# # IP netfilter configuration # menu "IP: Netfilter Configuration" depends on INET && NETFILTER # connection tracking, helpers and protocols config IP_NF_CONNTRACK tristate "Connection tracking (required for masq/NAT)" ---help--- Connection tracking keeps a record of what packets have passed through your machine, in order to figure out how they are related into connections. This is required to do Masquerading or other kinds of Network Address Translation (except for Fast NAT). It can also be used to enhance packet filtering (see `Connection state match support' below). To compile it as a module, choose M here. If unsure, say N. config IP_NF_CT_ACCT bool "Connection tracking flow accounting" depends on IP_NF_CONNTRACK help If this option is enabled, the connection tracking code will keep per-flow packet and byte counters. Those counters can be used for flow-based accounting or the `connbytes' match. If unsure, say `N'. config IP_NF_CONNTRACK_MARK bool 'Connection mark tracking support' depends on IP_NF_CONNTRACK help This option enables support for connection marks, used by the `CONNMARK' target and `connmark' match. Similar to the mark value of packets, but this mark value is kept in the conntrack session instead of the individual packets. config IP_NF_CONNTRACK_EVENTS bool "Connection tracking events" depends on IP_NF_CONNTRACK help If this option is enabled, the connection tracking code will provide a notifier chain that can be used by other kernel code to get notified about changes in the connection tracking state. IF unsure, say `N'. config IP_NF_CT_PROTO_SCTP tristate 'SCTP protocol connection tracking support (EXPERIMENTAL)' depends on IP_NF_CONNTRACK && EXPERIMENTAL help With this option enabled, the connection tracking code will be able to do state tracking on SCTP connections. If you want to compile it as a module, say M here and read . If unsure, say `N'. config IP_NF_FTP tristate "FTP protocol support" depends on IP_NF_CONNTRACK help Tracking FTP connections is problematic: special helpers are required for tracking them, and doing masquerading and other forms of Network Address Translation on them. To compile it as a module, choose M here. If unsure, say Y. config IP_NF_IRC tristate "IRC protocol support" depends on IP_NF_CONNTRACK ---help--- There is a commonly-used extension to IRC called Direct Client-to-Client Protocol (DCC). This enables users to send files to each other, and also chat to each other without the need of a server. DCC Sending is used anywhere you send files over IRC, and DCC Chat is most commonly used by Eggdrop bots. If you are using NAT, this extension will enable you to send files and initiate chats. Note that you do NOT need this extension to get files or have others initiate chats, or everything else in IRC. To compile it as a module, choose M here. If unsure, say Y. config IP_NF_NETBIOS_NS tristate "NetBIOS name service protocol support (EXPERIMENTAL)" depends on IP_NF_CONNTRACK && EXPERIMENTAL help NetBIOS name service requests are sent as broadcast messages from an unprivileged port and responded to with unicast messages to the same port. This make them hard to firewall properly because connection tracking doesn't deal with broadcasts. This helper tracks locally originating NetBIOS name service requests and the corresponding responses. It relies on correct IP address configuration, specifically netmask and broadcast address. When properly configured, the output of "ip address show" should look similar to this: $ ip -4 address show eth0 4: eth0: mtu 1500 qdisc pfifo_fast qlen 1000 inet 172.16.2.252/24 brd 172.16.2.255 scope global eth0 To compile it as a module, choose M here. If unsure, say N. config IP_NF_TFTP tristate "TFTP protocol support" depends on IP_NF_CONNTRACK help TFTP connection tracking helper, this is required depending on how restrictive your ruleset is. If you are using a tftp client behind -j SNAT or -j MASQUERADING you will need this. To compile it as a module, choose M here. If unsure, say Y. config IP_NF_AMANDA tristate "Amanda backup protocol support" depends on IP_NF_CONNTRACK help If you are running the Amanda backup package on this machine or machines that will be MASQUERADED through this machine, then you may want to enable this feature. This allows the connection tracking and natting code to allow the sub-channels that Amanda requires for communication of the backup data, messages and index. To compile it as a module, choose M here. If unsure, say Y. config IP_NF_QUEUE tristate "IP Userspace queueing via NETLINK (OBSOLETE)" help Netfilter has the ability to queue packets to user space: the netlink device can be used to access them using this driver. This option enables the old IPv4-only "ip_queue" implementation which has been obsoleted by the new "nfnetlink_queue" code (see CONFIG_NETFILTER_NETLINK_QUEUE). To compile it as a module, choose M here. If unsure, say N. config