# SPDX-License-Identifier: GPL-2.0-only menu "Core Netfilter Configuration" depends on INET && NETFILTER config NETFILTER_INGRESS bool "Netfilter ingress support" default y select NET_INGRESS help This allows you to classify packets from ingress using the Netfilter infrastructure. config NETFILTER_EGRESS bool "Netfilter egress support" default y select NET_EGRESS help This allows you to classify packets before transmission using the Netfilter infrastructure. config NETFILTER_SKIP_EGRESS def_bool NETFILTER_EGRESS && (NET_CLS_ACT || IFB) config NETFILTER_NETLINK tristate config NETFILTER_FAMILY_BRIDGE bool config NETFILTER_FAMILY_ARP bool config NETFILTER_BPF_LINK def_bool BPF_SYSCALL config NETFILTER_NETLINK_HOOK tristate "Netfilter base hook dump support" depends on NETFILTER_ADVANCED depends on NF_TABLES select NETFILTER_NETLINK help If this option is enabled, the kernel will include support to list the base netfilter hooks via NFNETLINK. This is helpful for debugging. config NETFILTER_NETLINK_ACCT tristate "Netfilter NFACCT over NFNETLINK interface" depends on NETFILTER_ADVANCED select NETFILTER_NETLINK help If this option is enabled, the kernel will include support for extended accounting via NFNETLINK. config NETFILTER_NETLINK_QUEUE tristate "Netfilter NFQUEUE over NFNETLINK interface" depends on NETFILTER_ADVANCED select NETFILTER_NETLINK help If this option is enabled, the kernel will include support for queueing packets via NFNETLINK. config NETFILTER_NETLINK_LOG tristate "Netfilter LOG over NFNETLINK interface" default m if NETFILTER_ADVANCED=n select NETFILTER_NETLINK help If this option is enabled, the kernel will include support for logging packets via NFNETLINK. This obsoletes the existing ipt_ULOG and ebg_ulog mechanisms, and is also scheduled to replace the old syslog-based ipt_LOG and ip6t_LOG modules. config NETFILTER_NETLINK_OSF tristate "Netfilter OSF over NFNETLINK interface" depends on NETFILTER_ADVANCED select NETFILTER_NETLINK help If this option is enabled, the kernel will include support for passive OS fingerprint via NFNETLINK. config NF_CONNTRACK tristate "Netfilter connection tracking support" default m if NETFILTER_ADVANCED=n select NF_DEFRAG_IPV4 select NF_DEFRAG_IPV6 if IPV6 != n 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. 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 NF_LOG_SYSLOG tristate "Syslog packet logging" default m if NETFILTER_ADVANCED=n help This option enable support for packet logging via syslog. It supports IPv4, IPV6, ARP and common transport protocols such as TCP and UDP. This is a simpler but less flexible logging method compared to CONFIG_NETFILTER_NETLINK_LOG. If both are enabled the backend to use can be configured at run-time by means of per-address-family sysctl tunables. if NF_CONNTRACK config NETFILTER_CONNCOUNT tristate config NF_CONNTRACK_MARK bool 'Connection mark tracking support' depends on NETFILTER_ADVANCED 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 NF_CONNTRACK_SECMARK bool 'Connection tracking security mark support' depends on NETWORK_SECMARK default y if NETFILTER_ADVANCED=n help This option enables security markings to be applied to connections. Typically they are copied to connections from packets using the CONNSECMARK target and copied back from connections to packets with the same target, with the packets being originally labeled via SECMARK. If unsure, say 'N'. config NF_CONNTRACK_ZONES bool 'Connection tracking zones' depends on NETFILTER_ADVANCED help This option enables support for connection tracking zones. Normally, each connection needs to have a unique system wide identity. Connection tracking zones allow to have multiple connections using the same identity, as long as they are contained in different zones. If unsure, say `N'. config NF_CONNTRACK_PROCFS bool "Supply CT list in procfs (OBSOLETE)" depends on PROC_FS help This option enables for the list of known conntrack entries to be shown in procfs under net/netfilter/nf_conntrack. This is considered obsolete in favor of using the conntrack(8) tool which uses Netlink. config NF_CONNTRACK_EVENTS bool "Connection tracking events" depends on NETFILTER_ADVANCED 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 NF_CONNTRACK_TIMEOUT bool 'Connection tracking timeout' depends on NETFILTER_ADVANCED help This option enables support for connection tracking timeout extension. This allows you to attach timeout policies to flow via the CT target. If unsure, say `N'. config NF_CONNTRACK_TIMESTAMP bool 'Connection tracking timestamping' depends on NETFILTER_ADVANCED help This option enables support for connection tracking timestamping. This allows you to store the flow start-time and to obtain the flow-stop time (once it has been destroyed) via Connection tracking events. If unsure, say `N'. config NF_CONNTRACK_LABELS bool "Connection tracking labels" help This option enables support for assigning user-defined flag bits to connection tracking entries. It can be used with xtables connlabel match and the nftables ct expression. config NF_CONNTRACK_OVS bool config NF_CT_PROTO_DCCP bool 'DCCP protocol connection tracking support' depends on NETFILTER_ADVANCED default y help With this option enabled, the layer 3 independent connection tracking code will be able to do state tracking on DCCP connections. If unsure, say Y. config NF_CT_PROTO_GRE bool config NF_CT_PROTO_SCTP bool 'SCTP protocol connection tracking support' depends on NETFILTER_ADVANCED default y select