From 478df1d534e9b1ca86261fcef37b46cc7b4c8f17 Mon Sep 17 00:00:00 2001 From: Gleb Smirnoff Date: Mon, 3 Sep 2012 14:29:28 +0000 Subject: [PATCH] Provide a sysctl switch that allows to install ARP entries with multicast bit set. FreeBSD refuses to install such entries since 9.0, and this broke installations running Microsoft NLB, which are violating standards. Tested by: Tarasov Oleg --- sys/netinet/if_ether.c | 8 +++++--- usr.sbin/arp/arp.4 | 11 +++++++++++ 2 files changed, 16 insertions(+), 3 deletions(-) diff --git a/sys/netinet/if_ether.c b/sys/netinet/if_ether.c index 8e2daebbe049..52d7db228dcf 100644 --- a/sys/netinet/if_ether.c +++ b/sys/netinet/if_ether.c @@ -496,6 +496,7 @@ arpintr(struct mbuf *m) static int log_arp_wrong_iface = 1; static int log_arp_movements = 1; static int log_arp_permanent_modify = 1; +static int allow_multicast = 0; SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_wrong_iface, CTLFLAG_RW, &log_arp_wrong_iface, 0, @@ -506,7 +507,8 @@ SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_movements, CTLFLAG_RW, SYSCTL_INT(_net_link_ether_inet, OID_AUTO, log_arp_permanent_modify, CTLFLAG_RW, &log_arp_permanent_modify, 0, "log arp replies from MACs different than the one in the permanent arp entry"); - +SYSCTL_INT(_net_link_ether_inet, OID_AUTO, allow_multicast, CTLFLAG_RW, + &allow_multicast, 0, "accept multicast addresses"); static void in_arpinput(struct mbuf *m) @@ -551,8 +553,8 @@ in_arpinput(struct mbuf *m) return; } - if (ETHER_IS_MULTICAST(ar_sha(ah))) { - log(LOG_NOTICE, "in_arp: %*D is multicast\n", + if (allow_multicast == 0 && ETHER_IS_MULTICAST(ar_sha(ah))) { + log(LOG_NOTICE, "arp: %*D is multicast\n", ifp->if_addrlen, (u_char *)ar_sha(ah), ":"); return; } diff --git a/usr.sbin/arp/arp.4 b/usr.sbin/arp/arp.4 index 980ca7194150..0ff0f2c279ad 100644 --- a/usr.sbin/arp/arp.4 +++ b/usr.sbin/arp/arp.4 @@ -120,6 +120,12 @@ of the .Xr sysctl 3 MIB. .Bl -tag -width "log_arp_permanent_modify" +.It Va allow_multicast +Should the kernel install ARP entries with multicast bit set in +the hardware address. +Installing such entries is RFC 1812 violation, but some prorietary +load balancing techniques require routers on network to do so. +Turned off by default. .It Va log_arp_movements Should the kernel log movements of IP addresses from one hardware address to an other. @@ -203,6 +209,11 @@ entry in the local ARP table. This error will only be logged if the sysctl .Va net.link.ether.inet.log_arp_permanent_modify is set to 1, which is the system's default behaviour. +.It "arp: %x:%x:%x:%x:%x:%x is multicast" +Kernel refused to install an entry with multicast hardware address. +If you really want such addresses being installed, set the sysctl +.Va net.link.ether.inet.allow_multicast +to a positive value. .El .Sh SEE ALSO .Xr inet 4 ,