uruk-rc(5)                       FILE FORMATS                       uruk-rc(5)



  NAME
      uruk-rc - uruk resource file, defining access policy

  SYNOPSIS
      /etc/uruk/rc

  DESCRIPTION
      rc is a shell script snippet, sourced in uruk by /bin/sh.

      rc lists IP addresses, allowed to use services.

  EXAMPLES
      The  simplest  valid  rc file is the empty file. This rc file blocks all
      TCP and UDP connection attempts to services on our  host:  this  is  the
      default behaviour.  The simplest rc file which does allow traffic to our
      services looks like e.g.:

      interfaces=eth0

      ip_eth0=192.168.26.27
      net_eth0=192.168.0.0/16

      services_eth0_tcp=local
      ports_eth0_tcp_local="0:65535"
      sources_eth0_tcp_local="0.0.0.0/0"

      services_eth0_udp=local
      ports_eth0_udp_local="0:65535"
      sources_eth0_udp_local="0.0.0.0/0"

      This rc file allows all IPv4 UDP and TCP traffic from publicly  routable
      IPs  to eth0's IP.  For a more reasonable rc file, look at the well-com-
      mented example rc file in /usr/share/doc/uruk/examples/rc.

  HOOKS
      Uruk offers hooks for inserting your own code between  iptables  invoca-
      tions.  Examples will show the usefulness of these hooks.

      allowing broadcasts
      In rc, there is:

       rc_b=$etcdir/bootp

      while the file bootp reads

       iptables -A INPUT -m state --state NEW -i eth0 \
         --protocol udp --destination-port bootps -j ACCEPT

      .  This enables one to add rules for packets with broadcast addresses in
      their destination. (Uruk has no support for this in its regular rc.)

      allowing non-matching returntraffic
      In rc there is:

       rc_d=$etcdir/dns

      while the file dns reads

        for source in 10.5.0.27 10.56.0.40
        do
          $iptables -A INPUT -i eth0 --protocol udp \
            --source "$source" --source-port domain \
            --destination "$ip_eth0" \
            --destination-port 30000: -j ACCEPT
        done

      This allows one to allow (return)traffic, disregarding the state.  (Uruk
      has no support for this in its regular rc.)

      allowing NAT
      In rc there is:

       rc_a=${etcdir}/nat

      while the file nat reads

        $iptables -t nat -A POSTROUTING \
          --out-interface eth0 -j SNAT \
          --to-source $ip_eth0

      This  allows  Network  Address  Translation.  However,  beware! Like all
      extensive use of hooks, this will break the  uruk-save  script.  If  you
      make sure your active iptables rules are wiped, and invoke uruk manually
      to load new rules, you're safe. Using the init-script with it's  default
      settings is safe too.

      allowing any traffic on an interface
      In rc there is:

       interfaces_unprotect="lo eth2"

      This  allows any traffic on eth2 (and on lo, the default), including any
      ICMP packets and packets from any source address.

      using multiple hooks at one entry point in the main uruk process
      In case rc_a, rc_b, ... , or rc_i does not have a file as its value, but
      a  directory,  all  files  matching  "$rc_x"/*.rc will get sourced. This
      helps configuration management in complex situations involving  lots  of
      uruk configuration files for lots of hosts.

      See  the  section  "THE GORY DETAILS: uruk INTERNALS" in uruk(8) (or the
      uruk source) to find out which hook (there are hooks rc_a, rc_b,  ...  ,
      rc_i) to use.

  NETWORK INTERFACES WITH MULTIPLE IP ADDRESSES
      Uruk  supports situations where a network interface has more than one IP
      address attached. Variables ips_nic and bcasts_nic are used for this.

      If ips_nic is set, e.g. like

       ips_eth0="ip0 ip1 ip2"

      we assume multiple (three in this example) IPs are assigned to eth0.  If
      this variable is not set only one IP is supported on eth0.

