shorewall_code/docs/kernel.xml

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  <!--$Id$-->

  <articleinfo>
    <title>Kernel Configuration</title>

    <authorgroup>
      <author>
        <firstname>Tom</firstname>

        <surname>Eastep</surname>
      </author>
    </authorgroup>

    <pubdate><?dbtimestamp format="Y/m/d"?></pubdate>

    <copyright>
      <year>2001-2006</year>

      <holder>Thomas M. Eastep</holder>
    </copyright>

    <legalnotice>
      <para>Permission is granted to copy, distribute and/or modify this
      document under the terms of the GNU Free Documentation License, Version
      1.2 or any later version published by the Free Software Foundation; with
      no Invariant Sections, with no Front-Cover, and with no Back-Cover
      Texts. A copy of the license is included in the section entitled
      <quote><ulink url="GnuCopyright.htm">GNU Free Documentation
      License</ulink></quote>.</para>
    </legalnotice>
  </articleinfo>

  <note>
    <para>For information regarding configuring and building GNU/Linux
    kernels, see <ulink
    url="http://www.kernelnewbies.org">http://www.kernelnewbies.org</ulink>.</para>
  </note>

  <section id="Network">
    <title>Network Options Configuration</title>

    <para>Here's a screen shot of my Network Options Configuration:<graphic
    align="center" fileref="images/netopts.jpg" /></para>

    <para>While not all of the options that I've selected are required, they
    should be sufficient for most applications. Here's an excerpt from the
    corresponding .config file (Note: If you are running a kernel older than
    2.4.17, be sure to select CONFIG_NETLINK and CONFIG_RTNETLINK):</para>

    <blockquote>
      <programlisting>#
 # Networking options
 #
 CONFIG_PACKET=y
 # CONFIG_PACKET_MMAP is not set
 # CONFIG_NETLINK_DEV is not set
 CONFIG_NETFILTER=y
 # CONFIG_NETFILTER_DEBUG is not set
 CONFIG_FILTER=y
 CONFIG_UNIX=y
 CONFIG_INET=y
 CONFIG_IP_MULTICAST=y
 CONFIG_IP_ADVANCED_ROUTER=y
 CONFIG_IP_MULTIPLE_TABLES=y
 CONFIG_IP_ROUTE_FWMARK=y
 CONFIG_IP_ROUTE_NAT=y
 CONFIG_IP_ROUTE_MULTIPATH=y
 CONFIG_IP_ROUTE_TOS=y
 CONFIG_IP_ROUTE_VERBOSE=y
 # CONFIG_IP_ROUTE_LARGE_TABLES is not set
 # CONFIG_IP_PNP is not set
 CONFIG_NET_IPIP=y
 CONFIG_NET_IPGRE=y
 # CONFIG_NET_IPGRE_BROADCAST is not set
 # CONFIG_IP_MROUTE is not set
 # CONFIG_ARPD is not set
 CONFIG_INET_ECN=y
 CONFIG_SYN_COOKIES=y</programlisting>
    </blockquote>
  </section>

  <section id="Netfilter">
    <title>Netfilter Configuration</title>

    <para>Here's a screen shot of my Netfilter configuration:<graphic
    align="center" fileref="images/menuconfig1.jpg" /></para>

    <para>Note that I have built everything I need as modules. You can also
    build everything into your kernel but if you want to be able to deal with
    FTP running on a non-standard port then you <emphasis
    role="bold">must</emphasis> modularize FTP Protocol support.</para>

