nmap as root ... not allowed?

[bell]

Hi,

whenever I try to run nmap as root, I get the following response:

Starting nmap 3.75 ( http://www.insecure.org/nmap/ ) at 2005-01-05 11:26 CET
Note: Host seems down. If it is really up, but blocking our ping probes, try -P0
Nmap run completed -- 1 IP address (0 hosts up) scanned in 0.115 seconds

I did some googling, and found the following thread:
http://www.linuxforum.com/forums/index.php?showtopic=72612&st=0&#entry318457

The last entry is interesting:

I had the simililar problem. SuSE is to blame: "Security Fix: nmap does not run as root due to bad interaction between kernel and user-space for pre calculated IP checksum. Thanks to Dirk Mueller for debugging." The fix is from 27-Jan-2004. Go and pull the fix from the SuSE site: ftp://ftp.suse.com/pub/suse/i386/update/9...m/i586/nmap.rpm

Is there a workaround for this problem in FC3 as well ??? (Or is there some other reason why nmap does not run as root for me? I've seen references from other fc-users who apparantly run nmap as root just fine...) As root, I am still able to ping the host I want to nmap. I am using nmap from the "Dag" repository.

[Jman]

Have you tried nmap and ping as a user? You can't use advanced nmap features but you can do a simple port scan.

[bell]

Oh, sorry, forgot to mention that :) Yes, I can use nmap as a regular user, but can't, as you mentioned, do the "more interesting" stuff... I have not discovered anything wrong with my box, other than that I can't use nmap as root... I also have an old box running fc1 with this exact same behaviour... (But this post mainly regards my fc3-box mentioned in the first post.)

All symptoms indicate that there is something done either with nmap or with the system to disallow root from running nmap. I can ping, traceroute, ftp, ssh etc. with both regular users and root. But nmap only works with regular users.