i set arp proxy on one 2.6.15kernel fedora5 linux.
[root@localhost devices]# arp -i eth0 -s 192.168.1.150 00:0C:29:BF:A3:72 pub
[root@localhost devices]# tcpdump arp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
14:22:59.594979 arp who-has 192.168.1.150 tell 192.168.1.100
14:23:04.909410 arp who-has 192.168.1.150 tell 192.168.1.100
14:23:10.202343 arp who-has 192.168.1.150 tell 192.168.1.100
14:23:15.704404 arp who-has 192.168.1.150 tell 192.168.1.100

the proxy_arp variable under the /proc/... are set to 1

anyone knows why does it not work?

Give more detail, I don't see any problem here..

i set proxy arp on host A
[root@localhost devices]# arp -i eth0 -s 192.168.1.150 00:0C:29:BF:A3:72 pub

so i expect host A to answer arp request for address 192.168.1.150

then on host B i ping 192.168.1.150, host B send some arp request for 192.168.1.150,

but host A doesnot answer that arp request.

should it work at all? or my understanding of proxy arp is wrong?