查了一下，终于知道IPFILTER，我还以为是个软件包了，只是个命令么（惭愧，以前从不知道有这个命令，IPTRACE和IPREPORT到用过
）。根据以下解释：
Extracts different operation headers from an ipreport output file and displays them in a table. Some customized nfs information regarding requests and replies is also provided.
u n t x c a Specifies operation headers (udp, nfs, tcp, ipx, and icmp and atm respectively).
-d milliseconds Only Call/Reply pairs whose elapsed time is greater than milliseconds are to be shown.
-f [ u n t x c a ] Selected operations are to be shown in ipfilter.all.
-n Generates an nfs.rpt.
-s [ u n t x c ] Separate files are to be produced for each of the selected operations.
他只是个检查工具，跟NAT和代理有关系么？