IP_NF_IPTABLES tristate "IP tables support (required for filtering/masq/NAT)" help iptables is a general, extensible packet identification framework. The packet filtering and full NAT (masquerading, port forwarding, etc) subsystems now use this: say `Y' or `M' here if you want to use either of those. To compile it as a module, choose M here. If unsure, say N. # The matches. config IP_NF_MATCH_LIMIT tristate "limit match support" depends on IP_NF_IPTABLES help limit matching allows you to control the rate at which a rule can be matched: mainly useful in combination with the LOG target ("LOG target support", below) and to avoid some Denial of Service attacks. To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_IPRANGE tristate "IP range match support" depends on IP_NF_IPTABLES help This option makes possible to match IP addresses against IP address ranges. To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_MAC tristate "MAC address match support" depends on IP_NF_IPTABLES help MAC matching allows you to match packets based on the source Ethernet address of the packet. To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_PKTTYPE tristate "Packet type match support" depends on IP_NF_IPTABLES help Packet type matching allows you to match a packet by its "class", eg. BROADCAST, MULTICAST, ... Typical usage: iptables -A INPUT -m pkttype --pkt-type broadcast -j LOG To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_MARK tristate "netfilter MARK match support" depends on IP_NF_IPTABLES help Netfilter mark matching allows you to match packets based on the `nfmark' value in the packet. This can be set by the MARK target (see below). To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_MULTIPORT tristate "Multiple port match support" depends on IP_NF_IPTABLES help Multiport matching allows you to match TCP or UDP packets based on a series of source or destination ports: normally a rule can only match a single range of ports. To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_TOS tristate "TOS match support" depends on IP_NF_IPTABLES help TOS matching allows you to match packets based on the Type Of Service fields of the IP packet. To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_RECENT tristate "recent match support" depends on IP_NF_IPTABLES help This match is used for creating one or many lists of recently used addresses and then matching against that/those list(s). Short options are available by using 'iptables -m recent -h' Official Website: To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_ECN tristate "ECN match support" depends on IP_NF_IPTABLES help This option adds a `ECN' match, which allows you to match against the IPv4 and TCP header ECN fields. To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_DSCP tristate "DSCP match support" depends on IP_NF_IPTABLES help This option adds a `DSCP' match, which allows you to match against the IPv4 header DSCP field (DSCP codepoint). The DSCP codepoint can have any value between 0x0 and 0x4f. To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_AH_ESP tristate "AH/ESP match support" depends on IP_NF_IPTABLES help These two match extensions (`ah' and `esp') allow you to match a range of SPIs inside AH or ESP headers of IPSec packets. To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_LENGTH tristate "LENGTH match support" depends on IP_NF_IPTABLES help This option allows you to match the length of a packet against a specific value or range of values. To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_TTL tristate "TTL match support" depends on IP_NF_IPTABLES help This adds CONFIG_IP_NF_MATCH_TTL option, which enabled the user to match packets by their TTL value. To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_TCPMSS tristate "tcpmss match support" depends on IP_NF_IPTABLES help This option adds a `tcpmss' match, which allows you to examine the MSS value of TCP SYN packets, which control the maximum packet size for that connection. To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_HELPER tristate "Helper match support" depends on IP_NF_CONNTRACK && IP_NF_IPTABLES help Helper matching allows you to match packets in dynamic connections tracked by a conntrack-helper, ie. ip_conntrack_ftp To compile it as a module, choose M here. If unsure, say Y. config IP_NF_MATCH_STATE tristate "Connection state match support" depends on IP_NF_CONNTRACK && IP_NF_IPTABLES help Connection state matching allows you to match packets based on their relationship to a tracked connection (ie. previous packets). This is a powerful tool for packet classification. To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_CONNTRACK tristate "Connection tracking match support" depends on IP_NF_CONNTRACK && IP_NF_IPTABLES help This is a general conntrack match module, a superset of the state match. It allows matching on additional conntrack information, which is useful in