Différences
Ci-dessous, les différences entre deux révisions de la page.
| Prochaine révision | Révision précédente | ||
| elearning:workbooks:centos:6:sec:l102 [2020/02/21 06:06] – créée admin | elearning:workbooks:centos:6:sec:l102 [2021/03/01 06:37] (Version actuelle) – admin | ||
|---|---|---|---|
| Ligne 1: | Ligne 1: | ||
| ~~PDF: | ~~PDF: | ||
| - | Version : **2020.01** | + | Version : **2021.01** |
| Dernière mise-à-jour : ~~LASTMOD~~ | Dernière mise-à-jour : ~~LASTMOD~~ | ||
| Ligne 7: | Ligne 7: | ||
| ======LRF402 - Netfilter et Firewalld====== | ======LRF402 - Netfilter et Firewalld====== | ||
| - | Dans cette unité, vous allez apprendre : | + | =====Contenu du Module===== |
| - | * Comment configurer | + | * **LRF402 - Netfilter |
| - | * Comment configurer | + | * Contenu du Module |
| + | * Les Problématiques | ||
| + | * L'IP Spoofing | ||
| + | * Déni de Service (DoS) | ||
| + | * SYN Flooding | ||
| + | * Flood | ||
| + | * Le Contre-Mesure | ||
| + | * Le Pare-feu | ||
| + | * LAB #1 - Configuration par Scripts sous RHEL/CentOS 6 et versions Antérieures | ||
| + | * LAB #2 - La Configuration par firewalld sous RHEL/CentOS 7 | ||
| + | * La Configuration de Base de firewalld | ||
| + | * La Commande firewall-cmd | ||
| + | * La Configuration Avancée de firewalld | ||
| + | * Le mode Panic de firewalld | ||
| =====Les Problématiques===== | =====Les Problématiques===== | ||
| Ligne 227: | Ligne 240: | ||
| iptables -A INPUT -j DROP | iptables -A INPUT -j DROP | ||
| </ | </ | ||
| - | |||
| - | Dans l' | ||
| - | |||
| - | < | ||
| - | #!/bin/sh | ||
| - | # | ||
| - | # Generated iptables firewall script for the Linux 2.4 kernel | ||
| - | # Script generated by Easy Firewall Generator for IPTables 1.15 | ||
| - | # copyright 2002 Timothy Scott Morizot | ||
| - | # | ||
| - | # Redhat chkconfig comments - firewall applied early, | ||
| - | # | ||
| - | # chkconfig: 2345 08 92 | ||
| - | # description: | ||
| - | # | ||
| - | # This generator is primarily designed for RedHat installations, | ||
| - | # although it should be adaptable for others. | ||
| - | # | ||
| - | # It can be executed with the typical start and stop arguments. | ||
| - | # If used with stop, it will stop after flushing the firewall. | ||
| - | # The save and restore arguments will save or restore the rules | ||
| - | # from the / | ||
| - | # arguments are included to preserve compatibility with | ||
| - | # Redhat' | ||
| - | |||
| - | # Redhat/ | ||
| - | # | ||
| - | # 1. Have the system link the iptables init.d startup script into run states | ||
| - | # 2, 3, and 5. | ||
| - | # chkconfig --level 235 iptables on | ||
| - | # | ||
| - | # 2. Save this script and execute it to load the ruleset from this file. | ||
| - | # You may need to run the dos2unix command on it to remove carraige returns. | ||
| - | # | ||
| - | # 3. To have it applied at startup, copy this script to | ||
| - | # / | ||
| - | # arguments. | ||
| - | # Alternatively, | ||
| - | # the init.d script should save the rules and reload them at runtime. | ||
| - | # | ||
| - | # 4. For non-Redhat systems (or Redhat systems if you have a problem), you | ||
| - | # may want to append the command to execute this script to rc.local. | ||
| - | # rc.local is typically located in /etc and /etc/rc.d and is usually | ||
| - | # the last thing executed on startup. | ||
| - | # on its own line in the rc.local file. | ||
| - | |||
| - | ############################################################################### | ||
| - | # | ||
| - | # Local Settings | ||
| - | # | ||
| - | |||
| - | # sysctl location. | ||
| - | # If this is set to the empty string (or is unset), the use of sysctl | ||
| - | # is disabled. | ||
| - | |||
| - | SYSCTL="/ | ||
| - | |||
| - | # To echo the value directly to the /proc file instead | ||
| - | # SYSCTL="" | ||
| - | |||
