# # IP netfilter configuration # menu "IP: Netfilter Configuration" depends on INET && NETFILTER config NF_CONNTRACK_IPV4 tristate "IPv4 support for new connection tracking (EXPERIMENTAL)" depends on EXPERIMENTAL && NF_CONNTRACK ---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 IPv4 support on Layer 3 independent connection tracking. Layer 3 independent connection tracking is experimental scheme which generalize ip_conntrack to support other layer 3 protocols. To compile it as a module, choose M here. If unsure, say N. # 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_SECMARK bool 'Connection tracking security mark support' depends on IP_NF_CONNTRACK && NETWORK_SECMARK 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 IP_NF_CONNTRACK_EVENTS bool "Connection tracking events (EXPERIMENTAL)" depends on EXPERIMENTAL && 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_CONNTRACK_NETLINK tristate 'Connection tracking netlink interface (EXPERIMENTAL)' depends on EXPERIMENTAL && IP_NF_CONNTRACK && NETFILTER_NETLINK depends on IP_NF_CONNTRACK!=y || NETFILTER_NETLINK!=m depends on IP_NF_NAT=n || IP_NF_NAT help This option enables support for a netlink-based userspace interface 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 select TEXTSEARCH select TEXTSEARCH_KMP 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_PPTP tristate 'PPTP protocol support' depends on IP_NF_CONNTRACK 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. For more info, read top of the file net/ipv4/netfilter/ip_conntrack_pptp.c If you want to compile it as a module, say M here and read Documentation/modules.txt. If unsure, say `N'. config IP_NF_H323 tristate 'H.323 protocol support (EXPERIMENTAL)' depends on IP_NF_CONNTRACK && EXPERIMENTAL 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/. If you want to compile it as a module, say 'M' here and read Documentation/modules.txt. If unsure, say 'N'. config IP_NF_SIP tristate "SIP protocol support (EXPERIMENTAL)" depends on IP_NF_CONNTRACK && EXPERIMENTAL help SIP is an application-layer control protocol that can establish, modify, and terminate multimedia sessions (conferences) such as Internet telephony calls. With the ip_conntrack_sip and the ip_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 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)" depends on NETFILTER_XTABLES 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_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_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_AH tristate "AH match support" depends on IP_NF_IPTABLES help This match extension allows you to match a range of SPIs inside AH header of IPSec packets. 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_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_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_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 creates 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_STEALTH tristate "stealth match support" depends on IP_NF_IPTABLES help Enabling this option will drop all syn packets coming to unserved tcp ports as well as all packets coming to unserved udp ports. If you are using your system to route any type of packets (ie. via NAT) you should put this module at the end of your ruleset, since it will drop packets that aren't going to ports that are listening on your machine itself, it doesn't take into account that the packet might be destined for someone on your internal network if you're using NAT for instance. 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 enables the old IPv4-only "ipt_ULOG" implementation which has been obsoleted by the new "nfnetlink_log" code (see CONFIG_NETFILTER_NETLINK_LOG). 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 appropriate 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_TARGET_IDLETIMER tristate "IDLETIMER target support" depends on IP_NF_IPTABLES help This option adds a `IDLETIMER' target. Each matching packet resets the timer associated with input and/or output interfaces. Timer expiry causes kobject uevent. Idle timer can be read via sysfs. 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 config IP_NF_NAT_PPTP tristate depends on IP_NF_NAT!=n && IP_NF_PPTP!=n default IP_NF_NAT if IP_NF_PPTP=y default m if IP_NF_PPTP=m config IP_NF_NAT_H323 tristate depends on IP_NF_IPTABLES!=n && IP_NF_CONNTRACK!=n && IP_NF_NAT!=n default IP_NF_NAT if IP_NF_H323=y default m if IP_NF_H323=m config IP_NF_NAT_SIP tristate depends on IP_NF_IPTABLES!=n && IP_NF_CONNTRACK!=n && IP_NF_NAT!=n default IP_NF_NAT if IP_NF_SIP=y default m if IP_NF_SIP=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_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_CLUSTERIP tristate "CLUSTERIP target support (EXPERIMENTAL)" depends on IP_NF_MANGLE && EXPERIMENTAL depends on (IP_NF_CONNTRACK && IP_NF_CONNTRACK_MARK) || (NF_CONNTRACK_MARK && NF_CONNTRACK_IPV4) 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'. # ARP tables config IP_NF_ARPTABLES tristate "ARP tables support" depends on NETFILTER_XTABLES 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. endmenu