Compilation at a glibc2.1/kernel 2.2 system fails at 2 locations. 1. netconf/ipx.cc _needs_ an explicit "#include <sys/socket.h>" (else you get a lot of missing symbols). Currently this file will be included only if there is no GLIBC. I guess this is done because the old libc5 had problems to include some network headers together. 2. the firewall module has no chance to compile at a glibc2.1 system. The FAQ of this library says: "3.16. Why has <netinet/ip_fw.h> disappeared? {AJ} The corresponding Linux kernel data structures and constants are totally different in Linux 2.0 and Linux 2.2. This situation has to be taken care in user programs using the firewall structures and therefore those programs (ipfw is AFAIK the only one) should deal with this problem themselves." So I think the best solution is to remove the firewall directory from the DIRS-entry in modules/Makefile. I know there is a new linuxconf 1.13 out there but I don't know if it has still the errors above.
Fixed in the current beta