| - | # IPTables Location - adjust if needed | ||
| - | |||
| - | IPT="/ | ||
| - | IPTS="/ | ||
| - | IPTR="/ | ||
| - | |||
| - | # Internet Interface | ||
| - | INET_IFACE=" | ||
| - | |||
| - | # Local Interface Information | ||
| - | LOCAL_IFACE=" | ||
| - | LOCAL_IP=" | ||
| - | LOCAL_NET=" | ||
| - | LOCAL_BCAST=" | ||
| - | |||
| - | # Localhost Interface | ||
| - | |||
| - | LO_IFACE=" | ||
| - | LO_IP=" | ||
| - | |||
| - | # Save and Restore arguments handled here | ||
| - | if [ " | ||
| - | then | ||
| - | echo -n " | ||
| - | $IPTS > / | ||
| - | echo " | ||
| - | exit 0 | ||
| - | elif [ " | ||
| - | then | ||
| - | echo -n " | ||
| - | $IPTR < / | ||
| - | echo " | ||
| - | exit 0 | ||
| - | fi | ||
| - | |||
| - | ############################################################################### | ||
| - | # | ||
| - | # Load Modules | ||
| - | # | ||
| - | |||
| - | echo " | ||
| - | |||
| - | # You should uncomment the line below and run it the first time just to | ||
| - | # ensure all kernel module dependencies are OK. There is no need to run | ||
| - | # every time, however. | ||
| - | |||
| - | # / | ||
| - | |||
| - | # Unless you have kernel module auto-loading disabled, you should not | ||
| - | # need to manually load each of these modules. | ||
| - | # ip_conntrack, | ||
| - | # commented by default. | ||
| - | # you have disabled module autoload. | ||
| - | # be loaded by another kernel module. | ||
| - | |||
| - | # core netfilter module | ||
| - | / | ||
| - | |||
| - | # the stateful connection tracking module | ||
| - | / | ||
| - | |||
| - | # filter table module | ||
| - | # / | ||
| - | |||
| - | # mangle table module | ||
| - | # / | ||
| - | |||
| - | # nat table module | ||
| - | # / | ||
| - | |||
| - | # LOG target module | ||
| - | # / | ||
| - | |||
| - | # This is used to limit the number of packets per sec/min/hr | ||
| - | # / | ||
| - | |||
| - | # masquerade target module | ||
| - | # / | ||
| - | |||
| - | # filter using owner as part of the match | ||
| - | # / | ||
| - | |||
| - | # REJECT target drops the packet and returns an ICMP response. | ||
| - | # The response is configurable. | ||
| - | # / | ||
| - | |||
| - | # This target allows packets to be marked in the mangle table | ||
| - | # / | ||
| - | |||
| - | # This target affects the TCP MSS | ||
| - | # / | ||
| - | |||
| - | # This match allows multiple ports instead of a single port or range | ||
| - | # / | ||
| - | |||
| - | # This match checks against the TCP flags | ||
| - | # / | ||
| - | |||
| - | # This match catches packets with invalid flags | ||
| - | # / | ||
| - | |||
| - | # The ftp nat module is required for non-PASV ftp support | ||
| - | / | ||
| - | |||
| - | # the module for full ftp connection tracking | ||
| - | / | ||
| - | |||
| - | # the module for full irc connection tracking | ||
| - | / | ||
| - | |||
| - | |||
| - | ############################################################################### | ||
| - | # | ||
| - | # Kernel Parameter Configuration | ||
| - | # | ||
| - | # See http:// | ||
| - | # for a detailed tutorial on sysctl and the various settings | ||
| - | # available. | ||
| - | |||
| - | # Required to enable IPv4 forwarding. | ||
| - | # Redhat users can try setting FORWARD_IPV4 in / | ||
| - | # Alternatively, | ||
| - | if [ " | ||
| - | then | ||
| - | echo " | ||
| - | else | ||
| - | $SYSCTL net.ipv4.ip_forward=" | ||
| - | fi | ||
| - | |||
| - | # This enables dynamic address hacking. | ||
| - | # This may help if you have a dynamic IP address \(e.g. slip, ppp, dhcp\). | ||
| - | #if [ " | ||
| - | #then | ||
| - | # echo " | ||
| - | #else | ||
| - | # $SYSCTL net.ipv4.ip_dynaddr=" | ||
| - | #fi | ||
| - | |||
| - | # This enables SYN flood protection. | ||
| - | # The SYN cookies activation allows your system to accept an unlimited | ||