complex configurations, such as NAT gateways with multiple internet links or tunnels. To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_OWNER tristate "Owner match support" depends on IP_NF_IPTABLES help Packet owner matching allows you to match locally-generated packets based on who created them: the user, group, process or session. To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_PHYSDEV tristate "Physdev match support" depends on IP_NF_IPTABLES && BRIDGE_NETFILTER help Physdev packet matching matches against the physical bridge ports the IP packet arrived on or will leave by. To compile it as a module, choose M here. If unsure, say N. config IP_NF_MATCH_ADDRTYPE tristate 'address type match support' depends on IP_NF_IPTABLES help This option allows you to match what routing thinks of an address, eg. UNICAST, LOCAL, BROADCAST, ... If you want to compile it as a module, say M here and read . If unsure, say `N'. config IP_NF_MATCH_REALM tristate 'realm match support' depends on IP_NF_IPTABLES select NET_CLS_ROUTE help This option adds a `realm' match, which allows you to use the realm key from the routing subsystem inside iptables. This match pretty much resembles the CONFIG_NET_CLS_ROUTE4 option in tc world. If you want to compile it as a module, say M here and read . If unsure, say `N'. config IP_NF_MATCH_SCTP tristate 'SCTP protocol match support' depends on IP_NF_IPTABLES help With this option enabled, you will be able to use the iptables `sctp' match in order to match on SCTP source/destination ports and SCTP chunk types. If you want to compile it as a module, say M here and read . If unsure, say `N'. config IP_NF_MATCH_DCCP tristate 'DCCP protocol match support' depends on IP_NF_IPTABLES help With this option enabled, you will be able to use the iptables `dccp' match in order to match on DCCP source/destination ports and DCCP flags. If you want to compile it as a module, say M here and read . If unsure, say `N'. config IP_NF_MATCH_COMMENT tristate 'comment match support' depends on IP_NF_IPTABLES help This option adds a `comment' dummy-match, which allows you to put comments in your iptables ruleset. If you want to compile it as a module, say M here and read . If unsure, say `N'. config IP_NF_MATCH_CONNMARK tristate 'Connection mark match support' depends on IP_NF_CONNTRACK_MARK && IP_NF_IPTABLES help This option adds a `connmark' match, which allows you to match the connection mark value previously set for the session by `CONNMARK'. If you want to compile it as a module, say M here and read . The module will be called ipt_connmark.o. If unsure, say `N'. config IP_NF_MATCH_CONNBYTES tristate 'Connection byte/packet counter match support' depends on IP_NF_CT_ACCT && IP_NF_IPTABLES help This option adds a `connbytes' match, which allows you to match the number of bytes and/or packets for each direction within a connection. If you want to compile it as a module, say M here and read . If unsure, say `N'. config IP_NF_MATCH_HASHLIMIT tristate 'hashlimit match support' depends on IP_NF_IPTABLES help This option adds a new iptables `hashlimit' match. As opposed to `limit', this match dynamically crates a hash table of limit buckets, based on your selection of source/destination ip addresses and/or ports. It enables you to express policies like `10kpps for any given destination IP' or `500pps from any given source IP' with a single IPtables rule. config IP_NF_MATCH_STRING tristate 'string match support' depends on IP_NF_IPTABLES select TEXTSEARCH select TEXTSEARCH_KMP select TEXTSEARCH_BM select TEXTSEARCH_FSM help This option adds a `string' match, which allows you to look for pattern matchings in packets. To compile it as a module, choose M here. If unsure, say N. # `filter', generic and specific targets config IP_NF_FILTER tristate "Packet filtering" depends on IP_NF_IPTABLES help Packet filtering defines a table `filter', which has a series of rules for simple packet filtering at local input, forwarding and local output. See the man page for iptables(8). To compile it as a module, choose M here. If unsure, say N. config IP_NF_TARGET_REJECT tristate "REJECT target support" depends on IP_NF_FILTER help The REJECT target allows a filtering rule to specify that an ICMP error should be issued in response to an incoming packet, rather than silently being dropped. To compile it as a module, choose M here. If unsure, say N. config IP_NF_TARGET_LOG tristate "LOG target support" depends on IP_NF_IPTABLES help This option adds a `LOG' target, which allows you to create rules in any iptables table which records the packet header to the syslog. To compile it as a module, choose M here. If unsure, say N. config IP_NF_TARGET_ULOG tristate "ULOG target support" depends on IP_NF_IPTABLES ---help--- This option adds a `ULOG' target, which allows you to create rules in any iptables table. The packet is passed to a userspace logging daemon using