arp(7) Miscellaneous Information Manual arp(7) arp - ARP . RFC 826. IPv4 . . ARP packet(7). ARP netlink(7). ARP ioctl(2) AF_INET. ARP . . . ioctls /proc . ( /proc ) . TCP . MSG_CONFIRM sendmsg(2). ARP . ARP app_solicit MAC . MAC ucast_solicit . ARP . . ARP ARP . ARP. Ioctls ioctls AF_INET. struct arpreq . struct arpreq { struct sockaddr arp_pa; /* protocol address */ struct sockaddr arp_ha; /* hardware address */ int arp_flags; /* flags */ struct sockaddr arp_netmask; /* netmask of protocol address */ char arp_dev[16]; }; SIOCSARP SIOCDARP SIOCGARP ARP . ARP CAP_NET_ADMIN UID 0. arp_pa AF_INET arp_ha arp_dev. arp_dev . +-----------------------------------------------------------------------+ | arp_flags | +----------------+------------------------------------------------------+ | | | +----------------+------------------------------------------------------+ |ATF_COM | | +----------------+------------------------------------------------------+ |ATF_PERM | | +----------------+------------------------------------------------------+ |ATF_PUBL | | +----------------+------------------------------------------------------+ |ATF_USETRAILERS | | +----------------+------------------------------------------------------+ |ATF_NETMASK | | +----------------+------------------------------------------------------+ |ATF_DONTPUB | | +----------------+------------------------------------------------------+ ATF_NETMASK arp_netmask . Linux 2.2 ARP 0xffffffff 0 ARP . ATF_USETRAILERS . /proc ARP /proc . /proc/sys/net/ipv4/neigh/*/*. /proc/sys/net/ipv4/neigh/. "default" . . anycast_delay ( Linux 2.2) jiffies IPv6. Anycast . . app_solicit ( Linux 2.2) ARP netlink ( mcast_solicit). 0. base_reachable_time ( Linux 2.2) base_reachable_time/2 3*base_reachable_time/2. . 30 . base_reachable_time_ms. base_reachable_time_ms ( Linux 2.6.12) base_reachable_time . 30000 . delay_first_probe_time ( Linux 2.2) . 5 . gc_interval ( Linux 2.2) . 30 . gc_stale_time ( Linux 2.2) . . 60 . gc_thresh1 ( Linux 2.2) ARP. . 128. gc_thresh2 ( Linux 2.2) ARP. 5 . 512. gc_thresh3 ( Linux 2.2) ARP. . 1024. locktime ( Linux 2.2) jiffies ARP . ARP ( ). . mcast_solicit ( Linux 2.2) / . 3. proxy_delay ( 2.2) ARP -ARP proxy_delay . . 0.8 . proxy_qlen ( 2.2) -ARP. 64. retrans_time ( 2.2) . . retrans_time_ms. retrans_time_ms ( 2.6.12) . 1000 . ucast_solicit ( 2.2) ARP ( app_solicit). 3. unres_qlen ( 2.2) . 3. struct arpreq 2.0 arp_dev ioctl . ioctls 2.2. ARP ( 0xffffffff) 2.2. ARP ( ARP ). neigh/* 2.2. time(7). . ARP ndisc MAC . ( NFS UDP). IPv4 IPv4 IPv6. capabilities(7), ip(7), arpd(8) RFC 826 ARP. RFC 2461 IPv6 . 2.2+ IPv4 ARP IPv6 . 3 . . : . 6.18 8 2026 arp(7)