| - | # number of TCP connections while still trying to give reasonable | ||
| - | # service during a denial of service attack. | ||
| - | if [ " | ||
| - | then | ||
| - | echo " | ||
| - | else | ||
| - | $SYSCTL net.ipv4.tcp_syncookies=" | ||
| - | fi | ||
| - | |||
| - | # This enables source validation by reversed path according to RFC1812. | ||
| - | # In other words, did the response packet originate from the same interface | ||
| - | # through which the source packet was sent? It's recommended for single-homed | ||
| - | # systems and routers on stub networks. | ||
| - | # this firewall is designed to support, I turn it on by default. | ||
| - | # Turn it off if you use multiple NICs connected to the same network. | ||
| - | if [ " | ||
| - | then | ||
| - | echo " | ||
| - | else | ||
| - | $SYSCTL net.ipv4.conf.all.rp_filter=" | ||
| - | fi | ||
| - | |||
| - | # This option allows a subnet to be firewalled with a single IP address. | ||
| - | # It's used to build a DMZ. Since that's not a focus of this firewall | ||
| - | # script, it's not enabled by default, but is included for reference. | ||
| - | # See: http:// | ||
| - | #if [ " | ||
| - | #then | ||
| - | # echo " | ||
| - | #else | ||
| - | # $SYSCTL net.ipv4.conf.all.proxy_arp=" | ||
| - | #fi | ||
| - | |||
| - | # The following kernel settings were suggested by Alex Weeks. Thanks! | ||
| - | |||
| - | # This kernel parameter instructs the kernel to ignore all ICMP | ||
| - | # echo requests sent to the broadcast address. | ||
| - | # a number of smurfs and similar DoS nasty attacks. | ||
| - | if [ " | ||
| - | then | ||
| - | echo " | ||
| - | else | ||
| - | $SYSCTL net.ipv4.icmp_echo_ignore_broadcasts=" | ||
| - | fi | ||
| - | |||
| - | # This option can be used to accept or refuse source routed | ||
| - | # packets. | ||
| - | # considered a security risk. This option turns it off. | ||
| - | if [ " | ||
| - | then | ||
| - | echo " | ||
| - | else | ||
| - | $SYSCTL net.ipv4.conf.all.accept_source_route=" | ||
| - | fi | ||
| - | |||
| - | # This option can disable ICMP redirects. | ||
| - | # are generally considered a security risk and shouldn' | ||
| - | # needed by most systems using this generator. | ||
| - | #if [ " | ||
| - | #then | ||
| - | # echo " | ||
| - | #else | ||
| - | # $SYSCTL net.ipv4.conf.all.accept_redirects=" | ||
| - | #fi | ||
| - | |||
| - | # However, we'll ensure the secure_redirects option is on instead. | ||
| - | # This option accepts only from gateways in the default gateways list. | ||
| - | if [ " | ||
| - | then | ||
| - | echo " | ||
| - | else | ||
| - | $SYSCTL net.ipv4.conf.all.secure_redirects=" | ||
| - | fi | ||
| - | |||
| - | # This option logs packets from impossible addresses. | ||
| - | if [ " | ||
| - | then | ||
| - | echo " | ||
| - | else | ||
| - | $SYSCTL net.ipv4.conf.all.log_martians=" | ||
| - | fi | ||
| - | |||
| - | |||
| - | ############################################################################### | ||
| - | # | ||
| - | # Flush Any Existing Rules or Chains | ||
| - | # | ||
| - | |||
| - | echo " | ||
| - | |||
| - | # 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 [ " | ||
| - | then | ||
| - | echo " | ||
| - | 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 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 | ||
| - | # | ||
| - | |||
| - | # Drop packets received on the external interface | ||
| - | # claiming a source of the local network | ||
| - | $IPT -A bad_packets -p ALL -i $INET_IFACE -s $LOCAL_NET -j LOG \ | ||
| - | --log-prefix " | ||
| - | $IPT -A bad_packets -p ALL -i $INET_IFACE -s $LOCAL_NET -j DROP | ||
| - | |||
| - | # Drop INVALID packets immediately | ||
| - | $IPT -A bad_packets -p ALL -m state --state INVALID -j LOG \ | ||
| - | --log-prefix " | ||
| - | |||
| - | $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. | ||
