be logged.
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4) In macro files, you can now use the reserved words SOURCE and DEST
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in the columns of the same names. When Shorewall expands the
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macro, it will substitute the SOURCE from the macro invocation for
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SOURCE and the DEST from the invocation for DEST. This allows you
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to write macros that act in both directions (from source to destination
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and from destination to source).
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Example:
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macro.FOO:
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PARAM SOURCE DEST udp 500
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PARAM DEST SOURCE udp 500
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/etc/shorewall/rules:
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FOO/ACCEPT fw net
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Resulting rules:
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ACCEPT fw net udp 500
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ACCEPT net fw udp 500
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This new feature has been used to implement the SMBBI macro.
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SMBBI is the same as the SMB macro with the exception that
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it passes SMB traffic in both directions whereas SMB only
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passes that traffic in one direction.
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5) In the /etc/shorewall/rules file and in actions, you may now specify
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'tcp:syn' in the PROTO column. 'tcp:syn' is equivalent to 'tcp' but also
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requires that the SYN flag is set and the RST, FIN and ACK flags be
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off ("--syn" is added to the iptables rule).
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As part of this change, Shorewall no longer adds the "--syn" option
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to TCP rules that specify QUEUE as their target.
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6) /sbin/shorewall now supports a "-t" option that causes all progress
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messages to be timestamped.
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Example (VERBOSITY=0 in shorewall.conf):
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gateway:/etc/shorewall # shorewall -t restart
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07:08:51 Compiling...
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07:09:05 Shorewall configuration compiled to /var/lib/shorewall/.restart
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07:09:05 Restarting Shorewall....
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07:09:08 done.
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gateway:/etc/shorewall #
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7) A 'refreshed' extension script has been added -- it is executed after
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"shorewall refresh" has finished.
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8) Two new dynamic blacklisting commands have been added:
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logdrop -- like 'drop' but causes the dropped packets to be logged.
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logreject -- like 'reject' but causes the rejected packets to be
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logged.
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Packets are logged at the BLACKLIST_LOGLEVEL if one was specified at the
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last "shorewall [re]start"; otherwise, they are logged at the 'info'
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log level.
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9) A new IMPLICIT_CONTINUE option has been added to shorewall.conf. When
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this option is set to "Yes", it causes subzones to be treated differently
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with respect to policies.
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Subzones are defined by following their name with ":" and a list of parent
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zones (in /etc/shorewall/zones). Normally, you want to have a set of
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special rules for the subzone and if a connection doesn't match any of
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those subzone-specific rules then you want the parent zone rules to be
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applied. With IMPLICIT_CONTINUE=Yes, that happens automatically.
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If IMPLICIT_CONTINUE=No or if IMPLICIT_CONTINUE is not set, then
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subzones are not subject to this special treatment.
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With IMPLICIT_CONTINUE=Yes, an implicit CONTINUE policy may be overridden
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by including an explicit policy (one that does not specify "all" in either
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the SOURCE or the DEST columns).
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Example:
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/etc/shorewall/zones:
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par ipv4
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chld:par ipv4
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Traffic to/from the 'chld' zone will first pass through the applicable
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'chld' rules and if none of those rules match then it will be passed through
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the appropriate 'par' rules. If the connection request does not match
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any of the 'par' rules then the relevant 'par' policy is applied.
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If you want the fw->chld policy to be ACCEPT, simply add this entry to
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/etc/shorewall/policy:
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$FW chld ACCEPT
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Traffic from all other zones to 'chld' will be subject to the implicit
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CONTINUE policy.
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10) Shorewall now includes support for explicit routing rules when the
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/etc/shorewall/providers file is used. A new file,
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/etc/shorewall/route_rules can be used to add routing rules based on
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packet source and/or destination.
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The file has the following columns:
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SOURCE(optonal) An ip address (network or host) that
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matches the source IP address in a packet.
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May also be specified as an interface
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name optionally followed by ":" and an
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address. If the define 'lo' is specified,
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the packet must originate from the firewall
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itself.
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DEST(optional) An ip address (network or host) that
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matches the destination IP address in a packet.
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If you choose to omit either SOURCE or DEST,
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place "-" in the column. Note that you
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may not omit both SOURCE and DEST.
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PROVIDER The provider to route the traffic through.
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May be expressed either as the provider name
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or the provider number.
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PRIORITY
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The rule's priority which determines the order
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in which the rules are processed.
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1000-1999 Before Shorewall-generated
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'MARK' rules
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11000- 11999 After 'MARK' rules but before
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Shorewall-generated rules for
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provider interfaces.
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26000-26999 After provider interface rules but
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before 'default' rule.
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Rules with equal priority are applied in
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the order in which they appear in the file.
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Example: You want all traffic coming in on eth1 to be routed to the ISP1
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provider:
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#PROVIDER PRIORITY SOURCE DEST
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ISP1 1000 eth1
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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.
|