From: PETER.T.WHITING@sprint.sprint.com Subject: R. Thomas's NFS question Sender: owner-bugtraq@fc.net Content-Length: 907 R. Thomas> hostA --> exports /usr/share to -access=hostB R. Thomas> hostB --> a linux box. re-exports /usr/share to everyone R. Thamas> hostC --> not implicitly trusted by hostA, mounts /usr/share R. Thomas> aside from any security concerns, this would certainly R. Thomas> thrash your nfsd's. does anyone have any experience R. Thomas> with this? i have only recently discovered this, and R. Thomas> have not had time to peruse it in depth. Not a problem. Host C gets to look at ***HostB's*** /usr/share - the one that has HostA's /usr/share mounted over it, not HostA's /usr/share. NFS gives you a single hop. In the above example HostA could then mount (if perms were granted) HostC's /usr/share and everything would work. pete Peter T. Whiting [snip] End of excerpt.... After reading the man page for nfsd on a Linux box, I have to agree with Mr. Thomas. The man page even makes reference to using this feature to function as a NFS multiplier, whatever that may be.... Anyway, the security concern raised by Mr. Thomas is valid. Mr. Whiting is correct in that most of the nfsd's I know about do not behave this way, and I belive Linux's can, by simply not specifing '-r' on the command line. I have not tried this, and I may be wrong, so it is worth a check yourself. Dave Dillow il1@ornl.gov dillow@cs.utk.edu