18 Jan
2018
18 Jan
'18
10 a.m.
On Thu, Jan 18, 2018 at 10:39 AM, Grant Taylor via cctalk <
cctalk at classiccmp.org> wrote:
I was not aware that there was code that supported
/only/ Class A (/8)
addresses and /not/ Class B (/16) or Class C (/24) addresses.
I /thought/ that everything was either classful (as in supports all three
classes: A, B, and C) or classless (as in supports CIDR).
Years ago I added a configurable "bozo-arp" feature to the Telebit
NetBlazer router, which would respond to ARP requests for non-local
addresses and reply with the router's MAC address (on that interface),
specifically in order to make classful-only hosts work on a CIDR network.
Later someone paid me to write a NetBSD daemon ("anyipd") to do the same
thing, though for an entirely different reason. Recently I've needed that
functionality on Linux, as I have multiple old systems that only understand
classful, including the AT&T UnixPC (7300 or 3B1). I suppose I should
rewrite and open-source it.
18 Jan
18 Jan
10:35 a.m.
On 01/18/2018 11:00 AM, Eric Smith wrote:
Years ago I added a configurable "bozo-arp"
feature to the Telebit
NetBlazer router, which would respond to ARP requests for non-local
addresses and reply with the router's MAC address (on that interface),
specifically in order to make classful-only hosts work on a CIDR
network.
That functionality sounds exactly like my understanding of what Proxy
ARP is supposed to do.
Later someone paid me to write a NetBSD daemon
("anyipd") to do the same
thing, though for an entirely different reason.
Nice.
Since you stated that anyipd "?would respond to ARP requests for
non-local addresses?" I"m assuming that you are talking IP and not
another protocol. Please correct me if I'm assuming incorrectly.
Recently I've needed that functionality on Linux,
as I have multiple
old systems that only understand classful, including the AT&T UnixPC
(7300 or 3B1). I suppose I should rewrite and open-source it.
I'm trying to make sure that I understand what you're wanting / needing
to do and evaluate if Proxy ARP can do it or not.
I'm guessing that you have a host, AT&T Unix PC, that's at (for the sake
of discussion) 10.20.30.40/8 and you'd like to communicate with another
machine that's at 10.10.10.10/24. Obviously 10.10.10.10/24 is a subset
of 10.0.0.0/8, so the AT&T Unix PC thinks that 10.10.10.10 is local. -
Does this accurately represent your use case?
Unless you correct me, I'm going to assume that this is accurate enough
for the sake of discussion.
I /think/ (it's been too long since I've done this) that you would
configure one classless interface with 10.20.30.254/24 and another
classless interface with 10.10.10.254/24 -and- enable Proxy ARP on both
(?) interfaces. You will likely need to enter the target machine's IP
addresses in a file that the Proxy ARP sub-system references to learn
what target IPs that it needs to Proxy ARP for.
I might not have the nuances exactly correct because I've not done this
in a long time. But I have made this scenario work with the Proxy ARP
support that currently exists in the Linux kernel.
So ? I wonder what additional functionality your anyipd would provide.
- I'm actually quite curious to learn.
--
Grant. . . .
unix || die
11:53 a.m.
On Thu, Jan 18, 2018 at 11:35 AM, Grant Taylor via cctalk <
cctalk at classiccmp.org> wrote:
On 01/18/2018 11:00 AM, Eric Smith wrote:
Proxy ARP is (or was, at the time) something that had to be configured for
individual IP addresses or ranges. What I did was have it reply to an ARP
for _any_ IP address outside the subnet(s) configured on that interface.
Since you stated that anyipd "?would respond to ARP requests for non-local
Years ago I added a configurable
"bozo-arp" feature to the Telebit
NetBlazer router, which would respond to ARP requests for non-local
addresses and reply with the router's MAC address (on that interface),
specifically in order to make classful-only hosts work on a CIDR network.
That functionality sounds exactly like my understanding of what Proxy ARP
is supposed to do.
addresses?" I"m assuming that you are
talking IP and not another protocol.
Yes. Specifically IPv4.
Recently I've needed that functionality on Linux, as I have multiple old
systems that
only understand classful, including the AT&T UnixPC (7300 or
3B1). I suppose I should rewrite and open-source it.
I /think/ (it's been too long since I've done
this) that you would
configure one classless interface with 10.20.30.254/24 and another
classless interface with 10.10.10.254/24 -and- enable Proxy ARP on both
(?) interfaces. You will likely need to enter the target machine's IP
addresses in a file that the Proxy ARP sub-system references to learn what
target IPs that it needs to Proxy ARP for.
The point of bozo-arp and anyipd was that the only necessary configuration
was to turn it on. Of course, there may be scenarios in which one does not
want the router to respond to bogus ARP requests, in which case
bozo-arp/anyipd should not be used.
1:12 p.m.
On 01/18/2018 12:53 PM, Eric Smith via cctalk wrote:
Proxy ARP is (or was, at the time) something that had
to be configured
for individual IP addresses or ranges. What I did was have it reply to an
ARP for any IP address outside the subnet(s) configured on that interface.
Intriguing.
I guess this means that you only heard ARP requests for IP addresses
that other systems in the same broadcast domain thought were local to
said broadcast domain.
You wouldn't need to worry about errant ARP requests for things outside
of the local subnet as that would go through the default gateway (or
other defined router).
I like it.
Yes. Specifically IPv4.
*nod*
The point of bozo-arp and anyipd was that the only
necessary configuration
was to turn it on. Of course, there may be scenarios in which one does
not want the router to respond to bogus ARP requests, in which case
bozo-arp/anyipd should not be used.
Like all tools, you have to be careful where you do use it. - I'd
default with it off (or not installed) and turn it on as necessary.
--
Grant. . . .
unix || die
2530
days inactive
2530
days old
3 comments
2 participants
participants (2)
-
cctalk＠gtaylor.tnetconsulting.net -
spacewar＠gmail.com