PPP and ProxyARP

PPP and ProxyARP

Post by ND Holme » Fri, 31 Jul 1998 04:00:00



I'm having a problem and, after spending hours searching the web and
trying various ideas I've had, I've still had no success.  I have a
linux box connected to the university ethernet here, which also has a
radio modem attached to one of its serial ports.  I've been trying to
set this modem up such that I can haul the laptop around without being
cabled down to anything.  Simple enough, right, since they both have
real IP numbers assigned to them?  Ethernet interface on one side, PPP
with the proxyarp option on the other, and everything supposedly works.
However, I can get the PPP link established and working (I can telnet
from the laptop to the linux box), and the linux box can see the rest of
the net through the ethernet interface, but packets are not making it
between the interfaces.

I've set up systems like this before, and have never had any problems
until this time.  But no matter what I try or how many times I check my
work, I can't get proxyarp to work in this case.

The linux server is named larry.eng.iastate.edu (129.186.4.149), and is
a P-120 with a fairly straightforward RedHat 5.0 distribution with a
2.0.35 kernel (which, yes, has forwarding/gatewaying turned on).  The
laptop is a W95 box named excytor (129.186.4.128).

The system is straightfoward, laid out like this:

<ENET BACKBONE> --------- (eth0) [larry.eng.iastate.edu]
(ppp0)---------(ppp)[excytor.eng.iastate.edu]

If anyone has any idea why this system might not work, could you please
email me?  It would be greatly appreciated if anyone could help me out.

Nathan D. Holmes

For assistance, here are a few critical things about the system:

pppd startup command:

/usr/sbin/pppd /dev/cua0 19200 crtscts proxyarp persist mru 576 mtu 576
129.186.4.149:129.186.4.128

ifconfig:

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Bcast:127.255.255.255  Mask:255.0.0.0
          UP BROADCAST LOOPBACK RUNNING  MTU:3584  Metric:1
          RX packets:808 errors:0 dropped:0 overruns:0
          TX packets:808 errors:0 dropped:0 overruns:0

eth0      Link encap:Ethernet  HWaddr 00:AA:00:62:59:B1
          inet addr:129.186.4.149  Bcast:129.186.4.255
Mask:255.255.254.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:18764 errors:0 dropped:0 overruns:0
          TX packets:1871 errors:0 dropped:0 overruns:0
          Interrupt:10 Base address:0x300

ppp0      Link encap:Point-to-Point Protocol
          inet addr:129.186.4.149  P-t-P:129.186.4.128
Mask:255.255.255.0
          UP POINTOPOINT RUNNING  MTU:576  Metric:1
          RX packets:10 errors:0 dropped:0 overruns:0
          TX packets:11 errors:0 dropped:0 overruns:0

route:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use
Iface
excytor.eng.ia *               255.255.255.255 UH    0      0        1
ppp0
129.186.4.0     *               255.255.255.0   U     0      0       11
eth0
127.0.0.0       *               255.0.0.0       U     0      0        4
lo
default         router4.iastate 0.0.0.0         UG    0      0       10
eth0

arp:
Address                 HWtype  HWaddress           Flags
Mask            Iface
mulder.eng.iastate.edu         ether   00:80:48:A9:FC:A4
C                     eth0
129.186.4.254                   ether   00:10:11:AD:C8:80
C                     eth0
phoenix.eng.iastate.edu       ether   00:00:C0:DE:30:D8
C                     eth0
excytor.eng.iastate.edu        ether   00:AA:00:62:59:B1
CMP                   eth0

 
 
 

PPP and ProxyARP

Post by Kalevi Hautanie » Sat, 01 Aug 1998 04:00:00


: I'm having a problem and, after spending hours searching the web and
: trying various ideas I've had, I've still had no success.  I have a
: linux box connected to the university ethernet here, which also has a
: radio modem attached to one of its serial ports.  I've been trying to
: set this modem up such that I can haul the laptop around without being
: cabled down to anything.  Simple enough, right, since they both have
: real IP numbers assigned to them?  Ethernet interface on one side, PPP
: with the proxyarp option on the other, and everything supposedly works.
: However, I can get the PPP link established and working (I can telnet
: from the laptop to the linux box), and the linux box can see the rest of
: the net through the ethernet interface, but packets are not making it
: between the interfaces.

: I've set up systems like this before, and have never had any problems
: until this time.  But no matter what I try or how many times I check my
: work, I can't get proxyarp to work in this case.

: The linux server is named larry.eng.iastate.edu (129.186.4.149), and is
: a P-120 with a fairly straightforward RedHat 5.0 distribution with a
: 2.0.35 kernel (which, yes, has forwarding/gatewaying turned on).  The
: laptop is a W95 box named excytor (129.186.4.128).

Has that winbox a box 'use default gateway on remote network' checked?
Have you it's DNS set up correctly?

: ppp0      Link encap:Point-to-Point Protocol
:           inet addr:129.186.4.149  P-t-P:129.186.4.128
: Mask:255.255.255.0
:           UP POINTOPOINT RUNNING  MTU:576  Metric:1
:           RX packets:10 errors:0 dropped:0 overruns:0
:           TX packets:11 errors:0 dropped:0 overruns:0

Really strange value for MTU. Is there a reason to that 576?

