'\" t
.\" ȨУ1999 Matthew Wilcoxκ޸Ŀʱ˴ԭģ
.\" ޸˺޸ڣ
.\" İȨ Alian Yao, BitBIRD www.linuxforum.net 2000
.\" ޸1June 1999 Andi Kleen 
.\" $Id: arp.7,v 1.1.1.1 2000/12/27 12:24:49 BitBIRD Exp $

.TH ARP 7 "3 Jun 1999" "Linux Man Page" "Linux Աֲ" 
.SH 
arp \- LinuxARPģ 
.SH 
ЭģʵRFC826ж Address Resolution Protocol
[עTCP/IPĵ㵽һĵַתЭ]
ֱлڶӲַ Ipv4 Эַ֮ת
ûãһ㲻ֱӲģ顣

ʵϣṩԺЭķ 

û̿ʹ
.BR packet (7)
 socketsյ ARP עһ飩
һֻʹ
.BR netlink (7)
socketsûռ ARP Ļơ
Ҳͨ
.B ioctl (2)

.B PF_INET 
socketϵ
ARP  


ARP ģάһӲַЭַӳĻ档дСƣ
õĺ;ɵļ¼Entryռgarbage-collected
ռԶɾΪõļ¼ǿʹioctlsֱӲݻ壬
״涨 sysctl ڡ

޶ʱ䣨sysctlڣһִӳûп϶ʱ
ΪڲĻ¼ʧЧ
ΪٴĿ귢ݣARPѯʱarp
.B app_solicit 
Σȡ˵ MACʷʿƣַ
ʧܣҾɵMACַ֪ģ
.B ucast_solicit
ε unicast probeȻʧܣ㲥һµARP,ʱҪ
дݵĶ

 Linux ӵһַ󣬶Ҹõַָ Linux תĵַ
ҽսӿڴ˴ arp ʱLinux Զһõ
 arp ¼ھܾĿ·ɣӴ arp ¼

.SH IOCTLS
 ioctl
 
.B PF_INET
 sockets Сһָ
.B struct arpreq
ָΪǵIJ

.nf
.ta 4 20 33
struct arpreq
{
struct sockaddr arp_pa; /* Эַ(protocol address)*/
struct sockaddr arp_ha; /* Ӳַ(hardware address) */
int arp_flags; /* ־(flags) */
struct sockaddr arp_netmask; 
/* Эַ(netmask of protocol address)*/
char arp_dev[16];
};
.fi

.BR SIOCSARP ", " SIOCDARP "  " SIOCGARP
ɷֱáɾͻȡ ARP ӳ䡣úɾ ARP ӳ
ֻӵ
.B CAP_NET_ADMIN
Ȩ޵Ľ̻ЧUIDΪ0Ľִ̿С

.I arp_pa

.B AF_INET
socket
.I arp_ha
к
.IR arp_dev .
ָ豸ͬ͡
.I arp_dev
Ǹnull豸ַ

.TS
tab(:) allbox;
c s
l l.
\fIarp_flags\fR
־(flag):(meaning)
ATF_COM:(Lookup complete)
ATF_PERM:ü¼(Permanent entry)
ATF_PUBL:¼(Publish entry)
ATF_USETRAILERS:Ҫʹú׺(Trailers requested)
ATF_NETMASK:ʹ(Use a netmask)
ATF_DONTPUB:ظ(Don't answer)
.TE

.PP


.B ATF_NETMASK
־ô
.I arp_netmask
Ч 
Linux 2.2 ִ֧ ARP ¼ˣҪ0xffffffff0
ɾִarp¼ﲻʹ
ִarp¼
.B ATF_USETRAILERS
ѾʱˣӦüʹá