    <para>Here's the corresponding part of my .config file:</para>

    <blockquote>
      <programlisting>#
#&nbsp;&nbsp; IP: Netfilter Configuration
#
CONFIG_IP_NF_CONNTRACK=m
CONFIG_IP_NF_FTP=m
CONFIG_IP_NF_AMANDA=m
CONFIG_IP_NF_TFTP=m
# CONFIG_IP_NF_IRC is not set
# CONFIG_IP_NF_QUEUE is not set
CONFIG_IP_NF_IPTABLES=m
CONFIG_IP_NF_MATCH_LIMIT=m
CONFIG_IP_NF_MATCH_MAC=m
CONFIG_IP_NF_MATCH_PKTTYPE=m
CONFIG_IP_NF_MATCH_MARK=m
CONFIG_IP_NF_MATCH_MULTIPORT=m
CONFIG_IP_NF_MATCH_TOS=m
CONFIG_IP_NF_MATCH_ECN=m
CONFIG_IP_NF_MATCH_DSCP=m
CONFIG_IP_NF_MATCH_AH_ESP=m
CONFIG_IP_NF_MATCH_LENGTH=m
# CONFIG_IP_NF_MATCH_TTL is not set
CONFIG_IP_NF_MATCH_TCPMSS=m
CONFIG_IP_NF_MATCH_HELPER=m
CONFIG_IP_NF_MATCH_STATE=m
CONFIG_IP_NF_MATCH_CONNTRACK=m
CONFIG_IP_NF_MATCH_UNCLEAN=m
# CONFIG_IP_NF_MATCH_OWNER is not set
CONFIG_IP_NF_FILTER=m
CONFIG_IP_NF_TARGET_REJECT=m
# CONFIG_IP_NF_TARGET_MIRROR is not set
CONFIG_IP_NF_NAT=m
CONFIG_IP_NF_NAT_NEEDED=y
CONFIG_IP_NF_TARGET_MASQUERADE=m
CONFIG_IP_NF_TARGET_REDIRECT=m
CONFIG_IP_NF_NAT_AMANDA=m
CONFIG_IP_NF_NAT_LOCAL=y
# CONFIG_IP_NF_NAT_SNMP_BASIC is not set
CONFIG_IP_NF_NAT_FTP=m
CONFIG_IP_NF_NAT_TFTP=m
CONFIG_IP_NF_MANGLE=m
CONFIG_IP_NF_TARGET_TOS=m
CONFIG_IP_NF_TARGET_ECN=m
CONFIG_IP_NF_TARGET_DSCP=m
CONFIG_IP_NF_TARGET_MARK=m
CONFIG_IP_NF_TARGET_LOG=m
CONFIG_IP_NF_TARGET_ULOG=m
CONFIG_IP_NF_TARGET_TCPMSS=m
CONFIG_IP_NF_ARPTABLES=m
CONFIG_IP_NF_ARPFILTER=m
# CONFIG_IP_NF_COMPAT_IPCHAINS is not set
# CONFIG_IP_NF_COMPAT_IPFWADM is not set</programlisting>
    </blockquote>
  </section>

  <section id="Netfilter-2.6">
    <title>Kernel 2.6 Netfilter Options</title>

    <para>Here's a screenshot of my modularized 2.6 Kernel config (Navigation:
    Device Drivers → Networking Support → Networking Options → Network Packet
    Filtering (replaces ipchains) → IP: Netfilter configuration):</para>