LIBCRC32C help With this option enabled, the layer 3 independent connection tracking code will be able to do state tracking on SCTP connections. If unsure, say Y. config NF_CT_PROTO_UDPLITE bool 'UDP-Lite protocol connection tracking support' depends on NETFILTER_ADVANCED default y help With this option enabled, the layer 3 independent connection tracking code will be able to do state tracking on UDP-Lite connections. If unsure, say Y. config NF_CONNTRACK_AMANDA tristate "Amanda backup protocol support" depends on NETFILTER_ADVANCED select TEXTSEARCH select TEXTSEARCH_KMP help If you are running the Amanda backup package <http://www.amanda.org/> 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 N. config NF_CONNTRACK_FTP tristate "FTP protocol support" default m if NETFILTER_ADVANCED=n 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. This is FTP support on Layer 3 independent connection tracking. To compile it as a module, choose M here. If unsure, say N. config NF_CONNTRACK_H323 tristate "H.323 protocol support" depends on IPV6 || IPV6=n depends on NETFILTER_ADVANCED help H.323 is a VoIP signalling protocol from ITU-T. As one of the most important VoIP protocols, it is widely used by voice hardware and software including voice gateways, IP phones, Netmeeting, OpenPhone, Gnomemeeting, etc. With this module you can support H.323 on a connection tracking/NAT firewall. This module supports RAS, Fast Start, H.245 Tunnelling, Call Forwarding, RTP/RTCP and T.120 based audio, video, fax, chat, whiteboard, file transfer, etc. For more information, please visit http://nath323.sourceforge.net/. To compile it as a module, choose M here. If unsure, say N. config NF_CONNTRACK_IRC tristate "IRC protocol support" default m if NETFILTER_ADVANCED=n 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 N. config NF_CONNTRACK_BROADCAST tristate config NF_CONNTRACK_NETBIOS_NS tristate "NetBIOS name service protocol support" select NF_CONNTRACK_BROADCAST 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: <BROADCAST,MULTICAST,UP> 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 NF_CONNTRACK_SNMP tristate "SNMP service protocol support" depends on NETFILTER_ADVANCED select NF_CONNTRACK_BROADCAST help SNMP 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 SNMP service requests and the corresponding responses. It relies on correct IP address configuration, specifically netmask and broadcast address. To compile it as a module, choose M here. If unsure, say N. config NF_CONNTRACK_PPTP tristate "PPtP protocol support" depends on NETFILTER_ADVANCED select NF_CT_PROTO_GRE help This module adds support for PPTP (Point to Point Tunnelling Protocol, RFC2637) connection tracking and NAT. If you are running PPTP sessions over a stateful firewall or NAT box, you may want to enable this feature. Please note that not all PPTP modes of operation are supported yet. Specifically these limitations exist: - Blindly assumes that control connections are always established in PNS->PAC direction. This is a violation of RFC2637. - Only supports a single call within each session To compile it as a module, choose M here. If unsure, say N. config NF_CONNTRACK_SANE tristate "SANE protocol support" depends on NETFILTER_ADVANCED help SANE is a protocol for remote access to scanners as implemented by the 'saned' daemon. Like FTP, it uses separate control and data connections. With this module you can support SANE on a connection tracking firewall. To compile it as a module, choose M here. If unsure, say N. config NF_CONNTRACK_SIP tristate "SIP protocol support" default m if NETFILTER_ADVANCED=n help SIP is an application-layer control protocol that can establish, modify, and terminate multimedia sessions (conferences) such as Internet telephony calls. With the nf_conntrack_sip and the nf_nat_sip modules you can support the protocol on a connection tracking/NATing firewall. To compile it as a module, choose M here. If unsure, say N. config NF_CONNTRACK_TFTP tristate "TFTP protocol support" depends on NETFILTER_ADVANCED 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 N. config NF_CT_NETLINK tristate 'Connection tracking netlink interface' select NETFILTER_NETLINK default m if NETFILTER_ADVANCED=n help This option enables support for a netlink-based userspace interface config NF_CT_NETLINK_TIMEOUT tristate 'Connection tracking timeout tuning via Netlink' select NETFILTER_NETLINK depends on NETFILTER_ADVANCED depends on NF_CONNTRACK_TIMEOUT help This option enables support for connection tracking timeout fine-grain tuning. This allows you to attach specific timeout policies to flows, instead of using the global timeout policy. If unsure, say `N'. config NF_CT_NETLINK_HELPER tristate 'Connection tracking helpers in user-space via Netlink' select NETFILTER_NETLINK depends on NF_CT_NETLINK depends on NETFILTER_NETLINK_QUEUE depends on NETFILTER_NETLINK_GLUE_CT depends on NETFILTER_ADVANCED help This option enables the user-space connection tracking helpers infrastructure. If unsure, say `N'. config NETFILTER_NETLINK_GLUE_CT bool "NFQUEUE and NFLOG integration with Connection Tracking" default n depends on (NETFILTER_NETLINK_QUEUE || NETFILTER_NETLINK_LOG) && NF_CT_NETLINK help If this option is enabled, NFQUEUE and NFLOG can include Connection Tracking information together with the packet is the enqueued via NFNETLINK. config NF_NAT tristate "Network Address Translation support" depends on NF_CONNTRACK default m if NETFILTER_ADVANCED=n