      In multiple-IP mode, IP addresses are listed as e.g.

       ip_eth0_ip0="137.56.247.16"

      (If  you're used to the Linux ifconfig(8) output, you could use the name
      ip1 for eth0:1, and ip0 for eth0.)   The  ports,  services  and  sources
      variables look like e.g.

       services_eth0_ip2_tcp=local
       ports_eth0_ip2_tcp_local=smtp
       sources_eth0_ip2_tcp_local=$localnet

      and, similarly,

       net_eth0_ip1=192.168.0.0/16

      Furthermore, for dropping broadcast packets, specify e.g.

       bcasts_eth0="ip0 ip2"     # yes, possibly a subset of ips_eth0
       bcast_eth0_ip0="10.0.0.255"
       bcast_eth0_ip2="10.0.255.255"

      The  interfaces_nocast variable holds things like eth0 and eth1, like in
      single-IP-per-nic mode.

  LOGGING AND DEBUGGING
      Uruk has support for logging network packets, and for debugging the uruk
      script.

      Logging
      By  default,  uruk  logs  denied  packets.  This is adjustable using the
      loglevel variable. The settings are:

      o
        "zero":  be  silent;  do  not  log  any  packet.  rc   file   features
        loglevel=10.
      o
        "low":  log denied packets, which are targetted at one of our IPs.  rc
        file features loglevel=30.
      o
        "medium": log denied  non-broadcast  packets.  This  is  the  default:
        loglevel is unset or rc file features loglevel=50.
      o
        "fascist": log all packets. rc file features loglevel=90.

      Debugging
      To debug the uruk script, invoke uruk as

       sh -x /usr/sbin/uruk

      this  shows  what  is  done, along with executing it. (Like an uruk '-v'
      option.)  (Alternatively, add "set -x" to your rc file.)

      If you'd rather prefer not to execute, but just watch what would've been
      done, invoke uruk as

       URUK_IPTABLES='echo iptables' URUK_IP6TABLES='echo ip6tables' uruk

      (Like  an uruk '-n' option.) If you have this statement set, you can run
      uruk under a non-priviliged user account.

      If you'd like to test a new rc file before installing it, run  something
      like:


        URUK_CONFIG=/path/to/new/uruk/rc/file uruk

      Of course, all these tweaks can be combined.

  VARIABLES
      The uruk script honors the following variables in rc files:

      o
        "version" Uruk version compatibility of this rc file
      o
        "loglevel"
      o
        "iptables" Full pathname of iptables executable.
      o
        "ip6tables" Full pathname of ip6tables executable.
      o
        "interfaces" List of network interfaces.
      More variables are available. For now, you'll have to take a look at the
      example rc file in /usr/share/doc/uruk/examples/rc for more details.

  ENVIRONMENT VARIABLES
      See uruk(8) for a list of honored environment variables.

  FILES
      /etc/uruk/rc

  SEE ALSO
      A well-commented example rc file is in  /usr/share/doc/uruk/examples/rc.
      And see uruk(8), uruk-save(8).

  COPYRIGHT
      Copyright  (C)  2003  Stichting  LogReport  Foundation  logreport@logre-
      port.org;    Copyright    (C)    2003,    2004    Tilburg     University
      http://www.uvt.nl/;  Copyright (C) 2003, 2004, 2005, 2010 Joost van Baal
      <joostvb-uruk@mdcc.cx>

      This program is free software: you can redistribute it and/or modify  it
      under  the  terms  of the GNU General Public License as published by the
      Free Software Foundation, either version 3 of the License, or  (at  your
      option) any later version.

      This  program  is  distributed  in  the hope that it will be useful, but
      WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABIL-
      ITY  or  FITNESS  FOR  A  PARTICULAR PURPOSE. See the GNU General Public
      License for more details.

      You should have received a copy of the GNU General Public License  along
      with this program. If not, see http://www.gnu.org/licenses/.

  AUTHOR
      Joost van Baal <joostvb-uruk@mdcc.cx>



  uruk-rc 20120530                  30 mai 2012                       uruk-rc(5)