    <graphic align="center" fileref="images/netfilter2.6.png" valign="middle" />

    <para>Here is the corresponding part of the .config file:</para>

    <blockquote>
      <programlisting>CONFIG_IP_NF_CONNTRACK=m
CONFIG_IP_NF_FTP=m
CONFIG_IP_NF_IRC=m
CONFIG_IP_NF_TFTP=m
CONFIG_IP_NF_AMANDA=m
CONFIG_IP_NF_QUEUE=m
CONFIG_IP_NF_IPTABLES=m
CONFIG_IP_NF_MATCH_LIMIT=m
CONFIG_IP_NF_MATCH_IPRANGE=m
CONFIG_IP_NF_MATCH_MAC=m
CONFIG_IP_NF_MATCH_PKTTYPE=m
CONFIG_IP_NF_MATCH_MARK=m
CONFIG_IP_NF_MATCH_MULTIPORT=m
CONFIG_IP_NF_MATCH_TOS=m
CONFIG_IP_NF_MATCH_RECENT=m
CONFIG_IP_NF_MATCH_ECN=m
CONFIG_IP_NF_MATCH_DSCP=m
CONFIG_IP_NF_MATCH_AH_ESP=m
CONFIG_IP_NF_MATCH_LENGTH=m
CONFIG_IP_NF_MATCH_TTL=m
CONFIG_IP_NF_MATCH_TCPMSS=m
CONFIG_IP_NF_MATCH_HELPER=m
CONFIG_IP_NF_MATCH_STATE=m
CONFIG_IP_NF_MATCH_CONNTRACK=m
CONFIG_IP_NF_MATCH_OWNER=m
CONFIG_IP_NF_MATCH_PHYSDEV=m
CONFIG_IP_NF_FILTER=m
CONFIG_IP_NF_TARGET_REJECT=m
CONFIG_IP_NF_NAT=m
CONFIG_IP_NF_NAT_NEEDED=y
CONFIG_IP_NF_TARGET_MASQUERADE=m
CONFIG_IP_NF_TARGET_REDIRECT=m
CONFIG_IP_NF_TARGET_NETMAP=m
CONFIG_IP_NF_TARGET_SAME=m
CONFIG_IP_NF_NAT_LOCAL=y
CONFIG_IP_NF_NAT_SNMP_BASIC=m
CONFIG_IP_NF_NAT_IRC=m
CONFIG_IP_NF_NAT_FTP=m
CONFIG_IP_NF_NAT_TFTP=m
CONFIG_IP_NF_NAT_AMANDA=m
CONFIG_IP_NF_MANGLE=m
CONFIG_IP_NF_TARGET_TOS=m
CONFIG_IP_NF_TARGET_ECN=m
CONFIG_IP_NF_TARGET_DSCP=m
CONFIG_IP_NF_TARGET_MARK=m
CONFIG_IP_NF_TARGET_CLASSIFY=m
CONFIG_IP_NF_TARGET_LOG=m
CONFIG_IP_NF_TARGET_ULOG=m
CONFIG_IP_NF_TARGET_TCPMSS=m
# CONFIG_IP_NF_ARPTABLES is not set
# CONFIG_IP_NF_COMPAT_IPCHAINS is not set
# CONFIG_IP_NF_COMPAT_IPFWADM is not set
# CONFIG_IP_NF_RAW is not set
CONFIG_IP_NF_MATCH_ADDRTYPE=m
# CONFIG_IP_NF_MATCH_REALM is not set
CONFIG_IP6_NF_QUEUE=m
CONFIG_IP6_NF_IPTABLES=m
CONFIG_IP6_NF_MATCH_LIMIT=m
CONFIG_IP6_NF_MATCH_MAC=m
CONFIG_IP6_NF_MATCH_RT=m
CONFIG_IP6_NF_MATCH_OPTS=m
CONFIG_IP6_NF_MATCH_FRAG=m
CONFIG_IP6_NF_MATCH_HL=m
CONFIG_IP6_NF_MATCH_MULTIPORT=m
CONFIG_IP6_NF_MATCH_OWNER=m
CONFIG_IP6_NF_MATCH_MARK=m
CONFIG_IP6_NF_MATCH_IPV6HEADER=m
CONFIG_IP6_NF_MATCH_AHESP=m
CONFIG_IP6_NF_MATCH_LENGTH=m
CONFIG_IP6_NF_MATCH_EUI64=m
CONFIG_IP6_NF_FILTER=m
CONFIG_IP6_NF_TARGET_LOG=m
CONFIG_IP6_NF_MANGLE=m
CONFIG_IP6_NF_TARGET_MARK=m
# CONFIG_IP6_NF_RAW is not set
CONFIG_DECNET_NF_GRABULATOR=m
CONFIG_BRIDGE_NF_EBTABLES=m
</programlisting>
    </blockquote>
  </section>

  <section id="Kernel-2.6.16">
    <title>Kernel 2.6.16 and Later Netfilter Options</title>

    <para>Here's a screenshot of my modularized 2.6.16 Kernel config
    (Navigation: Networking → Networking Options → Network Packet Filtering
    (replaces ipchains) → Core Netfilter configuration):</para>

    <graphic align="center" fileref="images/kernel-2.6.16-1.png" />

    <para>Note that is is particularly important to select "Netfilter Xtables
    support (required for ip_tables).</para>

    <para>Here's a screenshot of the IP Netfilter config (Navigation:
    Networking → Networking Options → Network Packet Filtering (replaces
    ipchains) → IP: Netfilter configuration):</para>

