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
      default
      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.

      simplest
      The simplest rc file which does allow traffic to our services looks like
      e.g.:

       interfaces=eth0

       ips_eth0=default
       ip_eth0_default=192.168.26.27
       net_eth0_default=192.168.0.0/16

       services_eth0_default_tcp=local
       ports_eth0_default_tcp_local="0:65535"
       sources_eth0_default_tcp_local="0.0.0.0/0"

       services_eth0_default_udp=local
       ports_eth0_default_udp_local="0:65535"
       sources_eth0_default_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.

      realistic
      If you'd like to block traffic on wlan0 and allow traffic to ssh on your
      wired interface, and don't like to explicitly set your IPs in rc:

       # list of interfaces you'd like uruk to protect
       interfaces=eth0 wlan0

       . /lib/uruk/init/autodetect-ips

       # names for eth0's 2 IPv4 addresses
       ips_eth0="default dhcp"

       # allow access to our sshd on eth0's primary IP on tcp port 443
       # from anywhere
       services_eth0_default_tcp=ssh
       ports_eth0_default_tcp_ssh=443
       sources_eth0_default_tcp_ssh="0.0.0.0/0"

       # we get a static IPv4 via dhcp
       ip_eth0_dhcp=10.0.0.3
       net_eth0_dhcp=10./8

       services_eth0_dhcp_tcp=http
       ports_eth0_dhcp_tcp_http=http
       sources_eth0_dhcp_tcp_http=$net_eth0_dhcp

       # we leave services_wlan0_default_{tcp,udp} unset: don't allow any
       # incoming connections on wlan0's default IP

      autodetect-ips
      The script autodetect-ips --as used in the previous example-- looks  for
      files /etc/sysconfig/network-scripts/ifcfg-* (commonly found at e.g. Red
      Hat and Fedora systems) and /etc/network/interfaces (as  found  at  e.g.
      Debian  and Ubuntu systems), and, for each interface nic, and each found
      IPv4 and  IPv6  address  and  network,  sets  variables  ip_nic_default,
      ip6_nic_default,  net_nic_default  and  net6_nic_default . Then it calls
      ip(8) and adds any other found nic, ip and net triplets (for  IPv4  and,
      for IPv6, only addresses in scope "global").

      The  script autodetect-ips is useful if you'd like to share your rc file
      among different hosts.

      another example
      For an even more reasonable rc file, look at the well-commented  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 its default
      settings is safe too.

      allowing IPv6 tunneling
      In rc there is:

       rc_b=${etcdir}/proto_41

      while the file proto_41 reads

       $iptables -A INPUT -i ppp0 --protocol 41 --destination $ip_ppp0 -j ACCEPT

      This allows IP protocol 41, typically used for this kind of tunneling.

      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 targeted 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 /sbin/uruk

      this shows what is done, along with executing it.  (Like  an  uruk  '-v'
      option.)

      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) 2005, 2007, 2008, 2010, 2011, 2012, 2013 Joost  van  Baal-
      Ili <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-Ili <joostvb-uruk@mdcc.cx>



  uruk-rc 20130809                    9  2013                         uruk-rc(5)
