diff --git a/usr.sbin/arp/arp.4 b/usr.sbin/arp/arp.4 index ec513a86384b..ddc0471fea69 100644 --- a/usr.sbin/arp/arp.4 +++ b/usr.sbin/arp/arp.4 @@ -28,7 +28,7 @@ .\" @(#)arp4.4 6.5 (Berkeley) 4/18/94 .\" $FreeBSD$ .\" -.Dd June 16, 2004 +.Dd November 24, 2005 .Dt ARP 4 .Os .Sh NAME @@ -55,9 +55,10 @@ ARP will queue at most one packet while waiting for a response to a mapping request; only the most recently ``transmitted'' packet is kept. If the target host does not respond after several requests, -the host is considered to be down for a short period (normally 20 seconds), -allowing an error to be returned to transmission attempts during this -interval. +the host is considered to be down allowing an error to be returned to +transmission attempts. +Further demand for this mapping causes ARP request retransmissions, that +are ratelimited to one packet per second. The error is .Er EHOSTDOWN for a non-responding destination host, and @@ -75,11 +76,6 @@ causing routes to individual hosts on that network to be created on demand. These routes time out periodically (normally 20 minutes after validated; entries are not validated when not in use). -An entry for a host which is not responding is a -.Dq reject -route (one with the -.Li RTF_REJECT -flag set). .Pp ARP entries may be added, deleted or changed with the .Xr arp 8 @@ -109,12 +105,33 @@ However, the .Dq "proxy all" feature causes the local host to act as a proxy for .Em all -hosts. +hosts reachable through some other network interface, +different from the one the request came in from. It may be enabled by setting the .Xr sysctl 8 MIB variable .Va net.link.ether.inet.proxyall to 1. +.Sh MIB Variables +The ARP protocol implements a number of configrable variables in +.Va net.link.ether.inet +branch +of the +.Xr sysctl 3 +MIB. +.Bl -tag +.It Va prune_intvl +How frequently the ARP cache is cleaned from expired entries. +.It Va max_age +How long an ARP entry is held in the cache until it needs to be refreshed. +.It Va maxtries +Number of retransmits before host is considered down and error is returned. +.It Va useloopback +If an ARP entry is added for local address, force the traffic to go through +the loopback interface. +.It Va proxyall +Enables ARP proxying for all hosts on net. +.El .Sh DIAGNOSTICS .Em "arp: %x:%x:%x:%x:%x:%x is using my IP address %d.%d.%d.%d!" : ARP has discovered another host on the local network which responds to @@ -122,12 +139,12 @@ mapping requests for its own Internet address with a different Ethernet address, generally indicating that two hosts are attempting to use the same Internet address. .Pp -.Em "arp: ether address is broadcast for IP address %d.%d.%d.%d!" : +.Em "arp: link address is broadcast for IP address %d.%d.%d.%d!" : ARP requested information for a host, and received an answer indicating that the host's ethernet address is the ethernet broadcast address. This indicates a misconfigured or broken device. .Pp -.Em "arp: %d.%d.%d.%d moved from %x:%x:%x:%x:%x:%x to %x:%x:%x:%x:%x:%x" : +.Em "arp: %d.%d.%d.%d moved from %x:%x:%x:%x:%x:%x to %x:%x:%x:%x:%x:%x on %s" : ARP had a cached value for the ethernet address of the referenced host, but received a reply indicating that the host is at a new address. This can happen normally when host hardware addresses change,