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Subject[PATCH] proxyarp for shaper device, kernel 2.4.9
I report here a tested and working patch to manage proxy arp on shaper device.
Details are on readme.txt file attached.
I had problems using only a patch file, if someone could tell me what is the
right command to make a diff file for all kernel source tree.... (I tried
with "diff -ur tree.orig tree.modified > diff_file" but also other useless
data are reported... :-()
Thank you
Best Regards
Roberto ArcomanoSubject: PATCH to update proxy arp feature on shaper device

Author: Roberto Arcomano,,

Date: 9/9/2001

Description: Shaper device is seen by the kernel like a
different device (i.e. shaper0) than the
physical one (i.e. eth0) to which is attached:
so kernel always issues an "ARP REPLY"
(if proxy arp is active on shaper physical
interface): this prevent us from use proxy arp on
a shaper device cause, during turning on client
machine, we would receive an "IP conflit" message.

Solution: Patch consists in 4 files:
a-) "include/linux/netdevice.h", where we add a new
net feature, NETIF_F_SHAPER which will help
us to understand if a device is a shaper one.

b-) "drivers/net/shaper.c", in "shaper_probe" function
we set NETIF_F_SHAPER flag for a new shaper

c-) "include/linux/if_shaper.h" where we add the macro
IS_SHAPERDEVICE, used to know if the device is a
shaper one (it checks NETIF_F_SHAPER flag in
features field, under "netdevice" struct).

d-) "net/ipv4/arp.c" where finally we modify proxy arp;
We use shflag to determine if we are managing a
shaper device (with IS_SHAPERDEVICE macro): in
this case we check
"rt->>priv->dev" (physical device)
instead of
"rt->" (shaper device)
while if the device is a non shaper one, we check
rt-> (anded with !shflag)

TODO: I used "features" field in netdevice struct: maybe it could
be choosen another place where to put the shaper flag.

Tests: I tested new feature using 3 PCs like that:

CLIENT1 ------------- LINUX ------------- CLIENT2
shaper0 ppp0

LINUX host has proxy arp and shaper enabled, with CLIENT1
reachable via shaper0.
With classic proxy arp, when I turn on CLIENT machine I
receive an "IP conflit" from OS, while using patched version
there are no problems.
Proxy arp still does its work cause, if I give CLIENT2 IP
address to CLIENT1 machine, I receive (from CLIENT1 OS) a
IP busy message.

Also tests on commercial server have been done with good

Kernel version tested is 2.4.9

Final notes: It should be very simple to port patch to older
kernel version (2.0.xx, 2.1.xx, 2.2.xx, 2.3.xx)

--- linux-2.4.9.orig/drivers/net/shaper.c Thu Jun 28 02:10:55 2001
+++ linux-2.4.9/drivers/net/shaper.c Sun Sep 9 16:27:17 2001
@@ -670,6 +670,7 @@
dev->addr_len = 0;
dev->tx_queue_len = 10;
dev->flags = 0;
+ dev->features |= NETIF_F_SHAPER;

* Shaper is ok--- linux-2.4.9.orig/include/linux/netdevice.h Sun Sep 9 16:15:40 2001
+++ linux-2.4.9/include/linux/netdevice.h Sun Sep 9 16:28:56 2001
@@ -345,6 +345,7 @@
#define NETIF_F_DYNALLOC 16 /* Self-dectructable device. */
#define NETIF_F_HIGHDMA 32 /* Can DMA to high memory. */
#define NETIF_F_FRAGLIST 64 /* Scatter/gather IO. */
+#define NETIF_F_SHAPER 128 /* Shaper device. */

/* Called after device is detached from network. */
void (*uninit)(struct net_device *dev);--- linux-2.4.9.orig/include/linux/if_shaper.h Wed Aug 18 20:38:47 1999
+++ linux-2.4.9/include/linux/if_shaper.h Sun Sep 9 16:27:01 2001
@@ -14,6 +14,8 @@
#define SHAPER_BURST (HZ/50) /* Good for >128K then */

+#define IS_SHAPERDEVICE(dev) ((dev)->features & NETIF_F_SHAPER)
struct shaper
struct sk_buff_head sendq;--- linux-2.4.9.orig/net/ipv4/arp.c Wed May 16 19:21:45 2001
+++ linux-2.4.9/net/ipv4/arp.c Sun Sep 9 16:26:55 2001
@@ -111,8 +111,7 @@

#include <asm/system.h>
#include <asm/uaccess.h>
+#include <linux/if_shaper.h>

* Interface to generic neighbour cache.
@@ -767,8 +766,15 @@
goto out;
} else if (IN_DEV_FORWARD(in_dev)) {
+ char shflag=0;
+ if ( (rt-> &&
+ (rt->>priv) &&
+ (((struct shaper *) rt->>priv)->dev) &&
+ shflag=1;
if ((rt->rt_flags&RTCF_DNAT) ||
- (addr_type == RTN_UNICAST && rt-> != dev &&
+ (addr_type == RTN_UNICAST &&
+ ( ((shflag) && ( ((struct shaper *) rt->>priv)->dev != dev)) || ((!shflag) && (rt-> != dev)) ) &&
(IN_DEV_PROXY_ARP(in_dev) || pneigh_lookup(&arp_tbl, &tip, dev, 0)))) {
n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
if (n)
 \ /
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