help The NAT option allows masquerading, port forwarding and other forms of full Network Address Port Translation. This can be controlled by iptables, ip6tables or nft. config NF_NAT_AMANDA tristate depends on NF_CONNTRACK && NF_NAT default NF_NAT && NF_CONNTRACK_AMANDA config NF_NAT_FTP tristate depends on NF_CONNTRACK && NF_NAT default NF_NAT && NF_CONNTRACK_FTP config NF_NAT_IRC tristate depends on NF_CONNTRACK && NF_NAT default NF_NAT && NF_CONNTRACK_IRC config NF_NAT_SIP tristate depends on NF_CONNTRACK && NF_NAT default NF_NAT && NF_CONNTRACK_SIP config NF_NAT_TFTP tristate depends on NF_CONNTRACK && NF_NAT default NF_NAT && NF_CONNTRACK_TFTP config NF_NAT_REDIRECT bool config NF_NAT_MASQUERADE bool config NF_NAT_OVS bool config NETFILTER_SYNPROXY tristate endif # NF_CONNTRACK config NF_TABLES select NETFILTER_NETLINK select LIBCRC32C tristate "Netfilter nf_tables support" help nftables is the new packet classification framework that intends to replace the existing {ip,ip6,arp,eb}_tables infrastructure. It provides a pseudo-state machine with an extensible instruction-set (also known as expressions) that the userspace 'nft' utility (https://www.netfilter.org/projects/nftables) uses to build the rule-set. It also comes with the generic set infrastructure that allows you to construct mappings between matchings and actions for performance lookups. To compile it as a module, choose M here. if NF_TABLES config NF_TABLES_INET depends on IPV6 select NF_TABLES_IPV4 select NF_TABLES_IPV6 bool "Netfilter nf_tables mixed IPv4/IPv6 tables support" help This option enables support for a mixed IPv4/IPv6 "inet" table. config NF_TABLES_NETDEV bool "Netfilter nf_tables netdev tables support" help This option enables support for the "netdev" table. config NFT_NUMGEN tristate "Netfilter nf_tables number generator module" help This option adds the number generator expression used to perform incremental counting and random numbers bound to a upper limit. config NFT_CT depends on NF_CONNTRACK tristate "Netfilter nf_tables conntrack module" help This option adds the "ct" expression that you can use to match connection tracking information such as the flow state. config NFT_FLOW_OFFLOAD depends on NF_CONNTRACK && NF_FLOW_TABLE tristate "Netfilter nf_tables hardware flow offload module" help This option adds the "flow_offload" expression that you can use to choose what flows are placed into the hardware. config NFT_CONNLIMIT tristate "Netfilter nf_tables connlimit module" depends on NF_CONNTRACK depends on NETFILTER_ADVANCED select NETFILTER_CONNCOUNT help This option adds the "connlimit" expression that you can use to ratelimit rule matchings per connections. config NFT_LOG tristate "Netfilter nf_tables log module" help This option adds the "log" expression that you can use to log packets matching some criteria. config NFT_LIMIT tristate "Netfilter nf_tables limit module" help This option adds the "limit" expression that you can use to ratelimit rule matchings. config NFT_MASQ depends on NF_CONNTRACK depends on NF_NAT select NF_NAT_MASQUERADE tristate "Netfilter nf_tables masquerade support" help This option adds the "masquerade" expression that you can use to perform NAT in the masquerade flavour. config NFT_REDIR depends on NF_CONNTRACK depends on NF_NAT tristate "Netfilter nf_tables redirect support" select NF_NAT_REDIRECT help This options adds the "redirect" expression that you can use to perform NAT in the redirect flavour. config NFT_NAT depends on NF_CONNTRACK select NF_NAT depends on NF_TABLES_IPV4 || NF_TABLES_IPV6 tristate "Netfilter nf_tables nat module" help This option adds the "nat" expression that you can use to perform typical Network Address Translation (NAT) packet transformations. config NFT_TUNNEL tristate "Netfilter nf_tables tunnel module" help This option adds the "tunnel" expression that you can use to set tunneling policies. config NFT_QUEUE depends on NETFILTER_NETLINK_QUEUE tristate "Netfilter nf_tables queue module" help This is required if you intend to use the userspace queueing infrastructure (also known as NFQUEUE) from nftables. config NFT_QUOTA tristate "Netfilter nf_tables quota module" help This option adds the "quota" expression that you can use to match enforce bytes quotas. config NFT_REJECT default m if NETFILTER_ADVANCED=n tristate "Netfilter nf_tables reject support" depends on !NF_TABLES_INET || (IPV6!=m || m) help This option adds the "reject" expression that you can use to explicitly deny and notify via TCP reset/ICMP informational errors unallowed traffic. config NFT_REJECT_INET depends on NF_TABLES_INET default NFT_REJECT tristate config NFT_COMPAT depends on NETFILTER_XTABLES tristate "Netfilter x_tables over nf_tables module" help This is required if you intend to use any of existing x_tables match/target extensions over the nf_tables framework. config NFT_HASH tristate "Netfilter nf_tables hash module" help This option adds the "hash" expression that you can use to perform a hash operation on registers. config NFT_FIB tristate config NFT_FIB_INET depends on NF_TABLES_INET depends on NFT_FIB_IPV4 depends on NFT_FIB_IPV6 tristate "Netfilter nf_tables fib inet support" help This option allows using the FIB expression from the inet table. The lookup will be delegated to the IPv4 or IPv6 FIB depending on the protocol of the packet. config NFT_XFRM tristate "Netfilter nf_tables xfrm/IPSec security association matching" depends on XFRM help This option adds an expression that