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    Rozcestník

    Dotaz: Firewall a bridge

    8.4.2010 13:03 firewall
    Firewall a bridge
    Přečteno: 318×
    Mam vygenerovany firewall z http://easyfwgen.morizot.net/gen/index.php a potreboval by som pravidla rozsirit o bridge postaveny na eth1. Chcem tam povolit celu prevadzku, pokial co firewall na eth0 (povolene ssh a ftp) bude normalne pracovat.

    Odpovědi

    8.4.2010 14:18 Filip Jirsák | skóre: 68 | blog: Fa & Bi
    Rozbalit Rozbalit vše Re: Firewall a bridge
    A dotaz? Pokud chcete vědět, jak to integrovat do stávajícího firewallu, bude potřeba, abyste popsal stávající konfiguraci (asi ten vygenerovaný soubor přiložit jako přílohu). Jinak mi tedy připadá k ničemu nechat si vygenerovat nějakou konfiguraci firewallu, které nerozumíte, podle mne z toho bude víc škody, než užitku. Když sítím nerozumíte, je vám firewall stejně k ničemu, protože s největší pravděpodobností bude děravý a naopak bude bránit oprávněné komunikaci.
    8.4.2010 20:20 firewall
    Rozbalit Rozbalit vše Re: Firewall a bridge

    #!/bin/sh
    SYSCTL="/sbin/sysctl -w"
    IPT="/sbin/iptables"
    IPTS="/sbin/iptables-save"
    IPTR="/sbin/iptables-restore"

    INET_IFACE="eth0"
    INET_IFACE1="vlan73"
    INET_IFACE2="eth1"
    INET_IFACE3="br0"
    INET_IFACE4="vnet0"

    LO_IFACE="lo"
    LO_IP="127.0.0.1"
    if [ "$1" = "save" ]
    then
    echo -n "Saving firewall to /etc/sysconfig/iptables ... "
    $IPTS > /etc/sysconfig/iptables
    echo "done"
    exit 0
    elif [ "$1" = "restore" ]
    then
    echo -n "Restoring firewall from /etc/sysconfig/iptables ... "
    $IPTR < /etc/sysconfig/iptables
    echo "done"
    exit 0
    fi

    if [ "$SYSCTL" = "" ]
    then
    echo "1" > /proc/sys/net/ipv4/tcp_syncookies
    else
    $SYSCTL net.ipv4.tcp_syncookies="1"
    fi

    if [ "$SYSCTL" = "" ]
    then
    echo "1" > /proc/sys/net/ipv4/conf/all/rp_filter
    else
    $SYSCTL net.ipv4.conf.all.rp_filter="1"
    fi

    if [ "$SYSCTL" = "" ]
    then
    echo "1" > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts
    else
    $SYSCTL net.ipv4.icmp_echo_ignore_broadcasts="1"
    fi

    if [ "$SYSCTL" = "" ]
    then
    echo "0" > /proc/sys/net/ipv4/conf/all/accept_source_route
    else
    $SYSCTL net.ipv4.conf.all.accept_source_route="0"
    fi

    if [ "$SYSCTL" = "" ]
    then
    echo "1" > /proc/sys/net/ipv4/conf/all/secure_redirects
    else
    $SYSCTL net.ipv4.conf.all.secure_redirects="1"
    fi

    if [ "$SYSCTL" = "" ]
    then
    echo "1" > /proc/sys/net/ipv4/conf/all/log_martians
    else
    $SYSCTL net.ipv4.conf.all.log_martians="0"
    fi


    ###############################################################################
    #
    # Flush Any Existing Rules or Chains
    #

    echo "Flushing Tables ..."

    # Reset Default Policies
    $IPT -P INPUT ACCEPT
    $IPT -P FORWARD ACCEPT
    $IPT -P OUTPUT ACCEPT
    $IPT -t nat -P PREROUTING ACCEPT
    $IPT -t nat -P POSTROUTING ACCEPT
    $IPT -t nat -P OUTPUT ACCEPT
    $IPT -t mangle -P PREROUTING ACCEPT
    $IPT -t mangle -P OUTPUT ACCEPT

    # Flush all rules
    $IPT -F
    $IPT -t nat -F
    $IPT -t mangle -F

    # Erase all non-default chains
    $IPT -X
    $IPT -t nat -X
    $IPT -t mangle -X

    if [ "$1" = "stop" ]
    then
    echo "Firewall completely flushed!  Now running with no firewall."
    exit 0
    fi

    ###############################################################################
    #
    # Rules Configuration
    #

    ###############################################################################
    #
    # Filter Table
    #
    ###############################################################################

    # Set Policies

    $IPT -P INPUT DROP
    $IPT -P OUTPUT DROP
    $IPT -P FORWARD DROP

    ###############################################################################
    #
    # User-Specified Chains
    #
    # Create user chains to reduce the number of rules each packet
    # must traverse.

    echo "Create and populate custom rule chains ..."

