I have modified arp.c in order avoid responses to arp requests when the
source IP is equal that the target IP and Proxy-ARP is enabled.
This feature will support to hosts with static IP even when the address
are topologically incorrect.
With 'iptables rules', 'ip routes' and 'proxy_arp' it is posible to
connect a machine with 'incorrect IP' in our internal network and this
computer will use internet without problems.
This is usefull as a DHCP Fail-safe mechanism (windows assign an IP to
the interface when dhcpd is not contacted) or when a mobile client
without adm privilegies can't change his/her static IP.
Without this patch windows respond with an error message when proxy_arp
is enabled (The system has detected a conflict for IP .....).
Manolo
********************************* CUT ****************
--- linux.org/net/ipv4/arp.c Fri Sep 7 20:01:20 2001
+++ linux/net/ipv4/arp.c Wed Aug 21 15:44:14 2002
@@ -773,9 +773,9 @@
if (n)
neigh_release(n);
- if (skb->stamp.tv_sec == 0 ||
+ if ( sip != tip && (skb->stamp.tv_sec ==
0 ||
skb->pkt_type == PACKET_HOST ||
- in_dev->arp_parms->proxy_delay == 0) {
+ in_dev->arp_parms->proxy_delay == 0) ) {
arp_send(ARPOP_REPLY,ETH_P_ARP,sip,dev,tip,sha,dev->dev_addr,sha);
} else {
pneigh_enqueue(&arp_tbl,
in_dev->arp_parms, skb);
******************************* END CUT ***************
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