    <graphic align="center" fileref="images/kernel-2.6.16-2.png" />

    <para>Here is the corresponding part of the .config file:</para>

    <blockquote>
      <programlisting>#
# Core Netfilter Configuration
#
CONFIG_NETFILTER_NETLINK=m
CONFIG_NETFILTER_NETLINK_QUEUE=m
CONFIG_NETFILTER_NETLINK_LOG=m
CONFIG_NETFILTER_XTABLES=m
CONFIG_NETFILTER_XT_TARGET_CLASSIFY=m
CONFIG_NETFILTER_XT_TARGET_CONNMARK=m
CONFIG_NETFILTER_XT_TARGET_MARK=m
CONFIG_NETFILTER_XT_TARGET_NFQUEUE=m
CONFIG_NETFILTER_XT_TARGET_NOTRACK=m
CONFIG_NETFILTER_XT_MATCH_COMMENT=m
CONFIG_NETFILTER_XT_MATCH_CONNBYTES=m
CONFIG_NETFILTER_XT_MATCH_CONNMARK=m
CONFIG_NETFILTER_XT_MATCH_CONNTRACK=m
CONFIG_NETFILTER_XT_MATCH_DCCP=m
CONFIG_NETFILTER_XT_MATCH_HELPER=m
CONFIG_NETFILTER_XT_MATCH_LENGTH=m
CONFIG_NETFILTER_XT_MATCH_LIMIT=m
CONFIG_NETFILTER_XT_MATCH_MAC=m
CONFIG_NETFILTER_XT_MATCH_MARK=m
CONFIG_NETFILTER_XT_MATCH_PHYSDEV=m
CONFIG_NETFILTER_XT_MATCH_PKTTYPE=m
CONFIG_NETFILTER_XT_MATCH_REALM=m
CONFIG_NETFILTER_XT_MATCH_SCTP=m
CONFIG_NETFILTER_XT_MATCH_STATE=m
CONFIG_NETFILTER_XT_MATCH_STRING=m
CONFIG_NETFILTER_XT_MATCH_TCPMSS=m

#
# IP: Netfilter Configuration
#
CONFIG_IP_NF_CONNTRACK=m
CONFIG_IP_NF_CT_ACCT=y
CONFIG_IP_NF_CONNTRACK_MARK=y
CONFIG_IP_NF_FTP=m
CONFIG_IP_NF_IRC=m
CONFIG_IP_NF_TFTP=m
CONFIG_IP_NF_AMANDA=m
CONFIG_IP_NF_PPTP=m
CONFIG_IP_NF_QUEUE=m
CONFIG_IP_NF_IPTABLES=m
CONFIG_IP_NF_MATCH_IPRANGE=m
CONFIG_IP_NF_MATCH_MULTIPORT=m
CONFIG_IP_NF_MATCH_TOS=m
CONFIG_IP_NF_MATCH_RECENT=m
CONFIG_IP_NF_MATCH_ECN=m
CONFIG_IP_NF_MATCH_DSCP=m
CONFIG_IP_NF_MATCH_AH_ESP=m
CONFIG_IP_NF_MATCH_TTL=m
CONFIG_IP_NF_MATCH_OWNER=m
CONFIG_IP_NF_MATCH_ADDRTYPE=m
CONFIG_IP_NF_MATCH_HASHLIMIT=m
CONFIG_IP_NF_MATCH_POLICY=m
CONFIG_IP_NF_FILTER=m
CONFIG_IP_NF_TARGET_REJECT=m
CONFIG_IP_NF_TARGET_LOG=m
CONFIG_IP_NF_TARGET_ULOG=m
CONFIG_IP_NF_TARGET_TCPMSS=m
CONFIG_IP_NF_NAT=m
CONFIG_IP_NF_NAT_NEEDED=y
CONFIG_IP_NF_TARGET_MASQUERADE=m
CONFIG_IP_NF_TARGET_REDIRECT=m
CONFIG_IP_NF_TARGET_NETMAP=m
CONFIG_IP_NF_TARGET_SAME=m
CONFIG_IP_NF_NAT_IRC=m
CONFIG_IP_NF_NAT_FTP=m
CONFIG_IP_NF_NAT_TFTP=m
CONFIG_IP_NF_NAT_AMANDA=m
CONFIG_IP_NF_NAT_PPTP=m
CONFIG_IP_NF_MANGLE=m
CONFIG_IP_NF_TARGET_TOS=m
CONFIG_IP_NF_TARGET_ECN=m
CONFIG_IP_NF_TARGET_DSCP=m
CONFIG_IP_NF_TARGET_TTL=m
CONFIG_IP_NF_RAW=m
CONFIG_IP_NF_ARPTABLES=m
CONFIG_IP_NF_ARPFILTER=m
CONFIG_IP_NF_ARP_MANGLE=m
</programlisting>
    </blockquote>
  </section>

