Proxy-Arp

[Shaun_O'Meara_(_at_)_graysecurity_(_dot_)_com]

Hi All

I have seen reference to questions concerning proxyarp before, but I have
been unable to find any real information pertaining to issues with it.

The problem that I am having concerns an OpenBSD 3.1 on an I386 box, using
PPTP and PPP with proxy arp enabled when a client connects I see
the entry for the proxy arp when I do an 'arp -a'. The problem occurs when
a machine on the network does a arp query the box does not reply.
I have confirmed that the machine is seeing the arp query by running
tcpdump on the interface in question.

Any pointers as to the problem would be of great help, below is the dmesg
output from the machine.


OpenBSD 3.1 (GENERIC) #0: Tue Nov 12 16:34:34 SAST 2002
    root_(_at_)_build:/usr/src/sys/arch/i386/compile/GENERIC
cpu0: Intel Pentium II (Klamath) ("GenuineIntel" 686-class, 512KB L2 cache)
266 MHz
cpu0: FPU,V86,DE,PSE,TSC,MSR,PAE,MCE,CX8,SYS,MTRR,PGE,MCA,CMOV,MMX
real mem  = 66695168 (65132K)
avail mem = 56291328 (54972K)
using 839 buffers containing 3436544 bytes (3356K) of memory
mainbus0 (root)
bios0 at mainbus0: AT/286+(20) BIOS, date 04/27/98, BIOS32 rev. 0 @ 0xec700
pcibios0 at bios0: rev. 2.1 @ 0xec700/0x3900
pcibios0: PCI IRQ Routing Table rev. 1.0 @ 0xf6f50/112 (5 entries)
pcibios0: PCI Interrupt Router at 000:20:0 ("Intel 82371AB PIIX4 ISA" rev
0x00)
pcibios0: PCI bus #1 is the last bus
bios0: ROM list: 0xc0000/0x8000 0xe0000/0x8000!
pci0 at mainbus0 bus 0: configuration mode 1 (no bios)
pchb0 at pci0 dev 0 function 0 "Intel 82443LX PCI-AGP" rev 0x03
ppb0 at pci0 dev 1 function 0 "Intel 82443LX AGP" rev 0x03
pci1 at ppb0 bus 1
vga1 at pci1 dev 0 function 0 "ATI Mach64 GZ" rev 0x3a
wsdisplay0 at vga1: console (80x25, vt100 emulation)
wsdisplay0: screen 1-5 added (80x25, vt100 emulation)
xl0 at pci0 dev 13 function 0 "3Com 3c905B 100Base-TX" rev 0x24: irq 11
address 00:a0:24:ab:39:bc
exphy0 at xl0 phy 24: 3Com internal media interface
xl1 at pci0 dev 14 function 0 "3Com 3c905B 100Base-TX" rev 0x24: irq 11
address 00:a0:24:ab:39:e2
exphy1 at xl1 phy 24: 3Com internal media interface
pcib0 at pci0 dev 20 function 0 "Intel 82371AB PIIX4 ISA" rev 0x02
pciide0 at pci0 dev 20 function 1 "Intel 82371AB IDE" rev 0x01: DMA,
channel 0 wired to compatibility, channel 1 wired to compatibility
wd0 at pciide0 channel 0 drive 0: <ST34311A>
wd0: 16-sector PIO, LBA, 4126MB, 8944 cyl, 15 head, 63 sec, 8452080 sectors
atapiscsi0 at pciide0 channel 0 drive 1
scsibus0 at atapiscsi0: 2 targets
cd0 at scsibus0 targ 0 lun 0: <SAMSUNG, CD-ROM SCR-2432, S100> SCSI0
5/cdrom removable
wd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 2
cd0(pciide0:0:1): using PIO mode 4, DMA mode 2
uhci0 at pci0 dev 20 function 2 "Intel 82371AB USB" rev 0x01: irq 11
usb0 at uhci0: USB revision 1.0
uhub0 at usb0
uhub0: vendor 0x0000 UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub0: 2 ports with 2 removable, self powered
"Intel 82371AB Power Mgmt" rev 0x02 at pci0 dev 20 function 3 not
configured
isa0 at pcib0
isadma0 at isa0
pckbc0 at isa0 port 0x60/5
pckbd0 at pckbc0 (kbd slot)
pckbc0: using irq 1 for kbd slot
wskbd0 at pckbd0: console keyboard, using wsdisplay0
pmsi0 at pckbc0 (aux slot)
pckbc0: using irq 12 for aux slot
wsmouse0 at pmsi0 mux 0
pcppi0 at isa0 port 0x61
midi0 at pcppi0: <PC speaker>
sysbeep0 at pcppi0
lpt0 at isa0 port 0x378/4 irq 7
npx0 at isa0 port 0xf0/16: using exception 16
pccom0 at isa0 port 0x3f8/8 irq 4: ns16550a, 16 byte fifo
pccom1 at isa0 port 0x2f8/8 irq 3: ns16550a, 16 byte fifo
fdc0 at isa0 port 0x3f0/6 irq 6 drq 2
fd0 at fdc0 drive 0: 1.44MB 80 cyl, 2 head, 18 sec
biomask 4840 netmask 4840 ttymask 58c2
pctr: 686-class user-level performance counters enabled
mtrr: Pentium Pro MTRR support
dkcsum: wd0 matched BIOS disk 80
root on wd0a
rootdev=0x0 rrootdev=0x300 rawdev=0x302

Thanks
Shaun