--
Kalevi J Hautaniemi,      Marjatankatu 12,     33730 Tampere,  FINLAND.
****  http://oh3tr.ele.tut.fi/~oh3fg/ ****  On air:  OH3FG, KO4BC  ****
tel:+358-3-364-7446    fax:+358-3-364-2476    mobile:+358-50-590-2243

 
 
 

PPP and ProxyARP

Post by Hyunsoo Mi » Thu, 06 Aug 1998 04:00:00



> I'm having a problem and, after spending hours searching the web and
> trying various ideas I've had, I've still had no success.  I have a
> linux box connected to the university ethernet here, which also has a
> radio modem attached to one of its serial ports.  I've been trying to
> set this modem up such that I can haul the laptop around without being
> cabled down to anything.  Simple enough, right, since they both have
> real IP numbers assigned to them?  Ethernet interface on one side, PPP
> with the proxyarp option on the other, and everything supposedly works.
> However, I can get the PPP link established and working (I can telnet
> from the laptop to the linux box), and the linux box can see the rest of
> the net through the ethernet interface, but packets are not making it
> between the interfaces.

> I've set up systems like this before, and have never had any problems
> until this time.  But no matter what I try or how many times I check my
> work, I can't get proxyarp to work in this case.

> The linux server is named larry.eng.iastate.edu (129.186.4.149), and is
> a P-120 with a fairly straightforward RedHat 5.0 distribution with a
> 2.0.35 kernel (which, yes, has forwarding/gatewaying turned on).  The
> laptop is a W95 box named excytor (129.186.4.128).

> The system is straightfoward, laid out like this:

> <ENET BACKBONE> --------- (eth0) [larry.eng.iastate.edu]
> (ppp0)---------(ppp)[excytor.eng.iastate.edu]

> If anyone has any idea why this system might not work, could you please
> email me?  It would be greatly appreciated if anyone could help me out.

> Nathan D. Holmes

> For assistance, here are a few critical things about the system:

> pppd startup command:

> /usr/sbin/pppd /dev/cua0 19200 crtscts proxyarp persist mru 576 mtu 576
> 129.186.4.149:129.186.4.128

> ifconfig:

> lo        Link encap:Local Loopback
>           inet addr:127.0.0.1  Bcast:127.255.255.255  Mask:255.0.0.0
>           UP BROADCAST LOOPBACK RUNNING  MTU:3584  Metric:1
>           RX packets:808 errors:0 dropped:0 overruns:0
>           TX packets:808 errors:0 dropped:0 overruns:0

> eth0      Link encap:Ethernet  HWaddr 00:AA:00:62:59:B1
>           inet addr:129.186.4.149  Bcast:129.186.4.255
> Mask:255.255.254.0
>           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
>           RX packets:18764 errors:0 dropped:0 overruns:0
>           TX packets:1871 errors:0 dropped:0 overruns:0
>           Interrupt:10 Base address:0x300

> ppp0      Link encap:Point-to-Point Protocol
>           inet addr:129.186.4.149  P-t-P:129.186.4.128
> Mask:255.255.255.0
>           UP POINTOPOINT RUNNING  MTU:576  Metric:1
>           RX packets:10 errors:0 dropped:0 overruns:0
>           TX packets:11 errors:0 dropped:0 overruns:0

> route:

> Kernel IP routing table
> Destination     Gateway         Genmask         Flags Metric Ref    Use
> Iface
> excytor.eng.ia *               255.255.255.255 UH    0      0        1
> ppp0
> 129.186.4.0     *               255.255.255.0   U     0      0       11
> eth0
> 127.0.0.0       *               255.0.0.0       U     0      0        4
> lo
> default         router4.iastate 0.0.0.0         UG    0      0       10
> eth0

> arp:
> Address                 HWtype  HWaddress           Flags
> Mask            Iface
> mulder.eng.iastate.edu         ether   00:80:48:A9:FC:A4
> C                     eth0
> 129.186.4.254                   ether   00:10:11:AD:C8:80
> C                     eth0
> phoenix.eng.iastate.edu       ether   00:00:C0:DE:30:D8
> C                     eth0
> excytor.eng.iastate.edu        ether   00:AA:00:62:59:B1
> CMP                   eth0

  If your host system is RedHat , check whether the file
/etc/sysconfig/network  contains the line
"FORWARD_IPV4=yes".   Of course your kernel should support IP_FORWARDING.
 
 
 

1. How to configure proxyarp with FreeBSD's user-mode PPP

Hi - can anyone help me?

I'm re-building my FreeBSD system around 2.1.5.  I've got the user-mode PPP
(the one
using the tunnel device) running properly in auto mode, but one thing still
eludes me.  

The documentation says that it supports proxy ARP, but I just can't see how
to
configure that.  None of the documentation says how to do it, and none of
the examples
seem to have it.  Nor do any of the  "obvious" commands (like proxy,
proxyarp, set
proxyarp) seem to work.  I'm mystified!

Can anyone shed some light on this for me?

I know how to make it work with the alternate kernel-mode PPP, but I'd
prefer to stick with the user-mode PPP if possible.

Nick.

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