After searching all over for what would seem to be a common issue, and failing to find the answer, I'm going to post the answer I've found here. It would seem that such a problem might deserve a FAQ entry or Stickyness.

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I've encountered this  problem with several (all?) of the ipkged NoCatSplashes
for OpenWRT White Russian RC3:

On a WRT54GS v1.0, in every case, splashd -D
yields:

'iptables: no target/chain/match by that name'

upon loading. This is apparently caused by the fact that the 'ipt_REDIRECT'
module is not loading.

To fix the issue, vim on into initialize.fw, and change line 32:

FROM:
for module in ipt_TOS ipt_mac; do

TO:
for module in ipt_REDIRECT ipt_TOS ipt_mac; do

And Voe Illa! NoCatSplash!

[I'm using Schuyler Erle's ipkg, available at
http://nocat.net/~sderle/nocatsplash_0. … mipsel.ipk
<http://nocat.net/%7Esderle/nocatsplash_ … mipsel.ipk>. I believe, however, this fix should handle any of the NoCatSplash+White Russian installs.]

Thanks for such a great tool, guys,

Chris

PS Should someone see an error in my ways, please yell at me at your
earliest convenience. I'll be putting this live in a busy coffeshop.
[Actually, if anyone has any experience or comments on NoCatSplash
performance under heavy load, please let me know.]

In fact, there seems to be interesting patches in the ewrt source. I have not yet repacked NoCatSplash, but it seems to be much more working.

The fix JustThisGuy describes worked for me as well.  Our hotspot only just opened, so can't speak to load issues for nocatsplash.

WRT54G v4 with RC3, using Schyler Earle's ipkg as above, with hacks as per oceanhippie.com to get nocatsplash to work.

I agree, the nocatsplash fix ought to be a sticky: damn useful tool, the nocatsplash, for community hotpot start-ups.