  <section id="v2.6.20">
    <title>Kernel 2.6.20 and Later Netfilter Options</title>

    <para>Beginning with kernel 2.6.20, the Netfilter kernel configuration was
    completely changed. It is split into "Core Netfilter Configuration" and
    "IP Netfilter Configuration". The next graphic shows how I have configured
    the Core options -- these are the standard Ubuntu settings.</para>

    <para>The next two graphics show the Core Configuration settings - these
    are the standard Ubuntu setting with the exception of CONNTRACK Target
    support (Ubuntu inexplicably includes conntrack match support but not
    CONNTRACK target support). The two graphics show mostly the same
    information but the configuration menu is slignly larger than my display
    so I captured it in two images.<graphic align="center"
    fileref="images/kernel-2.6.20-1.png" /><graphic align="center"
    fileref="images/kernel-2.6.20-2.png" />The next graphic shows the IP
    Netfilter Configuration -- these are the standard Ubuntu settions.<graphic
    align="center" fileref="images/kernel-2.6.20-3.png" />Here is the
    corresponding CONFIG file exerpt.<programlisting>CONFIG_NETFILTER_XT_TARGET_CLASSIFY=m
CONFIG_NETFILTER_XT_TARGET_CONNMARK=m
CONFIG_NETFILTER_XT_TARGET_DSCP=m
CONFIG_NETFILTER_XT_TARGET_MARK=m
CONFIG_NETFILTER_XT_TARGET_NFQUEUE=m
CONFIG_NETFILTER_XT_TARGET_NFLOG=m
# CONFIG_NETFILTER_XT_TARGET_NOTRACK is not set
CONFIG_NETFILTER_XT_TARGET_SECMARK=m
CONFIG_NETFILTER_XT_TARGET_CONNSECMARK=m
CONFIG_NETFILTER_XT_MATCH_COMMENT=m
CONFIG_NETFILTER_XT_MATCH_CONNBYTES=m
CONFIG_NETFILTER_XT_MATCH_CONNMARK=m
CONFIG_NETFILTER_XT_MATCH_CONNTRACK=m
CONFIG_NETFILTER_XT_MATCH_DCCP=m
CONFIG_NETFILTER_XT_MATCH_DSCP=m
CONFIG_NETFILTER_XT_MATCH_ESP=m
CONFIG_NETFILTER_XT_MATCH_HELPER=m
CONFIG_NETFILTER_XT_MATCH_LENGTH=m
CONFIG_NETFILTER_XT_MATCH_LIMIT=m
CONFIG_NETFILTER_XT_MATCH_MAC=m
CONFIG_NETFILTER_XT_MATCH_MARK=m
CONFIG_NETFILTER_XT_MATCH_POLICY=m
CONFIG_NETFILTER_XT_MATCH_MULTIPORT=m
CONFIG_NETFILTER_XT_MATCH_PHYSDEV=m
CONFIG_NETFILTER_XT_MATCH_PKTTYPE=m
CONFIG_NETFILTER_XT_MATCH_QUOTA=m
CONFIG_NETFILTER_XT_MATCH_REALM=m
CONFIG_NETFILTER_XT_MATCH_SCTP=m
CONFIG_NETFILTER_XT_MATCH_STATE=m
CONFIG_NETFILTER_XT_MATCH_STATISTIC=m
CONFIG_NETFILTER_XT_MATCH_STRING=m
CONFIG_NETFILTER_XT_MATCH_TCPMSS=m
