[debian-mysql] Bug#664846: mysql-server-5.1: MySQL Server does DNS-PTR lookups even when skip-name-resolve is active

Bjoern Boschman bjoern.boschman at nfon.net
Wed Mar 21 10:25:48 UTC 2012

Package: mysql-server-5.1
Version: 5.1.61-0+squeeze1
Severity: important

Hi folks,

I'm running my MySQL server with the --skip-name-resolve.
I verified that this option is enabled via:

mysql> show variables LIKE 'skip_name_resolve'\G
*************************** 1. row ***************************
Variable_name: skip_name_resolve
        Value: ON
1 row in set (0.00 sec)

Unfortunatelly SQL connections from remote hosts are very slow in the handshake phase.
I found that this is the case for hosts where no PTR record is set.

After that I started a tcpdump on the mysql-server host looking for DNS queries
and I see several PTR lookup each time a remote client wants to connect.

If you need more information do not hesitate to contact me.


-- System Information:
Debian Release: 6.0
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.32-5-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages mysql-server-5.1 depends on:
ii  adduser     3.112+nmu2                   add and remove users and groups
ii  debconf [de                     Debian configuration management sy
ii  libc6       2.11.2-10                    Embedded GNU C Library: Shared lib
ii  libdbi-perl 1.612-1                      Perl Database Interface (DBI)
ii  libgcc1     1:4.4.5-8                    GCC support library
ii  libmysqlcli 5.1.61-0+squeeze1            MySQL database client library
ii  libstdc++6  4.4.5-8                      The GNU Standard C++ Library v3
ii  lsb-base    3.2-23.2squeeze1             Linux Standard Base 3.2 init scrip
ii  mysql-clien 5.1.61-0+squeeze1            MySQL database client binaries
ii  mysql-commo 5.1.61-0+squeeze1            MySQL database common files, e.g. 
ii  mysql-serve 5.1.61-0+squeeze1            MySQL database server binaries
ii  passwd      1: change and administer password and
ii  perl        5.10.1-17                    Larry Wall's Practical Extraction 
ii  psmisc      22.11-1                      utilities that use the proc file s
ii  zlib1g      1:             compression library - runtime

Versions of packages mysql-server-5.1 recommends:
ii  heirloom-mailx [mailx]        12.4-2     feature-rich BSD mail(1)
ii  libhtml-template-perl         2.9-2      module for using HTML Templates wi

Versions of packages mysql-server-5.1 suggests:
pn  tinyca                        <none>     (no description available)

-- debconf information excluded

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