| - | # port scan. This drops packets in state | ||
| - | # NEW that are not flagged as syn packets. | ||
| - | |||
| - | # Return to the calling chain if the bad packets originate | ||
| - | # from the local interface. This maintains the approach | ||
| - | # throughout this firewall of a largely trusted internal | ||
| - | # network. | ||
| - | $IPT -A bad_tcp_packets -p tcp -i $LOCAL_IFACE -j RETURN | ||
| - | |||
| - | # However, I originally did apply this filter to the forward chain | ||
| - | # for packets originating from the internal network. | ||
| - | # not conclusively determined its effect, it appears to have the | ||
| - | # interesting side effect of blocking some of the ad systems. | ||
| - | # Apparently some ad systems have the browser initiate a NEW | ||
| - | # connection that is not flagged as a syn packet to retrieve | ||
| - | # the ad image. | ||
| - | # rule above. If you try it, you may also wish to uncomment the | ||
| - | # rule below. | ||
| - | # There are a lot of them. | ||
| - | # $IPT -A bad_tcp_packets -p tcp -i $LOCAL_IFACE ! --syn -m state \ | ||
| - | # | ||
| - | |||
| - | $IPT -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j LOG \ | ||
| - | --log-prefix " | ||
| - | $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 LOG \ | ||
| - | --log-prefix " | ||
| - | $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 LOG \ | ||
| - | --log-prefix " | ||
| - | $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 LOG \ | ||
| - | --log-prefix " | ||
| - | $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, | ||
| - | --log-prefix " | ||
| - | $IPT -A bad_tcp_packets -p tcp --tcp-flags ALL SYN, | ||
| - | |||
| - | $IPT -A bad_tcp_packets -p tcp --tcp-flags SYN,RST SYN,RST -j LOG \ | ||
| - | --log-prefix " | ||
| - | $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 LOG \ | ||
| - | --log-prefix " | ||
| - | $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:// | ||
| - | # 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. | ||
| - | # of a denial of service attack. | ||
| - | $IPT -A icmp_packets --fragment -p ICMP -j LOG \ | ||
| - | --log-prefix " | ||
| - | $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 " | ||
| - | # $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:// | ||
| - | # http:// | ||
| - | |||
| - | # 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. | ||
| - | # 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. | ||
| - | # packets would have to be part of a new request received by the | ||
| - | # Internet interface. | ||
| - | # accept these. | ||
| - | # such as those via cable modems, tend to be filled with noise from | ||
| - | # unprotected Windows machines. | ||
| - | # 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 | ||
| - | |||
| - | # Ident requests (Port 113) must have a REJECT rule rather than the | ||
| - | # default DROP rule. This is the minimum requirement to avoid | ||
| - | # long delays while connecting. | ||
| - | $IPT -A udp_inbound -p UDP -s 0/0 --destination-port 113 -j REJECT | ||
| - | |||
| - | # A more sophisticated configuration could accept the ident requests. | ||
| - | # $IPT -A udp_inbound -p UDP -s 0/0 --destination-port 113 -j ACCEPT | ||
| - | |||
| - | # However, if this is a gateway system that masquerades/ | ||
| - | # and the internal systems wish to chat, a simple changing these rules to | ||
| - | # ACCEPT won't work. The ident daemon on the gateway will need to know how | ||
| - | # to handle the requests. | ||
| - | # can't do that. | ||
| - | # See: http:// | ||
| - | |||
| - | # Network Time Protocol (NTP) Server | ||
| - | $IPT -A udp_inbound -p UDP -s 0/0 --destination-port 123 -j ACCEPT | ||
| - | |||
| - | # Dynamic Address | ||
| - | # If DHCP, the initial request is a broadcast. The response | ||
| - | # doesn' | ||
| - | # 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 | ||
