Bering-uClibc 5.x - User Guide - IPv6 Networking - Configure Shorewall6
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Contents
Introduction
Beginning with Bering-uClibc 4.x Package shorwall6.lrp is provided as configuration utility for the IPv6 firewall. shorwall6.lrp is an official variant of the IPv4 shorwall.lrp and is supported by the same team.
Note: The full name "Shorewall" was abbreviated to "shorwall" in order to comply with the 8 character filename length limit for MS-DOS floppy disks, hence the package file is shorwall.lrp. The name of the Shorewall6 package, shorwall6.lrp, is based on the name of the Shorewall package even though the 8 character filename length limit is no longer in effect.
In general, configuration of Shorewall6 is equivalent to configuration of Shorewall, so refer to the Shorewall chapter of this guide. A simple setup is described below. However, note the following differences:
- There are far fewer macros defined specifically for Shorewall6 than for Shorewall (in other words far fewer matches for
/usr/share/shorewall6/macro.*than for/usr/share/shorewall/macro.*)but all of the Shorewall(4) macros can be used for Shorewall6. Where both files are present (e.g. for mDNS) the Shorewall6 macro takes priority.
ICMP is rather more important for IPv6 than for IPv4, and an IPv6 network will not function unless at least some ICMP packet types are enabled. RFC 4890 defines "Recommendations for Filtering ICMPv6 Messages in Firewalls" and these recommendations are implemented as standard within Shorewall6. Refer to file /usr/share/shorewall6/action.AllowICMPs for more details.
Important: If you are running both Shorewall and Shorewall6 (rather than only Shorewall6) you may need to make a modification to the Shorewall configuration otherwise Shorewall6 will be stopped whenever Shorewall is restarted.
In file /etc/shorewall/shorewall.conf ensure that DISABLE_IPV6 is set to No (which is the default setting).
A small sample setup
The following setup will establish a firewall for your IPV6 router, that rejects all traffic initiated anywhere on the Internet to your router and LAN, but allows any traffic from your LAN to the Net. It also allows any traffic from your router/firewall to the LAN, but rejects traffic from your router/firewall to the Internet. So it's the easiest setup with a standard low-level protection for your LAN. (Note: The sample setup is based on a IPv6 tunnel to SiXXS.)
Configure your Zones
The /etc/shorewall6/zones file declares your network zones. You specify the hosts in each zone through entries in /etc/shorewall6/interfaces.
############################################################################### #ZONE TYPE OPTIONS IN OUT # OPTIONS OPTIONS fw firewall net ipv6 loc ipv6
Configure your Interfaces
The /etc/shorewall6/interfaces file serves to define the firewall's network interfaces to shorewall6. The order of entries in this file is not significant in determining zone composition.
############################################################################### #ZONE INTERFACE ANYCAST OPTIONS net sixxs detect loc eth1 detect
(It is assumed that your SiXXS tunnel interface is named sixxs; you may need to change, to fit your setup.)
Configure your Policy
The file /etc/shorewall6/policy defines the high-level policy for connections between zones defined in /etc/shorewall6/zones.
############################################################################### #SOURCE DEST POLICY LOG LIMIT: CONNLIMIT: # LEVEL BURST MASK fw loc ACCEPT loc net ACCEPT all all REJECT INFO
Important: If you change any of the shorewall6 parameters, remember to save your configuration!
Logfiles
With Bering-uClibc 5.x Shorewall6-related messages are written to two different logfiles:
- Shorewall6 startup messages are written to file
/var/log/shorewall6-init.log- This is because that file is specified as STARTUP_LOG in
/etc/shorewall6/shorewall6.conf
- This is because that file is specified as STARTUP_LOG in
- Any messages from the Linux kernel "Netfilter" code which contain the string "Shorewall" and relate to IPv6 addresses are written to file
/var/log/shorewall6.log- This is controlled by the entries in file
/etc/syslog-ng/syslog-ng.conf
- This is controlled by the entries in file
In addition, the logfile rotation logic defined in file /etc/lrp.conf means that /var/log/shorewall6.log gets renamed to /var/log/shorewall6.log.0 and then /var/log/shorewall6.log.1.gz etc. on a daily basis.
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