** Changed in: rpcbind (Debian)
Status: Unknown => Fix Released
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https://bugs.launchpad.net/bugs/304393
Title:
rpcbind grabs ports used by other daemons such as cupsd
Status in cups package in Ubuntu:
Invalid
Status in rpcbind package in Ubuntu:
Fix Released
Status in rpcbind source package in Xenial:
In Progress
Status in rpcbind source package in Bionic:
In Progress
Status in rpcbind package in Debian:
Fix Released
Status in Fedora:
Confirmed
Bug description:
[impact]
rpcbind binds to a 'random' reserved port at startup, which can
conflict with the reserved port number for other applications that
actually 'own' the reserved port number. One example is cups, which
uses the reserved port 631.
This prevents the actual 'owner' of the reserved port from starting,
since it can't bind to its reserved port.
Additionally, this can raise alarms from security monitoring software
that does not expect programs to be listening on random reserved
ports.
[test case]
start rpcbind and check which ports it is listening on, e.g.:
$ sudo netstat --inet -p -l | grep rpcbind | grep -v sunrpc
udp 0 0 0.0.0.0:614 0.0.0.0:*
4678/rpcbind
each time rpcbind is restarted, it will be listening to a different
'random' port.
[regression potential]
this adds a method to disable rpcbind from listening to the 'random'
port. any regression would likely prevent rpcbind from starting, or
may cause problems with the interaction between rpcinfo and rpcbind,
as rpcinfo may use the random reserved port in some cases, as detailed
in the Debian bug.
[scope]
This is needed only for Bionic and earlier.
In Focal and later, and in Debian, rpcbind defaults to not opening the
random reserved port. The admin can use the -r parameter to cause
rpcbind to restore the old behavior of opening the random reserved
port.
[other info]
Note that the -r parameter is a Debian addition, and the upstream
rpcbind has disabled the random port functionality at build time;
there is no runtime parameter to allow the admin to choose the
behavior.
Also, as discussed in the Debian bug, disabling this rpcbind 'feature'
is known to cause problems for the rpcinfo program, which is why
Debian introduced the -r parameter. So, when this -r parameter is
backported to Bionic and earlier, we must retain the default behavior
for those releases, which is for rpcbind to open the random reserved
port.
TBD: specific method to disable rmtcalls in backport
[original description]
As this backports that functionality, it
Binary package hint: cups
cups 1.3.9-2ubuntu4
From /var/log/cups/error_log:
cups: unable to bind socket for address 127.0.0.1:631 - Address already in
use.
Nothing actually looks wrong. 127.0.0.1:631 is only in use by cupsd
when started.
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