[Beowulf] automount on high ports

Perry E. Metzger perry at piermont.com
Tue Jul 1 13:21:55 PDT 2008

Henning Fehrmann <henning.fehrmann at aei.mpg.de> writes:
>> Thus, your problem sounds rather odd. There is no obvious reason you
>> should be limited to 360 connections.
>> Perhaps your problem is not what you think it is at all. Could you
>> explain it in more detail?
> I guess it has also something to do with the automounter. I am not able
> to increase this number. 
> But even if the automounter would handle more we need to be able to 
> use higher ports: 
> netstat shows always ports below 1024.
> tcp        0      0 client:941         server:nfs
> We need to mount up to 1400 nfs exports.

All NFS clients are connecting to a single port, not to a different
port for every NFS export. You do not need 1400 listening TCP ports on
a server to export 1400 different file systems. Only one port is
needed, whether you are exporting one file system or one million, just
as only one SMTP port is needed whether you are receiving mail from
one client or from one million.

The clients are connecting from ports below 1024 because Berkeley set
up a hack in the original BSD stack so that only root could open ports
below 1024. This way, you could "know" the process on the remote host
was a root process, thus you could feel "secure" [sic]. It doesn't add
any real security any more, but it is also not the cause of any
problem you are experiencing.

We can help you figure this out, but you will have to give a lot more
detail about the problem. Please describe your network setup. How many
servers do you have? How many clients? How many file systems are those
servers exporting? How many is a typical client mounting, and why?
Start there and we can try to move forward.

Perry E. Metzger		perry at piermont.com

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