    # Create a chain to filter INVALID packets

    $IPT -N bad_packets

    # Create another chain to filter bad tcp packets

    $IPT -N bad_tcp_packets

    # Create separate chains for icmp, tcp (incoming and outgoing),
    # and incoming udp packets.

    $IPT -N icmp_packets

    # Used for UDP packets inbound from the Internet
    $IPT -N udp_inbound

    # Used to block outbound UDP services from internal network
    # Default to allow all
    $IPT -N udp_outbound

    # Used to allow inbound services if desired
    # Default fail except for established sessions
    $IPT -N tcp_inbound

    # Used to block outbound services from internal network
    # Default to allow all
    $IPT -N tcp_outbound

    ###############################################################################
    #
    # Populate User Chains
    #

    # bad_packets chain
    #
    $IPT -A bad_packets -p ALL -m state --state INVALID -j DROP

    # Then check the tcp packets for additional problems
    $IPT -A bad_packets -p tcp -j bad_tcp_packets

    # All good, so return
    $IPT -A bad_packets -p ALL -j RETURN

    # bad_tcp_packets chain
    #
    # All tcp packets will traverse this chain.
    # Every new connection attempt should begin with
    # a syn packet.  If it doesn't, it is likely a
    # port scan.  This drops packets in state
    # NEW that are not flagged as syn packets.

    $IPT -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j DROP
    $IPT -A bad_tcp_packets -p tcp --tcp-flags ALL NONE -j DROP
    $IPT -A bad_tcp_packets -p tcp --tcp-flags ALL ALL -j DROP
    $IPT -A bad_tcp_packets -p tcp --tcp-flags ALL FIN,URG,PSH -j DROP
    $IPT -A bad_tcp_packets -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j DROP
    $IPT -A bad_tcp_packets -p tcp --tcp-flags SYN,RST SYN,RST -j DROP
    $IPT -A bad_tcp_packets -p tcp --tcp-flags SYN,FIN SYN,FIN -j DROP

    # All good, so return
    $IPT -A bad_tcp_packets -p tcp -j RETURN

    # icmp_packets chain
    #
    # This chain is for inbound (from the Internet) icmp packets only.
    # Type 8 (Echo Request) is not accepted by default
    # Enable it if you want remote hosts to be able to reach you.
    # 11 (Time Exceeded) is the only one accepted
    # that would not already be covered by the established
    # connection rule.  Applied to INPUT on the external interface.
    #
    # See: http://www.ee.siue.edu/~rwalden/networking/icmp.html
    # for more info on ICMP types.
    #
    # Note that the stateful settings allow replies to ICMP packets.
    # These rules allow new packets of the specified types.

    # ICMP packets should fit in a Layer 2 frame, thus they should
    # never be fragmented.  Fragmented ICMP packets are a typical sign
    $IPT -A icmp_packets --fragment -p ICMP -j DROP

    # Echo - uncomment to allow your system to be pinged.
    # Uncomment the LOG command if you also want to log PING attempts
    #
    # $IPT -A icmp_packets -p ICMP -s 0/0 --icmp-type 8 -j LOG \
    #    --log-prefix "Ping detected: "
    $IPT -A icmp_packets -p ICMP -s 0/0 --icmp-type 8 -j ACCEPT

    # By default, however, drop pings without logging. Blaster
    # and other worms have infected systems blasting pings.
    # Comment the line below if you want pings logged, but it
    # will likely fill your logs.
    $IPT -A icmp_packets -p ICMP -s 0/0 --icmp-type 8 -j DROP

    # Time Exceeded
    $IPT -A icmp_packets -p ICMP -s 0/0 --icmp-type 11 -j ACCEPT

    # Not matched, so return so it will be logged
    $IPT -A icmp_packets -p ICMP -j RETURN

    # TCP & UDP
    # Identify ports at:
    #    http://www.chebucto.ns.ca/~rakerman/port-table.html
    #    http://www.iana.org/assignments/port-numbers

    # udp_inbound chain
    #
    # This chain describes the inbound UDP packets it will accept.
    # It's applied to INPUT on the external or Internet interface.
    # Note that the stateful settings allow replies.
    # These rules are for new requests.
    # It drops netbios packets (windows) immediately without logging.