netlink multicast sockets; unlike the LOG target which can only be viewed through syslog. The apropriate userspace logging daemon (ulogd) may be obtained from To compile it as a module, choose M here. If unsure, say N. config IP_NF_TARGET_TCPMSS tristate "TCPMSS target support" depends on IP_NF_IPTABLES ---help--- This option adds a `TCPMSS' target, which allows you to alter the MSS value of TCP SYN packets, to control the maximum size for that connection (usually limiting it to your outgoing interface's MTU minus 40). This is used to overcome criminally braindead ISPs or servers which block ICMP Fragmentation Needed packets. The symptoms of this problem are that everything works fine from your Linux firewall/router, but machines behind it can never exchange large packets: 1) Web browsers connect, then hang with no data received. 2) Small mail works fine, but large emails hang. 3) ssh works fine, but scp hangs after initial handshaking. Workaround: activate this option and add a rule to your firewall configuration like: iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN \ -j TCPMSS --clamp-mss-to-pmtu To compile it as a module, choose M here. If unsure, say N. # NAT + specific targets config IP_NF_NAT tristate "Full NAT" depends on IP_NF_IPTABLES && IP_NF_CONNTRACK help The Full NAT option allows masquerading, port forwarding and other forms of full Network Address Port Translation. It is controlled by the `nat' table in iptables: see the man page for iptables(8). To compile it as a module, choose M here. If unsure, say N. config IP_NF_NAT_NEEDED bool depends on IP_NF_NAT != n default y config IP_NF_TARGET_MASQUERADE tristate "MASQUERADE target support" depends on IP_NF_NAT help Masquerading is a special case of NAT: all outgoing connections are changed to seem to come from a particular interface's address, and if the interface goes down, those connections are lost. This is only useful for dialup accounts with dynamic IP address (ie. your IP address will be different on next dialup). To compile it as a module, choose M here. If unsure, say N. config IP_NF_TARGET_REDIRECT tristate "REDIRECT target support" depends on IP_NF_NAT help REDIRECT is a special case of NAT: all incoming connections are mapped onto the incoming interface's address, causing the packets to come to the local machine instead of passing through. This is useful for transparent proxies. To compile it as a module, choose M here. If unsure, say N. config IP_NF_TARGET_NETMAP tristate "NETMAP target support" depends on IP_NF_NAT help NETMAP is an implementation of static 1:1 NAT mapping of network addresses. It maps the network address part, while keeping the host address part intact. It is similar to Fast NAT, except that Netfilter's connection tracking doesn't work well with Fast NAT. To compile it as a module, choose M here. If unsure, say N. config IP_NF_TARGET_SAME tristate "SAME target support" depends on IP_NF_NAT help This option adds a `SAME' target, which works like the standard SNAT target, but attempts to give clients the same IP for all connections. To compile it as a module, choose M here. If unsure, say N. config IP_NF_NAT_SNMP_BASIC tristate "Basic SNMP-ALG support (EXPERIMENTAL)" depends on EXPERIMENTAL && IP_NF_NAT ---help--- This module implements an Application Layer Gateway (ALG) for SNMP payloads. In conjunction with NAT, it allows a network management system to access multiple private networks with conflicting addresses. It works by modifying IP addresses inside SNMP payloads to match IP-layer NAT mapping. This is the "basic" form of SNMP-ALG, as described in RFC 2962 To compile it as a module, choose M here. If unsure, say N. config IP_NF_NAT_IRC tristate depends on IP_NF_IPTABLES!=n && IP_NF_CONNTRACK!=n && IP_NF_NAT!=n default IP_NF_NAT if IP_NF_IRC=y default m if IP_NF_IRC=m # If they want FTP, set to $CONFIG_IP_NF_NAT (m or y), # or $CONFIG_IP_NF_FTP (m or y), whichever is weaker. Argh. config IP_NF_NAT_FTP tristate depends on IP_NF_IPTABLES!=n && IP_NF_CONNTRACK!=n && IP_NF_NAT!=n default IP_NF_NAT if IP_NF_FTP=y default m if IP_NF_FTP=m config IP_NF_NAT_TFTP tristate depends on IP_NF_IPTABLES!=n && IP_NF_CONNTRACK!=n && IP_NF_NAT!=n default IP_NF_NAT if IP_NF_TFTP=y default m if IP_NF_TFTP=m config IP_NF_NAT_AMANDA tristate depends on IP_NF_IPTABLES!=n && IP_NF_CONNTRACK!=n && IP_NF_NAT!