| - | |||
| - | |||
| - | # 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. | ||
| - | # the internal network. | ||
| - | |||
| - | |||
| - | # 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/ | ||
| - | # It's applied on INPUT from the external or Internet interface. | ||
| - | |||
| - | # Ident requests (Port 113) must have a REJECT rule rather than the | ||
| - | # default DROP rule. This is the minimum requirement to avoid | ||
| - | # long delays while connecting. | ||
| - | $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 113 -j REJECT | ||
| - | |||
| - | # A more sophisticated configuration could accept the ident requests. | ||
| - | # $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 113 -j ACCEPT | ||
| - | |||
| - | # However, if this is a gateway system that masquerades/ | ||
| - | # and the internal systems wish to chat, a simple changing these rules to | ||
| - | # ACCEPT won't work. The ident daemon on the gateway will need to know how | ||
| - | # to handle the requests. | ||
| - | # can't do that. | ||
| - | # See: http:// | ||
| - | |||
| - | # 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 | ||
| - | |||
| - | # FTP Server (Control) | ||
| - | $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 21 -j ACCEPT | ||
| - | |||
| - | # FTP Client (Data Port for non-PASV transfers) | ||
| - | $IPT -A tcp_inbound -p TCP -s 0/0 --source-port 20 -j ACCEPT | ||
| - | |||
| - | # Passive FTP | ||
| - | # | ||
| - | # With passive FTP, the server provides a port to the client | ||
| - | # and allows the client to initiate the connection rather | ||
| - | # than initiating the connection with the client from the data port. | ||
| - | # Web browsers and clients operating behind a firewall generally | ||
| - | # use passive ftp transfers. | ||
| - | # will need to support them. | ||
| - | # | ||
| - | # However, by default an FTP server will select a port from the entire | ||
| - | # range of high ports. | ||
| - | # high ports. | ||
| - | # firewall presumes that the range has been restricted to a specific | ||
| - | # selected range. | ||
| - | # | ||
| - | # Instructions for specifying the port range for the wu-ftpd server | ||
| - | # can be found here: | ||
| - | # http:// | ||
| - | # (See the passive ports option.) | ||
| - | # | ||
| - | # Instructions for the ProFTPD server can be found here: | ||
| - | # http:// | ||
| - | |||
| - | $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 62000:64000 -j ACCEPT | ||
| - | |||
| - | # Email Server (SMTP) | ||
| - | $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 25 -j ACCEPT | ||
| - | |||
| - | # Email Server (POP3) | ||
| - | $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 110 -j ACCEPT | ||
| - | |||
| - | # Email Server (IMAP4) | ||
| - | $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 143 -j ACCEPT | ||
| - | |||
| - | # SSL Email Server (POP3) | ||
| - | $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 995 -j ACCEPT | ||
| - | |||
| - | # SSL Email Server (IMAP4) | ||
| - | $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 993 -j ACCEPT | ||
| - | |||
| - | # sshd | ||
| - | $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 22 -j ACCEPT | ||
| - | |||
| - | # ICQ File Transfers & Other Advanced Features | ||
| - | # | ||
| - | # ICQ supports a number of options beyond simple instant messaging. | ||
| - | # For those to function, the instant messaging system must allow | ||
| - | # new connections initiated from remote systems. This option will | ||
| - | # open a specified port range on the firewalled system. | ||
| - | # on the firewalled system must also be configured to use the specified | ||
| - | # port range. | ||
| - | |||
| - | $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 5000:5100 -j ACCEPT | ||
| - | |||