you can use to extract properties of a packets security association. config NFT_SOCKET tristate "Netfilter nf_tables socket match support" depends on IPV6 || IPV6=n select NF_SOCKET_IPV4 select NF_SOCKET_IPV6 if NF_TABLES_IPV6 help This option allows matching for the presence or absence of a corresponding socket and its attributes. config NFT_OSF tristate "Netfilter nf_tables passive OS fingerprint support" depends on NETFILTER_ADVANCED select NETFILTER_NETLINK_OSF help This option allows matching packets from an specific OS. config NFT_TPROXY tristate "Netfilter nf_tables tproxy support" depends on IPV6 || IPV6=n select NF_DEFRAG_IPV4 select NF_DEFRAG_IPV6 if NF_TABLES_IPV6 select NF_TPROXY_IPV4 select NF_TPROXY_IPV6 if NF_TABLES_IPV6 help This makes transparent proxy support available in nftables. config NFT_SYNPROXY tristate "Netfilter nf_tables SYNPROXY expression support" depends on NF_CONNTRACK && NETFILTER_ADVANCED select NETFILTER_SYNPROXY select SYN_COOKIES help The SYNPROXY expression allows you to intercept TCP connections and establish them using syncookies before they are passed on to the server. This allows to avoid conntrack and server resource usage during SYN-flood attacks. if NF_TABLES_NETDEV config NF_DUP_NETDEV tristate "Netfilter packet duplication support" help This option enables the generic packet duplication infrastructure for Netfilter. config NFT_DUP_NETDEV tristate "Netfilter nf_tables netdev packet duplication support" select NF_DUP_NETDEV help This option enables packet duplication for the "netdev" family. config NFT_FWD_NETDEV tristate "Netfilter nf_tables netdev packet forwarding support" select NF_DUP_NETDEV help This option enables packet forwarding for the "netdev" family. config NFT_FIB_NETDEV depends on NFT_FIB_IPV4 depends on NFT_FIB_IPV6 tristate "Netfilter nf_tables netdev fib lookups support" help This option allows using the FIB expression from the netdev table. The lookup will be delegated to the IPv4 or IPv6 FIB depending on the protocol of the packet. config NFT_REJECT_NETDEV depends on NFT_REJECT_IPV4 depends on NFT_REJECT_IPV6 tristate "Netfilter nf_tables netdev REJECT support" help This option enables the REJECT support from the netdev table. The return packet generation will be delegated to the IPv4 or IPv6 ICMP or TCP RST implementation depending on the protocol of the packet. endif # NF_TABLES_NETDEV endif # NF_TABLES config NF_FLOW_TABLE_INET tristate "Netfilter flow table mixed IPv4/IPv6 module" depends on NF_FLOW_TABLE help This option adds the flow table mixed IPv4/IPv6 support. To compile it as a module, choose M here. config NF_FLOW_TABLE tristate "Netfilter flow table module" depends on NETFILTER_INGRESS depends on NF_CONNTRACK depends on NF_TABLES help This option adds the flow table core infrastructure. To compile it as a module, choose M here. config NF_FLOW_TABLE_PROCFS bool "Supply flow table statistics in procfs" depends on NF_FLOW_TABLE depends on PROC_FS help This option enables for the flow table offload statistics to be shown in procfs under net/netfilter/nf_flowtable. config NETFILTER_XTABLES tristate "Netfilter Xtables support (required for ip_tables)" default m if NETFILTER_ADVANCED=n help This is required if you intend to use any of ip_tables, ip6_tables or arp_tables. if NETFILTER_XTABLES config NETFILTER_XTABLES_COMPAT bool "Netfilter Xtables 32bit support" depends on COMPAT help This option provides a translation layer to run 32bit arp,ip(6),ebtables binaries on 64bit kernels. If unsure, say N. comment "Xtables combined modules" config NETFILTER_XT_MARK tristate 'nfmark target and match support' default m if NETFILTER_ADVANCED=n help This option adds the "MARK" target and "mark" match. Netfilter mark matching allows you to match packets based on the "nfmark" value in the packet. The target allows you to create rules in the "mangle" table which alter the netfilter mark (nfmark) field associated with the packet. Prior to routing, the nfmark can influence the routing method and can also be used by other subsystems to change their behavior. config NETFILTER_XT_CONNMARK tristate 'ctmark target and match support' depends on NF_CONNTRACK depends on NETFILTER_ADVANCED select NF_CONNTRACK_MARK help This option adds the "CONNMARK" target and "connmark" match. Netfilter allows you to store a mark value per connection (a.k.a. ctmark), similarly to the packet mark (nfmark). Using this target and match, you can set and match on this mark. config NETFILTER_XT_SET tristate 'set target and match support' depends on IP_SET depends on NETFILTER_ADVANCED help This option adds the "SET" target and "set" match. Using this target and match, you can add/delete and match elements in the sets created by ipset(8). To compile it as a module, choose M here. If unsure, say N. # alphabetically ordered list of targets comment "Xtables targets" config NETFILTER_XT_TARGET_AUDIT tristate "AUDIT target support" depends on AUDIT depends on NETFILTER_ADVANCED help This option adds a 'AUDIT' target, which can be used to create audit records for packets dropped/accepted. To compileit as a module, choose M here. If unsure, say N. config NETFILTER_XT_TARGET_CHECKSUM tristate "CHECKSUM target support" depends on IP_NF_MANGLE || IP6_NF_MANGLE depends on NETFILTER_ADVANCED help This option adds a `CHECKSUM' target, which can be used in the iptables mangle table to work around buggy DHCP clients in virtualized environments. Some old DHCP clients drop packets because they are not aware that the checksum would normally be offloaded to hardware and thus should be considered valid. This target can be used to fill in the checksum using iptables when such packets are sent via a virtual network device. