Shorewall 3.3.5 Note to users upgrading from Shorewall 3.0 or 3.3 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 If you have a file named /etc/shorewall/modules, please remove it. The default modules file is now located in /usr/share/shorewall/ (see the "Migration Considerations" below). Please see the "Migration Considerations" below for additional upgrade information. Problems Corrected in 3.3.5 1) Previously, if the last 'balance' provider was removed from /etc/shorewall/providers then "shorewall restart" would not restore the default route that was in place prior to "shorewall start". 2) Previously, restoration of routing was ignoring the "-n" option. Now such restoration only occurs if "-n" was not specified. Other Changes in 3.3.5. None. 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) Ensure correct operation. Default actions can also avoid common pitfalls like dropping connection requests on port 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: 1) In order to accomodate small embedded applications, Shorewall 3.3 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 3.3: - 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.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. - 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. - Only including the 'modules' file appropriate for the kernel in use. - Omitting all unused extension scripts. - Stripping the comments (except for copyright) from the various files. 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 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 length 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 2, that gives a maximum zone name length of 11. 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 attaching comments to Netfilter rules. Comments can be up to 255 bytes in length and are visible using the "shorewall show ", "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 the following 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. So by the time that COMMENT is processed, the "#" and everything after 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 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 policy match dir out pol none 0 0 wifi2all all -- * br0 0.0.0.0/0 0.0.0.0/0 policy match dir out pol none 0 0 wifi2all all -- * eth3 0.0.0.0/0 0.0.0.0/0 policy match dir out pol none 0 0 wifi2all all -- * tun+ 0.0.0.0/0 0.0.0.0/0 policy match dir out pol none 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) The lib.cli library has been added. It is distributed with both Shorewall and Shorewall Lite and contains the command-processing code that is common to both /sbin/shorewall and /sbin/shorewall-lite. 16) 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.