I have worked on the back port of the fixes for tcpdump on RH 7.3, It was not so easy. I had to skip "_U_" on the following lines 418 471 554 617 635 778 804 830 848 866 885 1017 1055 in the print-isakmp.c file in order to get it to compile.
I don't know if this have any impact on the security you can compare with the original patch that is in RH 9 update, the patch name is: "tcpdump-3.7.2-CAN-2003-0989.patch".
Perhaps someone knows this better than me, but anyway it should be much better now :)
Anyway the rpms are ready and they seems to work ok, you can get them from here:
http://av8.netikka.fi/~johnny/fedora_legacy/rh73/
Thanks!
Johnny