| - | # MSN Messenger File Transfers | ||
| - | # | ||
| - | # Messenger supports file transfers. | ||
| - | # remote systems to function, the system must allow | ||
| - | # new connections initiated from remote systems a specific port range. | ||
| - | # This option defaults to the port range 6891 through 6900. | ||
| - | # Unless the MSN Messenger client can be configured to specify any | ||
| - | # port range, don't change the default. | ||
| - | |||
| - | $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 6891:6900 -j ACCEPT | ||
| - | |||
| - | # User specified allowed UDP protocol | ||
| - | $IPT -A tcp_inbound -p TCP -s 0/0 --destination-port 32500:36000 -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. | ||
| - | # the internal network. | ||
| - | |||
| - | |||
| - | # No match, so ACCEPT | ||
| - | $IPT -A tcp_outbound -p TCP -s 0/0 -j ACCEPT | ||
| - | |||
| - | ############################################################################### | ||
| - | # | ||
| - | # INPUT Chain | ||
| - | # | ||
| - | |||
| - | echo " | ||
| - | |||
| - | # Allow all on localhost interface | ||
| - | $IPT -A INPUT -p ALL -i $LO_IFACE -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. | ||
| - | # 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. | ||
| - | # IGMP multicasts, change '-p ALL' to '-p 2' | ||
| - | # 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 | ||
| - | |||
| - | # Rules for the private network (accessing gateway system itself) | ||
| - | $IPT -A INPUT -p ALL -i $LOCAL_IFACE -s $LOCAL_NET -j ACCEPT | ||
| - | $IPT -A INPUT -p ALL -i $LOCAL_IFACE -d $LOCAL_BCAST -j ACCEPT | ||
| - | |||
| - | |||
| - | # Inbound Internet Packet Rules | ||
| - | |||
| - | # Accept Established Connections | ||
| - | $IPT -A INPUT -p ALL -i $INET_IFACE -m state --state ESTABLISHED, | ||
| - | -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 | ||
| - | |||
| - | # Log packets that still don't match | ||
| - | $IPT -A INPUT -j LOG --log-prefix " | ||
| - | |||
| - | ############################################################################### | ||
| - | # | ||
| - | # FORWARD Chain | ||
| - | # | ||
| - | |||
| - | echo " | ||
| - | |||
| - | # Used if forwarding for a private network | ||
| - | |||
| - | # Drop bad packets | ||
| - | $IPT -A FORWARD -p ALL -j bad_packets | ||
| - | |||
| - | # Accept TCP packets we want to forward from internal sources | ||
| - | $IPT -A FORWARD -p tcp -i $LOCAL_IFACE -j tcp_outbound | ||
| - | |||
| - | # Accept UDP packets we want to forward from internal sources | ||
| - | $IPT -A FORWARD -p udp -i $LOCAL_IFACE -j udp_outbound | ||
| - | |||
| - | # If not blocked, accept any other packets from the internal interface | ||
| - | $IPT -A FORWARD -p ALL -i $LOCAL_IFACE -j ACCEPT | ||
| - | |||
| - | # Deal with responses from the internet | ||
| - | $IPT -A FORWARD -i $INET_IFACE -m state --state ESTABLISHED, | ||
| - | -j ACCEPT | ||
| - | |||
| - | # Port Forwarding is enabled, so accept forwarded traffic | ||
| - | $IPT -A FORWARD -p tcp -i $INET_IFACE --destination-port 8080 \ | ||
| - | | ||
| - | |||
| - | # Log packets that still don't match | ||
| - | $IPT -A FORWARD -j LOG --log-prefix " | ||
| - | |||
| - | ############################################################################### | ||
| - | # | ||
| - | # OUTPUT Chain | ||
| - | # | ||
| - | |||
| - | echo " | ||
| - | |||
| - | # 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 internal network | ||
| - | $IPT -A OUTPUT -p ALL -s $LOCAL_IP -j ACCEPT | ||
| - | $IPT -A OUTPUT -p ALL -o $LOCAL_IFACE -j ACCEPT | ||
| - | |||
| - | # To internet | ||
| - | $IPT -A OUTPUT -p ALL -o $INET_IFACE -j ACCEPT | ||
| - | |||
| - | # Log packets that still don't match | ||
| - | $IPT -A OUTPUT -j LOG --log-prefix " | ||
| - | |||
| - | ############################################################################### | ||