    # Drop netbios calls
    # Please note that these rules do not really change the way the firewall
    # treats netbios connections.  Connections from the localhost and
    # internal interface (if one exists) are accepted by default.
    # Responses from the Internet to requests initiated by or through
    # the firewall are also accepted by default.  To get here, the
    # packets would have to be part of a new request received by the
    # Internet interface.  You would have to manually add rules to
    # accept these.  I added these rules because some network connections,
    # such as those via cable modems, tend to be filled with noise from
    # unprotected Windows machines.  These rules drop those packets
    # quickly and without logging them.  This prevents them from traversing
    # the whole chain and keeps the log from getting cluttered with
    # chatter from Windows systems.
    $IPT -A udp_inbound -p UDP -s 0/0 --destination-port 137 -j DROP
    $IPT -A udp_inbound -p UDP -s 0/0 --destination-port 138 -j DROP

    # DNS Server
    # Configure the server to use port 53 as the source port for requests
    # Note, if you run a caching-only name server that only accepts queries
    # from the private network or localhost, you can comment out this line.
    $IPT -A udp_inbound -p UDP -s 0/0 --destination-port 53 -j ACCEPT

    # If you don't query-source the server to port 53 and you have problems,
    # uncomment this rule.  It specifically allows responses to queries
    # initiated to another server from a high UDP port.  The stateful
    # connection rules should handle this situation, though.
    # $IPT -A udp_inbound -p UDP -s 0/0 --source-port 53 -j ACCEPT

    # Dynamic Address
    # If DHCP, the initial request is a broadcast. The response
    # doesn't exactly match the outbound packet.  This explicitly
    # allow the DHCP ports to alleviate this problem.
    # If you receive your dynamic address by a different means, you
    # can probably comment this line.
    $IPT -A udp_inbound -p UDP -s 0/0 --source-port 67 --destination-port 68 \
    -j ACCEPT

    # User specified allowed UDP protocol
    $IPT -A udp_inbound -p UDP -s 0/0 --destination-port 3306 -j ACCEPT


    # Not matched, so return for logging
    $IPT -A udp_inbound -p UDP -j RETURN

    # udp_outbound chain
    #
    # This chain is used with a private network to prevent forwarding for
    # UDP requests on specific protocols.  Applied to the FORWARD rule from
    # the internal network.  Ends with an ACCEPT


    # No match, so ACCEPT
    $IPT -A udp_outbound -p UDP -s 0/0 -j ACCEPT

    # tcp_inbound chain
    #
    # This chain is used to allow inbound connections to the
    # system/gateway.  Use with care.  It defaults to none.
    # It's applied on INPUT from the external or Internet interface.

    # DNS Server - Allow TCP connections (zone transfers and large requests)
    # This is disabled by default.  DNS Zone transfers occur via TCP.
    # If you need to allow transfers over the net you need to uncomment this line.
    # If you allow queries from the 'net, you also need to be aware that although
    # DNS queries use UDP by default, a truncated UDP query can legally be
    # submitted via TCP instead.  You probably will never need it, but should
    # be aware of the fact.
    # $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 53 -j ACCEPT

    # Web Server

    # HTTP
    $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 80 -j ACCEPT

    # HTTPS (Secure Web Server)
    $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 443 -j ACCEPT

    # sshd
    $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 22 -j ACCEPT

    # vnc
    $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 5901 -j ACCEPT

    # User specified allowed UDP protocol
    $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 3306 -j ACCEPT


    # Not matched, so return so it will be logged
    $IPT -A tcp_inbound -p TCP -j RETURN

    # tcp_outbound chain
    #
    # This chain is used with a private network to prevent forwarding for
    # requests on specific protocols.  Applied to the FORWARD rule from
    # the internal network.  Ends with an ACCEPT


    # No match, so ACCEPT
    $IPT -A tcp_outbound -p TCP -s 0/0 -j ACCEPT

    ###############################################################################
    #
    # INPUT Chain
    #

    echo "Process INPUT chain ..."

