Messages in this thread | | | Date | Tue, 10 Nov 2009 15:06:25 -0600 | From | "Chris Friesen" <> | Subject | Re: sunrpc port allocation and IANA reserved list |
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On 11/10/2009 02:26 PM, Trond Myklebust wrote: > On Tue, 2009-11-10 at 12:37 -0600, Chris Friesen wrote: >> On 11/10/2009 11:53 AM, Ben Hutchings wrote: >>> On Tue, 2009-11-10 at 11:43 -0600, Chris Friesen wrote: >> >>>> Given that a userspace application can be stopped and restarted at any >>>> time, and a sunrpc registration can happen at any time, what is the >>>> expected mechanism to prevent the kernel from allocating a port for use >>>> by sunrpc that reserved or well-known? >>>> >>>> Apparently Redhat and Debian have distro-specific ways of dealing with >>>> this, but is there a standard solution? Should there be? >>>> >>>> The current setup seems suboptimal. >>> >>> I believe both RH and Debian are using the same implementation: >>> <http://cyberelk.net/tim/software/portreserve/>. >> >> That helps with the startup case, but still leaves a possible hole if an >> app using a fixed port number is restarted at runtime. During the >> window where nobody is bound to the port, the kernel could randomly >> assign it to someone else. > > Just use /proc/sys/sunrpc/{max,min}_resvport interface to restrict the > range used to a safer one. That's what it is for...
What constitutes a "safer range"? IANA has ports assigned intermittently all the way through the default RPC range. The largest unassigned range is 922-988 (since 921 is used by lwresd). If someone needs more than 66 ports, how are they supposed to handle it?
Chris
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