| - | # | ||
| - | # nat table | ||
| - | # | ||
| - | ############################################################################### | ||
| - | |||
| - | # The nat table is where network address translation occurs if there | ||
| - | # is a private network. | ||
| - | # with a static IP, snat is used. If the gateway has a dynamic address, | ||
| - | # masquerade must be used instead. | ||
| - | # 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, | ||
| - | |||
| - | echo "Load rules for nat table ..." | ||
| - | |||
| - | ############################################################################### | ||
| - | # | ||
| - | # PREROUTING chain | ||
| - | # | ||
| - | |||
| - | # Port Forwarding | ||
| - | # | ||
| - | # Port forwarding forwards all traffic on a port or ports from | ||
| - | # the firewall to a computer on the internal LAN. This can | ||
| - | # be required to support special situations. | ||
| - | # this is the only way to support file transfers with an ICQ | ||
| - | # client on an internal computer. | ||
| - | # system hosts a service such as a web server. | ||
| - | # a dangerous option. | ||
| - | # your internal network. | ||
| - | # certain you know what you're doing. | ||
| - | |||
| - | $IPT -t nat -A PREROUTING -p tcp -i $INET_IFACE --destination-port 80:80 \ | ||
| - | -j DNAT --to-destination 192.168.1.50: | ||
| - | |||
| - | # This is a sample that will exempt a specific host from the transparent proxy | ||
| - | #$IPT -t nat -A PREROUTING -p tcp -s 192.168.1.50 --destination-port 80 \ | ||
| - | # -j RETURN | ||
| - | #$IPT -t nat -A PREROUTING -p tcp -s 192.168.1.50 --destination-port 443 \ | ||
| - | # -j RETURN | ||
| - | |||
| - | # Redirect HTTP for a transparent proxy | ||
| - | $IPT -t nat -A PREROUTING -p tcp --destination-port 80 \ | ||
| - | -j REDIRECT --to-ports 3128 | ||
| - | # Redirect HTTPS for a transparent proxy - commented by default | ||
| - | # $IPT -t nat -A PREROUTING -p tcp --destination-port 443 \ | ||
| - | # -j REDIRECT --to-ports 3128 | ||
| - | |||
| - | ############################################################################### | ||
| - | # | ||
| - | # POSTROUTING chain | ||
| - | # | ||
| - | |||
| - | $IPT -t nat -A POSTROUTING -o $INET_IFACE -j MASQUERADE | ||
| - | |||
| - | ############################################################################### | ||
| - | # | ||
| - | # mangle table | ||
| - | # | ||
| - | ############################################################################### | ||
| - | |||
| - | # The mangle table is used to alter packets. | ||
| - | # several ways. For the purposes of this generator, we only use its ability | ||
| - | # to alter the TTL in packets. | ||
| - | # mark values on specific packets. | ||
| - | # table like filter, to limit activities associated with a specific host, for | ||
| - | # instance. | ||
| - | # the IP header. | ||
| - | # distribution on your system. | ||
| - | # have to add it. That may require that you build from source. | ||
| - | |||
| - | echo "Load rules for mangle table ..." | ||
| - | |||
| - | # Set the TTL in outbound packets to the same consistent value. | ||
| - | # A value around 128 is a good value. | ||
| - | # it will adversely affect your network. | ||
| - | # form on the Internet. | ||
| - | $IPT -t mangle -A OUTPUT -o $INET_IFACE -j TTL --ttl-set 128 | ||
| - | </ | ||
| - | |||
| - | <WRAP center round todo 50%> | ||
| - | **A Faire** - Utilisez la commande **system-config-firewall** pour lancer l' | ||
| - | </ | ||
| ====LAB #2 - La Configuration par firewalld sous RHEL/CentOS 7==== | ====LAB #2 - La Configuration par firewalld sous RHEL/CentOS 7==== | ||
| Ligne 1736: | Ligne 869: | ||
| < | < | ||
| <div align=" | <div align=" | ||
| - | Copyright © 2020 Hugh Norris.< | + | Copyright © 2021 Hugh Norris.< |
| </ | </ | ||
| </ | </ | ||