=n default IP_NF_NAT if IP_NF_AMANDA=y default m if IP_NF_AMANDA=m # mangle + specific targets config IP_NF_MANGLE tristate "Packet mangling" depends on IP_NF_IPTABLES help This option adds a `mangle' table to iptables: see the man page for iptables(8). This table is used for various packet alterations which can effect how the packet is routed. To compile it as a module, choose M here. If unsure, say N. config IP_NF_TARGET_TOS tristate "TOS target support" depends on IP_NF_MANGLE help This option adds a `TOS' target, which allows you to create rules in the `mangle' table which alter the Type Of Service field of an IP packet prior to routing. To compile it as a module, choose M here. If unsure, say N. config IP_NF_TARGET_ECN tristate "ECN target support" depends on IP_NF_MANGLE ---help--- This option adds a `ECN' target, which can be used in the iptables mangle table. You can use this target to remove the ECN bits from the IPv4 header of an IP packet. This is particularly useful, if you need to work around existing ECN blackholes on the internet, but don't want to disable ECN support in general. To compile it as a module, choose M here. If unsure, say N. config IP_NF_TARGET_DSCP tristate "DSCP target support" depends on IP_NF_MANGLE help This option adds a `DSCP' match, which allows you to match against the IPv4 header DSCP field (DSCP codepoint). The DSCP codepoint can have any value between 0x0 and 0x4f. To compile it as a module, choose M here. If unsure, say N. config IP_NF_TARGET_MARK tristate "MARK target support" depends on IP_NF_MANGLE help This option adds a `MARK' target, which allows you to create rules in the `mangle' table which alter the netfilter mark (nfmark) field associated with the packet prior to routing. This can change the routing method (see `Use netfilter MARK value as routing key') and can also be used by other subsystems to change their behavior. To compile it as a module, choose M here. If unsure, say N. config IP_NF_TARGET_CLASSIFY tristate "CLASSIFY target support" depends on IP_NF_MANGLE help This option adds a `CLASSIFY' target, which enables the user to set the priority of a packet. Some qdiscs can use this value for classification, among these are: atm, cbq, dsmark, pfifo_fast, htb, prio To compile it as a module, choose M here. If unsure, say N. config IP_NF_TARGET_TTL tristate 'TTL target support' depends on IP_NF_MANGLE help This option adds a `TTL' target, which enables the user to modify the TTL value of the IP header. While it is safe to decrement/lower the TTL, this target also enables functionality to increment and set the TTL value of the IP header to arbitrary values. This is EXTREMELY DANGEROUS since you can easily create immortal packets that loop forever on the network. To compile it as a module, choose M here. If unsure, say N. config IP_NF_TARGET_CONNMARK tristate 'CONNMARK target support' depends on IP_NF_CONNTRACK_MARK && IP_NF_MANGLE help This option adds a `CONNMARK' target, which allows one to manipulate the connection mark value. Similar to the MARK target, but affects the connection mark value rather than the packet mark value. If you want to compile it as a module, say M here and read . The module will be called ipt_CONNMARK.o. If unsure, say `N'. config IP_NF_TARGET_CLUSTERIP tristate "CLUSTERIP target support (EXPERIMENTAL)" depends on IP_NF_CONNTRACK_MARK && IP_NF_IPTABLES && EXPERIMENTAL help The CLUSTERIP target allows you to build load-balancing clusters of network servers without having a dedicated load-balancing router/server/switch. To compile it as a module, choose M here. If unsure, say N. # raw + specific targets config IP_NF_RAW tristate 'raw table support (required for NOTRACK/TRACE)' depends on IP_NF_IPTABLES help This option adds a `raw' table to iptables. This table is the very first in the netfilter framework and hooks in at the PREROUTING and OUTPUT chains. If you want to compile it as a module, say M here and read . If unsure, say `N'. config IP_NF_TARGET_NOTRACK tristate 'NOTRACK target support' depends on IP_NF_RAW depends on IP_NF_CONNTRACK help The NOTRACK target allows a select rule to specify which packets *not* to enter the conntrack/NAT subsystem with all the consequences (no ICMP error tracking, no protocol helpers for the selected packets). If you want to compile it as a module, say M here and read . If unsure, say `N'. # ARP tables config IP_NF_ARPTABLES tristate "ARP tables support" help arptables is a general, extensible packet identification framework. The ARP packet filtering and mangling (manipulation)subsystems use this: say Y or M here if you want to use either of those. To compile it as a module, choose M here. If unsure, say N. config IP_NF_ARPFILTER tristate "ARP packet filtering" depends on IP_NF_ARPTABLES help ARP packet filtering defines a table `filter', which has a series of rules for simple ARP packet filtering at local input and local output. On a bridge, you can also specify filtering rules for forwarded ARP packets. See the man page for arptables(8). To compile it as a module, choose M here. If unsure, say N. config IP_NF_ARP_MANGLE tristate "ARP payload mangling" depends on IP_NF_ARPTABLES help Allows altering the ARP packet payload: source and destination hardware and network addresses. config IP_NF_CONNTRACK_NETLINK tristate 'Connection tracking netlink interface' depends on IP_NF_CONNTRACK && NETFILTER_NETLINK help This option enables support for a netlink-based userspace interface endmenu