IP forwarding for 2.2.x kernels

[Debian project development discussion <debian-user@orbits.com>]

Is there some magic involved with IP forwarding for the 2.2.x kernels?

I have a box with a brand-new Debian installation (slink), a custom-
built 2.2.5 kernel, and a pair of ne2000 ethernet cards.  I can ping
systems going out through both cards, so I know they are both working.
I just cannot get packets to route _through_ the system.  I have done
the arcane bit of magic mentioned in the kernel help file:
  echo "1" > /proc/sys/net/ipv4/ip_forward
  echo "0" > /proc/sys/net/ipv4/conf/eth0
  echo "0" > /proc/sys/net/ipv4/conf/eth1

The routing appears to be correct.  I have specified routes to networks
through each of the ethernet cards and a default route to one of the
hosts on one of the networks.

Networking part of the kernel .config:
  #
  # Networking options
  #
  CONFIG_PACKET=y
  CONFIG_NETLINK=y
  CONFIG_RTNETLINK=y
  # CONFIG_NETLINK_DEV is not set
  CONFIG_FIREWALL=y
  # CONFIG_FILTER is not set
  CONFIG_UNIX=y
  CONFIG_INET=y
  # CONFIG_IP_MULTICAST is not set
  CONFIG_IP_ADVANCED_ROUTER=y
  CONFIG_RTNETLINK=y
  CONFIG_NETLINK=y
  # CONFIG_IP_MULTIPLE_TABLES is not set
  # CONFIG_IP_ROUTE_MULTIPATH is not set
  # CONFIG_IP_ROUTE_TOS is not set
  # CONFIG_IP_ROUTE_VERBOSE is not set
  # CONFIG_IP_ROUTE_LARGE_TABLES is not set
  # CONFIG_IP_PNP is not set
  CONFIG_IP_FIREWALL=y
  # CONFIG_IP_FIREWALL_NETLINK is not set
  CONFIG_IP_ALWAYS_DEFRAG=y
  # CONFIG_IP_TRANSPARENT_PROXY is not set
  # CONFIG_IP_MASQUERADE is not set
  CONFIG_IP_ROUTER=y
  # CONFIG_NET_IPIP is not set
  # CONFIG_NET_IPGRE is not set
  CONFIG_IP_ALIAS=y
  # CONFIG_SYN_COOKIES is not set

(Note that I have aliased eth1, to that there are two virtual networks
on that physical network, but I don't think that should affect this.)

I have a system with 2.0.35, through which packets route just fine, so I
don't think I'm totally lost.  I suspect I either mis-set something when
I built the kernel, or there is some new configuration that I don't know
about.  Someone please enlighten me.

Thanks,
David H. Silber

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