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_TARGET_CLASSIFY tristate '"CLASSIFY" target support' depends on NETFILTER_ADVANCED 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 NETFILTER_XT_TARGET_CONNMARK tristate '"CONNMARK" target support' depends on NF_CONNTRACK depends on NETFILTER_ADVANCED select NETFILTER_XT_CONNMARK help This is a backwards-compat option for the user's convenience (e.g. when running oldconfig). It selects CONFIG_NETFILTER_XT_CONNMARK (combined connmark/CONNMARK module). config NETFILTER_XT_TARGET_CONNSECMARK tristate '"CONNSECMARK" target support' depends on NF_CONNTRACK && NF_CONNTRACK_SECMARK default m if NETFILTER_ADVANCED=n help The CONNSECMARK target copies security markings from packets to connections, and restores security markings from connections to packets (if the packets are not already marked). This would normally be used in conjunction with the SECMARK target. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_TARGET_CT tristate '"CT" target support' depends on NF_CONNTRACK depends on IP_NF_RAW || IP6_NF_RAW depends on NETFILTER_ADVANCED help This options adds a `CT' target, which allows to specify initial connection tracking parameters like events to be delivered and the helper to be used. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_TARGET_DSCP tristate '"DSCP" and "TOS" target support' depends on IP_NF_MANGLE || IP6_NF_MANGLE depends on NETFILTER_ADVANCED help This option adds a `DSCP' target, which allows you to manipulate the IPv4/IPv6 header DSCP field (differentiated services codepoint). The DSCP field can have any value between 0x0 and 0x3f inclusive. It also adds the "TOS" target, which allows you to create rules in the "mangle" table which alter the Type Of Service field of an IPv4 or the Priority field of an IPv6 packet, prior to routing. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_TARGET_HL tristate '"HL" hoplimit target support' depends on IP_NF_MANGLE || IP6_NF_MANGLE depends on NETFILTER_ADVANCED help This option adds the "HL" (for IPv6) and "TTL" (for IPv4) targets, which enable the user to change the hoplimit/time-to-live value of the IP header. While it is safe to decrement the hoplimit/TTL value, the modules also allow to increment and set the hoplimit value of the header to arbitrary values. This is EXTREMELY DANGEROUS since you can easily create immortal packets that loop forever on the network. config NETFILTER_XT_TARGET_HMARK tristate '"HMARK" target support' depends on IP6_NF_IPTABLES || IP6_NF_IPTABLES=n depends on NETFILTER_ADVANCED help This option adds the "HMARK" target. The target allows you to create rules in the "raw" and "mangle" tables which set the skbuff mark by means of hash calculation within a given range. The nfmark can influence the routing method and can also be used by other subsystems to change their behaviour. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_TARGET_IDLETIMER tristate "IDLETIMER target support" depends on NETFILTER_ADVANCED help This option adds the `IDLETIMER' target. Each matching packet resets the timer associated with label specified when the rule is added. When the timer expires, it triggers a sysfs notification. The remaining time for expiration can be read via sysfs. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_TARGET_LED tristate '"LED" target support' depends on LEDS_CLASS && LEDS_TRIGGERS depends on NETFILTER_ADVANCED help This option adds a `LED' target, which allows you to blink LEDs in response to particular packets passing through your machine. This can be used to turn a spare LED into a network activity LED, which only flashes in response to FTP transfers, for example. Or you could have an LED which lights up for a minute or two every time somebody connects to your machine via SSH. You will need support for the "led" class to make this work. To create an LED trigger for incoming SSH traffic: iptables -A INPUT -p tcp --dport 22 -j LED --led-trigger-id ssh --led-delay 1000 Then attach the new trigger to an LED on your system: echo netfilter-ssh > /sys/class/leds/<ledname>/trigger For more information on the LEDs available on your system, see Documentation/leds/leds-class.rst config NETFILTER_XT_TARGET_LOG tristate "LOG target support" select NF_LOG_SYSLOG select NF_LOG_IPV6 if IP6_NF_IPTABLES default m if NETFILTER_ADVANCED=n 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 NETFILTER_XT_TARGET_MARK tristate '"MARK" target support' depends on NETFILTER_ADVANCED select NETFILTER_XT_MARK help This is a backwards-compat option for the user's convenience (e.g. when running oldconfig). It selects CONFIG_NETFILTER_XT_MARK (combined mark/MARK module). config NETFILTER_XT_NAT tristate '"SNAT and DNAT" targets support' depends on NF_NAT help This option enables the SNAT and DNAT targets. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_TARGET_NETMAP tristate '"NETMAP" target support' depends on 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. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_TARGET_NFLOG tristate '"NFLOG" target support' default m if NETFILTER_ADVANCED=n select NETFILTER_NETLINK_LOG help This option enables the NFLOG target, which allows to LOG messages through nfnetlink_log. