2000-12-04 17:00:32 +00:00
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Frequently Asked Questions about BIND 9
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2000-11-08 02:09:29 +00:00
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Q: Why doesn't -u work on Linux 2.2.x?
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A: Linux threads do not fully implement the Posix threads (pthreads) standard.
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In particular, setuid() operates only on the current thread, not the full
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process. Because of this limitation, BIND 9 cannot use setuid() on Linux as it
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can on all other supported platforms. setuid() cannot be called before
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creating threads, since the server does not start listening on reserved ports
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until after threads have started.
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In the 2.3.99-pre3 and newer kernels, the ability to preserve capabilities
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across a setuid() call is present. This allows BIND 9 to call setuid() early,
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while retaining the ability to bind reserved ports. This is a Linux-specific
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hack.
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On a 2.2 kernel, BIND 9 does drop many root privileges, so it should be less
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of a security risk than a root process that has not dropped privileges.
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If Linux threads ever work correctly, this restriction will go away.
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2000-11-08 17:12:10 +00:00
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2000-12-04 19:52:44 +00:00
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Configuring BIND9 with the --disable-threads option causes a non-threaded
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version to be built, which will allow -u to be used.
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2000-11-08 17:12:10 +00:00
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Q: Why does named log the error message "no TTL specified" and refuse
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to load my zone file?
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A: Your zone file must either have a line like
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$TTL 86400
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at the beginning, or the first record in it must have a TTL field,
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like the "84600" in this example:
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example.com. 86400 IN SOA ns hostmaster ( 1 3600 1800 1814400 3600 )
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BIND 8 incorrectly accepted files that had neither.
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2000-11-13 20:14:35 +00:00
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Q: Why do I see 5 (or more) copies of named on Linux?
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A: Linux threads each show up as a process under ps. The approximate
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number of threads running is n+4, where n is the number of CPUs.
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2000-11-16 18:09:48 +00:00
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Q: Why does BIND 9 log "permission denied" errors accessing its
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configuration files on my Linux sysetm even though it is running as
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root?
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A: On Linux, BIND 9 drops most of its root privileges on startup.
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This including the privilege to open files owned by other users.
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Therefore, if the server is running as root, the configuration files
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should also be owned by root.
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