TSIG with BIND requires chmod+chgrp /etc/namedb

Mark_Andrews at isc.org Mark_Andrews at isc.org
Fri Nov 1 23:01:14 UTC 2002


> 
> On 1 Nov 2002 at 17:07, Kevin Darcy wrote:
> 
> > 
> > Dan Langille wrote:
> > 
> > > On 1 Nov 2002 at 10:22, Cricket Liu wrote:
> > >
> > > >
> > > > Dan Langille wrote:
> > > > > It appears that using TSIG with BIND for secondary domains requires a
> > > > > chmod and chgrp of /etc/namedb.
> > > > >
> > > > > I've been adding TSIG to varioius domains.  But I've found that on my
> > > > > slave servers, I've had to set the directory permissions as this:
> > > > >
> > > > > $ ls -ld /etc/namedb/
> > > > > drwxrwxr-x  4 root  bind  512 Oct 15 09:26 /etc/namedb/
> > > > > $ ls -ld /etc/namedb/secondary/
> > > > > drwxr-x---  2 bind  bind  512 Oct 15 09:25 /etc/namedb/secondary/
> > > > >
> > > > > The original permissions on /etc/namedb are:
> > > > > drwxr-xr-x  2 root  wheel  512 Mar  9  2002 /etc/namedb
> > > > >
> > > > > named is running as:  /usr/sbin/named -u bind -g bind
> > > > >
> > > > > Some bits from /etc/namedb/named.conf:
> > > > >
> > > > > options {
> > > > >         directory "/etc/namedb";
> > > > >
> > > > > I don't really liked having to change the permission of /etc/namedb
> > > > > especially as that will be necessary for people runnning secondary
> > > > > DNS for me.
> > > > >
> > > > > Any comments/suggestions?
> > > > >
> > > > > [I'm using named 8.3.3-REL on FreeBSD 4.6-stable]
> > > >
> > > > I don't see why TSIG would require that the name server be able to
> > > > write to the working directory.  The name server would need to be
> > > > able to read the named.conf file or whatever file contained the key
> > > > definition, but that's it.
> > >
> > > It sounds like you do not believe me.... ;)
> > >
> > > Unless I do those chmod's, I get these errors:
> > >
> > > named[41288]: starting (/etc/namedb/named.conf).  named 8.3.3-REL Wed
> > > Jul 31 09:19:38 PDT 2002
> > > root at nezlok.example.org:/usr/obj/usr/src/usr.sbin/named
> > > named[41288]: limit files set to fdlimit (1024)
> > > named[41289]: Ready to answer queries.
> > > named[41289]: write_tsig_info: mkstemp(tsigs.i0FeEp) for TSIG info
> > > failed
> > > named[41289]: unable to write tsig info: 'example.com'
> > 
> > Yeah, it appears that BIND 8 writes TSIG keys into a temporary file. In
> > 20/20 hindsight, perhaps it would have been smarter for it to chdir() into
> > the directory of the associated inbound zone transfer.
> > 
> > NOTE: I just tested BIND 9.2.2rc1 in this scenario and it doesn't appear to
> > have the same problem. So I guess the short answer is "upgrade".
> 
> Thanks for that information.  Unfortunately, upgrading isn't an 
> option as the slave servers in question are run by other people.   I 
> can't ask them to upgrade just to cater for my TSIG wishes.  I'll 
> have to find another solution.
> -- 
> Dan Langille
> 

	Remember that there is nothing actually wrong with named writing
	to its working directory.  named.run is written there by default
	as is named_dump.db, named.memstats and any core file.

	Writing to "/tmp" is actually more of a security risk as it is
	writable by everyone.  The working directory shouldn't be.

	In general named should be able to write to its working directory.

	If I was chrooted and was worried about it I would have

	/etc/namedb/slave/	(writable by named)
	/etc/namedb/master/	(readable by named)
	/etc/namedb/etc/	(readable by named)
	/etc/namedb/scratch/	(writable by named)
	
	named -t /etc/namedb -u named -g named 

	options {
		directory "/scratch";
		pid-file "named.pid";
		...
	}
	
	zone ... {
		type master;
		file "/master/...";
	};
	
	zone ... {
		type slave;
		file "/slave/...";
		masters { ... };
	};

	Mark
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at isc.org


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