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_TARGET_NFQUEUE tristate '"NFQUEUE" target Support' depends on NETFILTER_ADVANCED select NETFILTER_NETLINK_QUEUE help This target replaced the old obsolete QUEUE target. As opposed to QUEUE, it supports 65535 different queues, not just one. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_TARGET_NOTRACK tristate '"NOTRACK" target support (DEPRECATED)' depends on NF_CONNTRACK depends on IP_NF_RAW || IP6_NF_RAW depends on NETFILTER_ADVANCED select NETFILTER_XT_TARGET_CT config NETFILTER_XT_TARGET_RATEEST tristate '"RATEEST" target support' depends on NETFILTER_ADVANCED help This option adds a `RATEEST' target, which allows to measure rates similar to TC estimators. The `rateest' match can be used to match on the measured rates. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_TARGET_REDIRECT tristate "REDIRECT target support" depends on NF_NAT select NF_NAT_REDIRECT 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 NETFILTER_XT_TARGET_MASQUERADE tristate "MASQUERADE target support" depends on NF_NAT default m if NETFILTER_ADVANCED=n select NF_NAT_MASQUERADE 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 NETFILTER_XT_TARGET_TEE tristate '"TEE" - packet cloning to alternate destination' depends on NETFILTER_ADVANCED depends on IPV6 || IPV6=n depends on !NF_CONNTRACK || NF_CONNTRACK depends on IP6_NF_IPTABLES || !IP6_NF_IPTABLES select NF_DUP_IPV4 select NF_DUP_IPV6 if IP6_NF_IPTABLES help This option adds a "TEE" target with which a packet can be cloned and this clone be rerouted to another nexthop. config NETFILTER_XT_TARGET_TPROXY tristate '"TPROXY" target transparent proxying support' depends on NETFILTER_XTABLES depends on NETFILTER_ADVANCED depends on IPV6 || IPV6=n depends on IP6_NF_IPTABLES || IP6_NF_IPTABLES=n depends on IP_NF_MANGLE select NF_DEFRAG_IPV4 select NF_DEFRAG_IPV6 if IP6_NF_IPTABLES != n select NF_TPROXY_IPV4 select NF_TPROXY_IPV6 if IP6_NF_IPTABLES help This option adds a `TPROXY' target, which is somewhat similar to REDIRECT. It can only be used in the mangle table and is useful to redirect traffic to a transparent proxy. It does _not_ depend on Netfilter connection tracking and NAT, unlike REDIRECT. For it to work you will have to configure certain iptables rules and use policy routing. For more information on how to set it up see Documentation/networking/tproxy.rst. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_TARGET_TRACE tristate '"TRACE" target support' depends on IP_NF_RAW || IP6_NF_RAW depends on NETFILTER_ADVANCED help The TRACE target allows you to mark packets so that the kernel will log every rule which match the packets as those traverse the tables, chains, rules. If you want to compile it as a module, say M here and read <file:Documentation/kbuild/modules.rst>. If unsure, say `N'. config NETFILTER_XT_TARGET_SECMARK tristate '"SECMARK" target support' depends on NETWORK_SECMARK default m if NETFILTER_ADVANCED=n help The SECMARK target allows security marking of network packets, for use with security subsystems. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_TARGET_TCPMSS tristate '"TCPMSS" target support' depends on IPV6 || IPV6=n default m if NETFILTER_ADVANCED=n 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. config NETFILTER_XT_TARGET_TCPOPTSTRIP tristate '"TCPOPTSTRIP" target support' depends on IP_NF_MANGLE || IP6_NF_MANGLE depends on NETFILTER_ADVANCED help This option adds a "TCPOPTSTRIP" target, which allows you to strip TCP options from TCP packets. # alphabetically ordered list of matches comment "Xtables matches" config NETFILTER_XT_MATCH_ADDRTYPE tristate '"addrtype" address type match support' default m if NETFILTER_ADVANCED=n 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 <file:Documentation/kbuild/modules.rst>. If unsure, say `N'. config NETFILTER_XT_MATCH_BPF tristate '"bpf" match support' depends on NETFILTER_ADVANCED help BPF matching applies a linux socket filter to each packet and accepts those for which the filter returns non-zero. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_MATCH_CGROUP tristate '"control group" match support' depends on NETFILTER_ADVANCED depends on CGROUPS select CGROUP_NET_CLASSID help Socket/process control group matching allows you to match locally generated packets based on which net_cls control group processes belong to. config NETFILTER_XT_MATCH_CLUSTER tristate '"cluster" match support' depends on NF_CONNTRACK depends on NETFILTER_ADVANCED help This option allows you to build work-load-sharing clusters of network servers/stateful firewalls without having a dedicated load-balancing router/server/switch. Basically, this match returns true when the packet must be handled by this cluster node. Thus, all nodes see all packets and this match decides which node handles what packets. The work-load sharing algorithm is based on source address hashing. If you say Y or M here, try `iptables -m cluster --help` for more information. config NETFILTER_XT_MATCH_COMMENT tristate '"comment" match support' depends on NETFILTER_ADVANCED 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 <file:Documentation/kbuild/modules.rst>. If unsure, say `N'. config NETFILTER_XT_MATCH_CONNBYTES tristate '"connbytes" per-connection counter match support' depends on NF_CONNTRACK depends on NETFILTER_ADVANCED 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 <file:Documentation/kbuild/modules.rst>. If unsure, say `N'. config NETFILTER_XT_MATCH_CONNLABEL tristate '"connlabel" match