    # Allow all on localhost interface
    $IPT -A INPUT -p ALL -i $LO_IFACE -j ACCEPT
    $IPT -A INPUT -p ALL -i $INET_IFACE1 -j ACCEPT
    $IPT -A INPUT -p ALL -i $INET_IFACE2 -j ACCEPT
    $IPT -A INPUT -p ALL -i $INET_IFACE3 -j ACCEPT
    $IPT -A INPUT -p ALL -i $INET_IFACE4 -j ACCEPT

    # Drop bad packets
    $IPT -A INPUT -p ALL -j bad_packets

    # DOCSIS compliant cable modems
    # Some DOCSIS compliant cable modems send IGMP multicasts to find
    # connected PCs.  The multicast packets have the destination address
    # 224.0.0.1.  You can accept them.  If you choose to do so,
    # Uncomment the rule to ACCEPT them and comment the rule to DROP
    # them  The firewall will drop them here by default to avoid
    # cluttering the log.  The firewall will drop all multicasts
    # to the entire subnet (224.0.0.1) by default.  To only affect
    # IGMP multicasts, change '-p ALL' to '-p 2'.  Of course,
    # if they aren't accepted elsewhere, it will only ensure that
    # multicasts on other protocols are logged.
    # Drop them without logging.
    $IPT -A INPUT -p ALL -d 224.0.0.1 -j DROP
    # The rule to accept the packets.
    # $IPT -A INPUT -p ALL -d 224.0.0.1 -j ACCEPT


    # Inbound Internet Packet Rules

    # Accept Established Connections
    $IPT -A INPUT -p ALL -i $INET_IFACE -m state --state ESTABLISHED,RELATED  -j ACCEPT

    # Route the rest to the appropriate user chain
    $IPT -A INPUT -p TCP -i $INET_IFACE -j tcp_inbound
    $IPT -A INPUT -p UDP -i $INET_IFACE -j udp_inbound
    $IPT -A INPUT -p ICMP -i $INET_IFACE -j icmp_packets

    # Drop without logging broadcasts that get this far.
    # Cuts down on log clutter.
    # Comment this line if testing new rules that impact
    # broadcast protocols.
    $IPT -A INPUT -m pkttype --pkt-type broadcast -j DROP

    ###############################################################################
    #
    # FORWARD Chain
    #

    echo "Process FORWARD chain ..."

    # Used if forwarding for a private network


    ###############################################################################
    #
    # OUTPUT Chain
    #

    echo "Process OUTPUT chain ..."

    # Generally trust the firewall on output

    # However, invalid icmp packets need to be dropped
    # to prevent a possible exploit.
    $IPT -A OUTPUT -m state -p icmp --state INVALID -j DROP

    # Localhost
    $IPT -A OUTPUT -p ALL -s $LO_IP -j ACCEPT
    $IPT -A OUTPUT -p ALL -o $LO_IFACE -j ACCEPT

    # To internet
    $IPT -A OUTPUT -p ALL -o $INET_IFACE -j ACCEPT
    $IPT -A OUTPUT -p ALL -o $INET_IFACE1 -j ACCEPT
    $IPT -A OUTPUT -p ALL -o $INET_IFACE2 -j ACCEPT
    $IPT -A OUTPUT -p ALL -o $INET_IFACE3 -j ACCEPT
    $IPT -A OUTPUT -p ALL -o $INET_IFACE4 -j ACCEPT

    ###############################################################################
    #
    # nat table
    #
    ###############################################################################

    # The nat table is where network address translation occurs if there
    # is a private network.  If the gateway is connected to the Internet
    # with a static IP, snat is used.  If the gateway has a dynamic address,
    # masquerade must be used instead.  There is more overhead associated
    # with masquerade, so snat is better when it can be used.
    # The nat table has a builtin chain, PREROUTING, for dnat and redirects.
    # Another, POSTROUTING, handles snat and masquerade.

    echo "Load rules for nat table ..."

    ###############################################################################
    #
    # PREROUTING chain
    #


    ###############################################################################
    #
    # POSTROUTING chain
    #


    ###############################################################################
    #
    # mangle table
    #
    ###############################################################################

    # The mangle table is used to alter packets.  It can alter or mangle them in
    # several ways.  For the purposes of this generator, we only use its ability
    # to alter the TTL in packets.  However, it can be used to set netfilter
    # mark values on specific packets.  Those marks could then be used in another
    # table like filter, to limit activities associated with a specific host, for
    # instance.  The TOS target can be used to set the Type of Service field in
    # the IP header.  Note that the TTL target might not be included in the
    # distribution on your system.  If it is not and you require it, you will
    # have to add it.  That may require that you build from source.

    echo "Load rules for mangle table ..."

    Cez bridge mi nechce prejst WAN.

    11.4.2010 02:13 rainbof | skóre: 16 | blog: Svet_podle_rainbofa
    Rozbalit Rozbalit vše Re: Firewall a bridge
    no nechapu. misto eth1 das br0 a eth1 das do bridge spolecne s ostatnima ktery tam mit chces. protoze jakmile das jednou eth do bridge tak pokud jsi se nezblaznil tak potom delas vse nad bridge.

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