.SH SYSCTLS
ARP ֧һ sysctl ӿڣȫֲӿڵؽơ
 sysctl ͨ
.B /proc/sys/net/ipv4/neigh/*/*
ļʹ
.BR sysctl (2)
ӿʡϵͳÿӿڶ
/proc/sys/net/ipv4/neigh/.
ԼĿ¼`default'Ŀ¼е½豸
sysctl صʱΪλر
.TP
.B anycast_delay
 IPv6 ϢĻظӳʱ䣻
Ŀǰ֧ anycastȱʡֵΪ1롣
.TP
.B app_solicit
ʹö·㲥̽(multicast probe)ǰ
͵û϶ARP˿ڼس̽⣨probe
Ŀ(
.IR mcast_solicit 
)
ȱʡֵΪ0
.TP
.B base_reachable_time
һڼ¼һν
.IR base_reachable_time "/23*" base_reachable_time /2
֮ʱڣü¼ЧġյϲЭĿ϶
ô¼Чڽӳ
ȱʡֵ30롣
.TP
.B delay_first_probe_time
ijڲ¼Ч(stale)󣬷һ̽Ҫȴʱ䡣 ȱʡֵ5롣
.TP
.B gc_interval
ռڲ¼ü¼ռڣȱʡΪ30롣
.TP
.B gc_stale_time
һڲ¼ЧԵڡ
ڲ¼ʧЧʱڸǰٽһΡ
ȱʡֵ60롣
.TP
.B gc_thresh1
ARPٻеٲ
ռСȱʡֵ128
.TP
.B gc_thresh2
 ARP ٻеļ¼ơ
ռڿʼռǰ¼ 5 롣
ȱʡֵ 512
.TP
.B gc_thresh3
 ARP ٻе¼Ӳƣ
һٻеĿڴˣ
ռСȱʡֵ1024
.TP
.B locktime
ARP ¼ڸٻڵʱ䣨jiffy
Էֹڶܵӳ(potential mapping)ʱ
ARP ٻϵͳĵ (Ĵö)
ȱʡֵ 1 롣
.TP
.B mcast_solicit
ڰѼ¼Ϊɵִ֮ǰ
ö·㲥/㲥multicast/broadcastʽַ
ȱʡֵ3
.TP
.B proxy_delay
յһ֪Ĵ ARP ַ ARP ʱ
ڻӦǰӳٵ jiffyʱ䵥λBUGĿ
Էֹ籩ȱʡֵ0.8롣
.TP
.B proxy_qlen
ܷ ARP ַ(proxy-ARP addresses)ݰĿȱʡֵ64
.TP
.B retrans_time
طһǰĵȴ jiffyʱ䵥λBUGĿȱʡֵ1롣
.TP
.B ucast_solicit
ѯARP˿ڼسǰͼ͵̽⣨unicast probeĴ (
.IR app_solicit ).
ȱʡֵ3롣
.TP
.B unres_qlen
ÿûбĵַڶпɴŰĿȱʡֵ3.

.SH BUGS
ʱõʱ䵥λ jiffyӲϵйء
 Alpha ϣһ jiffy  1/1024 룬ϣ 1/100 롣

Ŀǰûа취ûռ䷢Ϳ϶
ζûռʵֵӵЭ
connection oriented protocols ARP ͨѶ
Ϊndisc̽MACַں NFS ʵҲͬ⡣

ֲҳҪ IPv4 淶ҹ IPv4  IPv6 Ĺܣ

.SH 汾

Linux 2.0е
.B struct arpreq

.I arp_dev
ͬʱ ioctl ĿҲıˡ Linux 2.2 н֧־ɵioctl

 Linux 2.2 Уȡ˶ arp ¼(벻0xffffffff)֧֡
ܱںõһԶ arp ȡԶ arp λ
ϵĿɵýӿڵתʹ arp ˣ



.SH 
.BR ip (7)
.PP

RFC826 ˽ ARP 
.br
RFC2461 IPv6ʹõĽڲԼ㷨

.SH "[İά]"
Alan Yao E-mail:Alan_Yao@163.net
.SH "[ݸ]"
2000/10/23
.br
.Bй Linux ̳ man ֲҳƻ : www.cmpp.net/