support' select NF_CONNTRACK_LABELS depends on NF_CONNTRACK depends on NETFILTER_ADVANCED help This match allows you to test and assign userspace-defined labels names to a connection. The kernel only stores bit values - mapping names to bits is done by userspace. Unlike connmark, more than 32 flag bits may be assigned to a connection simultaneously. config NETFILTER_XT_MATCH_CONNLIMIT tristate '"connlimit" match support' depends on NF_CONNTRACK depends on NETFILTER_ADVANCED select NETFILTER_CONNCOUNT help This match allows you to match against the number of parallel connections to a server per client IP address (or address block). config NETFILTER_XT_MATCH_CONNMARK tristate '"connmark" connection mark match support' depends on NF_CONNTRACK depends on NETFILTER_ADVANCED select NETFILTER_XT_CONNMARK help This is a backwards-compat option for the user's convenience (e.g. when running oldconfig). It selects CONFIG_NETFILTER_XT_CONNMARK (combined connmark/CONNMARK module). config NETFILTER_XT_MATCH_CONNTRACK tristate '"conntrack" connection tracking match support' depends on NF_CONNTRACK default m if NETFILTER_ADVANCED=n 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 NETFILTER_XT_MATCH_CPU tristate '"cpu" match support' depends on NETFILTER_ADVANCED help CPU matching allows you to match packets based on the CPU currently handling the packet. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_MATCH_DCCP tristate '"dccp" protocol match support' depends on NETFILTER_ADVANCED default IP_DCCP 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 <file:Documentation/kbuild/modules.rst>. If unsure, say `N'. config NETFILTER_XT_MATCH_DEVGROUP tristate '"devgroup" match support' depends on NETFILTER_ADVANCED help This options adds a `devgroup' match, which allows to match on the device group a network device is assigned to. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_MATCH_DSCP tristate '"dscp" and "tos" match support' depends on NETFILTER_ADVANCED help This option adds a `DSCP' match, which allows you to match against the IPv4/IPv6 header DSCP field (differentiated services codepoint). The DSCP field can have any value between 0x0 and 0x3f inclusive. It will also add a "tos" match, which allows you to match packets based on the Type Of Service fields of the IPv4 packet (which share the same bits as DSCP). To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_MATCH_ECN tristate '"ecn" match support' depends on NETFILTER_ADVANCED help This option adds an "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 NETFILTER_XT_MATCH_ESP tristate '"esp" match support' depends on NETFILTER_ADVANCED help This match extension allows you to match a range of SPIs inside ESP header of IPSec packets. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_MATCH_HASHLIMIT tristate '"hashlimit" match support' depends on IP6_NF_IPTABLES || IP6_NF_IPTABLES=n depends on NETFILTER_ADVANCED help This option adds a `hashlimit' match. As opposed to `limit', this match dynamically creates a hash table of limit buckets, based on your selection of source/destination addresses and/or ports. It enables you to express policies like `10kpps for any given destination address' or `500pps from any given source address' with a single rule. config NETFILTER_XT_MATCH_HELPER tristate '"helper" match support' depends on NF_CONNTRACK depends on NETFILTER_ADVANCED help Helper matching allows you to match packets in dynamic connections tracked by a conntrack-helper, ie. nf_conntrack_ftp To compile it as a module, choose M here. If unsure, say Y. config NETFILTER_XT_MATCH_HL tristate '"hl" hoplimit/TTL match support' depends on NETFILTER_ADVANCED help HL matching allows you to match packets based on the hoplimit in the IPv6 header, or the time-to-live field in the IPv4 header of the packet. config NETFILTER_XT_MATCH_IPCOMP tristate '"ipcomp" match support' depends on NETFILTER_ADVANCED help This match extension allows you to match a range of CPIs(16 bits) inside IPComp header of IPSec packets. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_MATCH_IPRANGE tristate '"iprange" address range match support' depends on NETFILTER_ADVANCED help This option adds a "iprange" match, which allows you to match based on an IP address range. (Normal iptables only matches on single addresses with an optional mask.) If unsure, say M. config NETFILTER_XT_MATCH_IPVS tristate '"ipvs" match support' depends on IP_VS depends on NETFILTER_ADVANCED depends on NF_CONNTRACK help This option allows you to match against IPVS properties of a packet. If unsure, say N. config NETFILTER_XT_MATCH_L2TP tristate '"l2tp" match support' depends on NETFILTER_ADVANCED default L2TP help This option adds an "L2TP" match, which allows you to match against L2TP protocol header fields. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_MATCH_LENGTH tristate '"length" match support' depends on NETFILTER_ADVANCED 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 NETFILTER_XT_MATCH_LIMIT tristate '"limit" match support' depends on NETFILTER_ADVANCED 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 NETFILTER_XT_MATCH_MAC tristate '"mac" address match support' depends on NETFILTER_ADVANCED 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 NETFILTER_XT_MATCH_MARK tristate '"mark" match support' depends on NETFILTER_ADVANCED select NETFILTER_XT_MARK help This is a backwards-compat option for the user's convenience (e.g. when running oldconfig). It selects CONFIG_NETFILTER_XT_MARK (combined mark/MARK module). config NETFILTER_XT_MATCH_MULTIPORT tristate '"multiport" Multiple port match support' depends on NETFILTER_ADVANCED 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 NETFILTER_XT_MATCH_NFACCT tristate '"nfacct" match support' depends on NETFILTER_ADVANCED select NETFILTER_NETLINK_ACCT help This option allows you to use the extended accounting through nfnetlink_acct. