OpenSUSE -icmp_seq= Redirect Host

From 192.168.4.251: icmp_seq=2 Redirect Host(New nexthop: 192.168.4.1)

Source
You are seeing ICMP Redirects. Directly from Cisco, ICMP Redirects happen when:

- The interface on which the packet comes into the router is the same interface on which the packet gets routed out.
- The subnet or network of the source IP address is on the same subnet or network of the next-hop IP address of the routed packet.
- The datagram is not source-routed .
- The kernel is configured to send redirects.

You can disable ICMP redirects by going under interface config mode and issuing  
no ip redirects
and you won't see that anymore.
"Redirect Host" messages

If I understand this correctly, the 'hub' cannot talk anymore to 'the remote nodes' than the computer you were using for the ping. It just happens to have the necessary routing information to know the gateway IP-addresses for the 192.168.3/24 and 192.168.2/24 networks. I need to do a little guesswork here: 

I assume that your 'remote nodes' are actually located in these two networks and that you are not operating a really weird layer 2 device which physically partitions the ethernet connected to eth1 of the hub. If this is so, you could just put everything which is part of this LAN into a single IP-network, continue to use the 'hub' as default gateway and configure the other stations to simply make use of the information in the redirect messages. Alternatively, continuing to use the hub as 'gateway' should work as well, it will just cause a (probably non-relevant) slowdown.