CONFIG_NETFILTER_XT_MATCH_HASHLIMIT=m
CONFIG_NF_CONNTRACK_SUPPORT=y
CONFIG_NF_CONNTRACK_ENABLED=m
# CONFIG_IP_NF_CONNTRACK_SUPPORT is not set
CONFIG_NF_CONNTRACK=m
CONFIG_NF_CT_ACCT=y
CONFIG_NF_CONNTRACK_MARK=y
CONFIG_NF_CONNTRACK_SECMARK=y
CONFIG_NF_CONNTRACK_EVENTS=y
CONFIG_NF_CT_PROTO_GRE=m
CONFIG_NF_CT_PROTO_SCTP=m
CONFIG_NF_CONNTRACK_AMANDA=m
CONFIG_NF_CONNTRACK_FTP=m
CONFIG_NF_CONNTRACK_H323=m
CONFIG_NF_CONNTRACK_IRC=m
CONFIG_NF_CONNTRACK_NETBIOS_NS=m
CONFIG_NF_CONNTRACK_PPTP=m
CONFIG_NF_CONNTRACK_SIP=m
CONFIG_NF_CONNTRACK_TFTP=m
CONFIG_NF_CT_NETLINK=m
CONFIG_NF_CONNTRACK_IPV4=m
CONFIG_NF_CONNTRACK_PROC_COMPAT=y
CONFIG_IP_NF_QUEUE=m
CONFIG_IP_NF_IPTABLES=m
CONFIG_IP_NF_MATCH_IPRANGE=m
CONFIG_IP_NF_MATCH_TOS=m
CONFIG_IP_NF_MATCH_RECENT=m
CONFIG_IP_NF_MATCH_ECN=m
CONFIG_IP_NF_MATCH_AH=m
CONFIG_IP_NF_MATCH_TTL=m
CONFIG_IP_NF_MATCH_OWNER=m
CONFIG_IP_NF_MATCH_ADDRTYPE=m
CONFIG_IP_NF_FILTER=m
CONFIG_IP_NF_TARGET_REJECT=m
CONFIG_IP_NF_TARGET_LOG=m
CONFIG_IP_NF_TARGET_ULOG=m
CONFIG_IP_NF_TARGET_TCPMSS=m
CONFIG_NF_NAT=m
CONFIG_NF_NAT_NEEDED=y
CONFIG_IP_NF_TARGET_MASQUERADE=m
CONFIG_IP_NF_TARGET_REDIRECT=m
CONFIG_IP_NF_TARGET_NETMAP=m
CONFIG_IP_NF_TARGET_SAME=m
CONFIG_NF_NAT_SNMP_BASIC=m
CONFIG_NF_NAT_PROTO_GRE=m
CONFIG_NF_NAT_FTP=m
CONFIG_NF_NAT_IRC=m
CONFIG_NF_NAT_TFTP=m
CONFIG_NF_NAT_AMANDA=m
CONFIG_NF_NAT_PPTP=m
CONFIG_NF_NAT_H323=m
CONFIG_NF_NAT_SIP=m
CONFIG_IP_NF_MANGLE=m
CONFIG_IP_NF_TARGET_TOS=m
CONFIG_IP_NF_TARGET_ECN=m
CONFIG_IP_NF_TARGET_TTL=m
CONFIG_IP_NF_TARGET_CLUSTERIP=m
CONFIG_IP_NF_RAW=m
CONFIG_IP_NF_ARPTABLES=m
CONFIG_IP_NF_ARPFILTER=m
CONFIG_IP_NF_ARP_MANGLE=m
</programlisting></para>

    <para></para>
  </section>

  <section>
    <title>Minimal Configuration using Kernel 2.6.20 and later</title>

    <para>Massimo Burcheri has contributed this minimal configuration which is
    suitable for securing a laptop or desktop. It is strictly a "no-frills"
    configuration and represents the minimum that will work with Shorewall
    when using only the very basic Shorewall features described in the <ulink
    url="standalone.htm">one-interface quickstart guide</ulink>.<graphic
    align="center" fileref="images/2.6.21_conf_01.png" /><graphic
    align="center" fileref="images/2.6.21_conf_02.png" /><graphic
    align="center" fileref="images/2.6.21_conf_03.png" /></para>
  </section>
</article>