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Subject[PATCH] net: Add the same IP detection for duplicate address.
Date
The network sends an ARP REQUEST packet to determine
whether there is a host with the same IP.
Windows and some other hosts may send the source IP
address instead of 0.
When IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP) is enable,
the REQUEST will be dropped.
When IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP) is disable,
The case should be added to the IP conflict handling process.

Signed-off-by: Dongxu Liu <liudongxu3@huawei.com>
---
net/ipv4/arp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 05eb42f..a51c921 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -801,7 +801,7 @@ static int arp_process(struct net *net, struct sock *sk, struct sk_buff *skb)
GFP_ATOMIC);

/* Special case: IPv4 duplicate address detection packet (RFC2131) */
- if (sip == 0) {
+ if (sip == 0 || sip == tip) {
if (arp->ar_op == htons(ARPOP_REQUEST) &&
inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL &&
!arp_ignore(in_dev, sip, tip))
--
2.12.3

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