This is with -current 4.1.6 ipfilter.. It looks as though I have something
back to front..

tcpdump:

IP cowsadmin.204.168.192.in-addr.arpa.1164 > 192.168.205.130.http: S 4208745430:4208745430(0) win 65535 <mss 1460,nop,nop,sackOK>
IP gw.168.192.in-addr.arpa > cowsadmin.admin.newn.cam.ac.uk.204.168.192.in-addr.arpa: icmp 36: redirect 192.168.205.130 to host 192.168.205.130

note the redirect .205.130 to .205.130 (ie no change) yet this is a tcpdump
on interface vlan3, on which the following nat rule should apply:

rdr vlan3 192.168.205.130/32 port 80 -> 192.168.0.130 port 80 tcp

Am I missing something?

Cheers,

Patrick