.. cfgcmd:: set interfaces {{ var0 }} {{ var2 }} {{ var3 }} {{ var5 }} {{ var6 }} ip arp-cache-timeout Once a neighbor has been found, the entry is considered to be valid for at least for this specifc time. An entry's validity will be extended if it receives positive feedback from higher level protocols. This defaults to 30 seconds. Example: .. code-block:: none set interfaces {{ var0 }} {{ var1 }} {{ var2 }} {{ var4 }} {{ var5 }} {{ var7 }} ip arp-cache-timeout 180 .. cfgcmd:: set interfaces {{ var0 }} {{ var2 }} {{ var3 }} {{ var5 }} {{ var6 }} ip disable-arp-filter If set the kernel can respond to arp requests with addresses from other interfaces. This may seem wrong but it usually makes sense, because it increases the chance of successful communication. IP addresses are owned by the complete host on Linux, not by particular interfaces. Only for more complex setups like load-balancing, does this behaviour cause problems. If not set (default) allows you to have multiple network interfaces on the same subnet, and have the ARPs for each interface be answered based on whether or not the kernel would route a packet from the ARP'd IP out that interface (therefore you must use source based routing for this to work). In other words it allows control of which cards (usually 1) will respond to an arp request. Example: .. code-block:: none set interfaces {{ var0 }} {{ var1 }} {{ var2 }} {{ var4 }} {{ var5 }} {{ var7 }} ip disable-arp-filter .. cfgcmd:: set interfaces {{ var0 }} {{ var2 }} {{ var3 }} {{ var5 }} {{ var6 }} ip disable-forwarding Configure interface-specific Host/Router behaviour. If set, the interface will switch to host mode and IPv6 forwarding will be disabled on this interface. .. code-block:: none set interfaces {{ var0 }} {{ var1 }} {{ var2 }} {{ var4 }} {{ var5 }} {{ var7 }} ip disable-forwarding .. cfgcmd:: set interfaces {{ var0 }} {{ var2 }} {{ var3 }} {{ var5 }} {{ var6 }} ip enable-arp-accept Define behavior for gratuitous ARP frames who's IP is not already present in the ARP table. If configured create new entries in the ARP table. Both replies and requests type gratuitous arp will trigger the ARP table to be updated, if this setting is on. If the ARP table already contains the IP address of the gratuitous arp frame, the arp table will be updated regardless if this setting is on or off. .. code-block:: none set interfaces {{ var0 }} {{ var1 }} {{ var2 }} {{ var4 }} {{ var5 }} {{ var7 }} ip enable-arp-accept .. cfgcmd:: set interfaces {{ var0 }} {{ var2 }} {{ var3 }} {{ var5 }} {{ var6 }} ip enable-arp-announce Define different restriction levels for announcing the local source IP address from IP packets in ARP requests sent on interface. Use any local address, configured on any interface if this is not set. If configured, try to avoid local addresses that are not in the target's subnet for this interface. This mode is useful when target hosts reachable via this interface require the source IP address in ARP requests to be part of their logical network configured on the receiving interface. When we generate the request we will check all our subnets that include the target IP and will preserve the source address if it is from such subnet. If there is no such subnet we select source address according to the rules for level 2. .. code-block:: none set interfaces {{ var0 }} {{ var1 }} {{ var2 }} {{ var4 }} {{ var5 }} {{ var7 }} ip enable-arp-announce .. cfgcmd:: set interfaces {{ var0 }} {{ var2 }} {{ var3 }} {{ var5 }} {{ var6 }} ip enable-arp-ignore Define different modes for sending replies in response to received ARP requests that resolve local target IP addresses: If configured, reply only if the target IP address is local address configured on the incoming interface. If this option is unset (default), reply for any local target IP address, configured on any interface. .. code-block:: none set interfaces {{ var0 }} {{ var1 }} {{ var2 }} {{ var4 }} {{ var5 }} {{ var7 }} ip enable-arp-ignore .. cfgcmd:: set interfaces {{ var0 }} {{ var2 }} {{ var3 }} {{ var5 }} {{ var6 }} ip enable-proxy-arp Use this command to enable proxy Address Resolution Protocol (ARP) on this interface. Proxy ARP allows an Ethernet interface to respond with its own :abbr:`MAC (Media Access Control)` address to ARP requests for destination IP addresses on subnets attached to other interfaces on the system. Subsequent packets sent to those destination IP addresses are forwarded appropriately by the system. Example: .. code-block:: none set interfaces {{ var0 }} {{ var1 }} {{ var2 }} {{ var4 }} {{ var5 }} {{ var7 }} ip enable-proxy-arp .. cfgcmd:: set interfaces {{ var0 }} {{ var2 }} {{ var3 }} {{ var5 }} {{ var6 }} ip proxy-arp-pvlan Private VLAN proxy arp. Basically allow proxy arp replies back to the same interface (from which the ARP request/solicitation was received). This is done to support (ethernet) switch features, like :rfc:`3069`, where the individual ports are NOT allowed to communicate with each other, but they are allowed to talk to the upstream router. As described in :rfc:`3069`, it is possible to allow these hosts to communicate through the upstream router by proxy_arp'ing. .. note:: Does not need to be used together with proxy_arp. This technology is known by different names: - In :rfc:`3069` it is called VLAN Aggregation - Cisco and Allied Telesyn call it Private VLAN - Hewlett-Packard call it Source-Port filtering or port-isolation - Ericsson call it MAC-Forced Forwarding (RFC Draft) .. cfgcmd:: set interfaces {{ var0 }} {{ var2 }} {{ var3 }} {{ var5 }} {{ var6 }} ip source-validation Enable policy for source validation by reversed path, as specified in :rfc:`3704`. Current recommended practice in :rfc:`3704` is to enable strict mode to prevent IP spoofing from DDos attacks. If using asymmetric routing or other complicated routing, then loose mode is recommended. - strict: Each incoming packet is tested against the FIB and if the interface is not the best reverse path the packet check will fail. By default failed packets are discarded. - loose: Each incoming packet's source address is also tested against the FIB and if the source address is not reachable via any interface the packet check will fail. - disable: No source validation