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_MATCH_OSF tristate '"osf" Passive OS fingerprint match' depends on NETFILTER_ADVANCED select NETFILTER_NETLINK_OSF help This option selects the Passive OS Fingerprinting match module that allows to passively match the remote operating system by analyzing incoming TCP SYN packets. Rules and loading software can be downloaded from http://www.ioremap.net/projects/osf To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_MATCH_OWNER tristate '"owner" match support' depends on NETFILTER_ADVANCED help Socket owner matching allows you to match locally-generated packets based on who created the socket: the user or group. It is also possible to check whether a socket actually exists. config NETFILTER_XT_MATCH_POLICY tristate 'IPsec "policy" match support' depends on XFRM default m if NETFILTER_ADVANCED=n help Policy matching allows you to match packets based on the IPsec policy that was used during decapsulation/will be used during encapsulation. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_MATCH_PHYSDEV tristate '"physdev" match support' depends on BRIDGE && BRIDGE_NETFILTER depends on NETFILTER_ADVANCED 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 NETFILTER_XT_MATCH_PKTTYPE tristate '"pkttype" packet type match support' depends on NETFILTER_ADVANCED 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 NETFILTER_XT_MATCH_QUOTA tristate '"quota" match support' depends on NETFILTER_ADVANCED help This option adds a `quota' match, which allows to match on a byte counter. If you want to compile it as a module, say M here and read <file:Documentation/kbuild/modules.rst>. If unsure, say `N'. config NETFILTER_XT_MATCH_RATEEST tristate '"rateest" match support' depends on NETFILTER_ADVANCED select NETFILTER_XT_TARGET_RATEEST help This option adds a `rateest' match, which allows to match on the rate estimated by the RATEEST target. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_MATCH_REALM tristate '"realm" match support' depends on NETFILTER_ADVANCED select IP_ROUTE_CLASSID 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 <file:Documentation/kbuild/modules.rst>. If unsure, say `N'. config NETFILTER_XT_MATCH_RECENT tristate '"recent" match support' depends on NETFILTER_ADVANCED 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: <http://snowman.net/projects/ipt_recent/> config NETFILTER_XT_MATCH_SCTP tristate '"sctp" protocol match support' depends on NETFILTER_ADVANCED default IP_SCTP help With this option enabled, you will be able to use the `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 <file:Documentation/kbuild/modules.rst>. If unsure, say `N'. config NETFILTER_XT_MATCH_SOCKET tristate '"socket" match support' depends on NETFILTER_XTABLES depends on NETFILTER_ADVANCED depends on IPV6 || IPV6=n depends on IP6_NF_IPTABLES || IP6_NF_IPTABLES=n select NF_SOCKET_IPV4 select NF_SOCKET_IPV6 if IP6_NF_IPTABLES select NF_DEFRAG_IPV4 select NF_DEFRAG_IPV6 if IP6_NF_IPTABLES != n help This option adds a `socket' match, which can be used to match packets for which a TCP or UDP socket lookup finds a valid socket. It can be used in combination with the MARK target and policy routing to implement full featured non-locally bound sockets. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_MATCH_STATE tristate '"state" match support' depends on NF_CONNTRACK default m if NETFILTER_ADVANCED=n 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 NETFILTER_XT_MATCH_STATISTIC tristate '"statistic" match support' depends on NETFILTER_ADVANCED help This option adds a `statistic' match, which allows you to match on packets periodically or randomly with a given percentage. To compile it as a module, choose M here. If unsure, say N. config NETFILTER_XT_MATCH_STRING tristate '"string" match support' depends on NETFILTER_ADVANCED 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. config NETFILTER_XT_MATCH_TCPMSS tristate '"tcpmss" match support' depends on NETFILTER_ADVANCED 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 NETFILTER_XT_MATCH_TIME tristate '"time" match support' depends on NETFILTER_ADVANCED help This option adds a "time" match, which allows you to match based on the packet arrival time (at the machine which netfilter is running) on) or departure time/date (for locally generated packets). If you say Y here, try `iptables -m time --help` for more information. If you want to compile it as a module, say M here. If unsure, say N. config NETFILTER_XT_MATCH_U32 tristate '"u32" match support' depends on NETFILTER_ADVANCED help u32 allows you to extract quantities of up to 4 bytes from a packet, AND them with specified masks, shift them by specified amounts and test whether the results are in any of a set of specified ranges. The specification of what to extract is general enough to skip over headers with lengths stored in the packet, as in IP or TCP header lengths. Details and examples are in the kernel module source. endif # NETFILTER_XTABLES endmenu source "net/netfilter/ipset/Kconfig" source "net/netfilter/ipvs/Kconfig"