> It seems that one can't use proxy-arp for alias interfaces.
> Using it for the respective real interface works fine, and this
> is what I have been doing this far when I have needed to use
> proxy-arp "manually". But now I configured ppp-server and pppd
> finds an alias interface when it looks for a network interface
> on the same subnet as the host, tries to create ARP entry and
> Oct 11 13:25:48 xxxxxx pppd[yyyyy]: found interface eth0:0 for proxy arp
> Oct 11 13:25:48 xxxxxx pppd[yyyyy]: ioctl(SIOCSARP): Operation not supported by device(19)
> This is unfortunately a lot more problematic as I can't force
> pppd to use some hardwired interface (except by modifying the
> source). Which one actually is guilty, pppd or the kernel? Is
> this how kernel is intended to work? In case I'm missing
> something obvious, do inform me.
The fix is easy, just change pppd to not set the ATF_COM flag in the
SIOCSARP ioctl. If it is set the kernel thinks it contains a valid hardware
address, and if it can't find that address it will return ENODEV (as in
In 2.1 proxy arp entries are not associated with any device anymore, they
thus have no hardware address.
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