02-02-2018
Forcing named 9 to use a fixed ephemeral port range
I'll start with I'm not an AIX expert, I inherited a lot of AIX servers to maintain.
My problem is on AIX 7.1 TL4 SP4 environments. I'm running named as a DNS forwarder only to internal DNS servers.
These AIX servers have a customized UDP ephemeral port range to avoid conflicting with the primary application running on them that defaults to a portion of the typical ephemeral range.
Since configuring named, I've seen that named is ignoring the OS configured ephemeral range.
The OS restricted UDP range is: 32768 to 49999.
I've seen requests from named using source ports above 49999.
After googling, the only article I can find that references named/bind and ephemeral ports is a page from ISC related to BIND 9. There's a setting "use-v4-udp-ports { range 1024 65535; };" that forces named to use a fixed UDP range for source ports. But the IBM documentation on named doesn't cover this option.
I tried putting the setting onto named.conf on a test system but now named won't start and no errors are logged.
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LEARN ABOUT PHP
named-checkconf
named-checkconf(1M) System Administration Commands named-checkconf(1M)
NAME
named-checkconf - named configuration file syntax checking tool
SYNOPSIS
named-checkconf [-v] [-t directory] filename
DESCRIPTION
The named-checkconf utility checks the syntax, but not the semantics, of a named configuration file.
OPTIONS
The following options are supported:
-t directory Change the root directory to directory so that include directives in the configuration file are processed as if run by a
named configuration whose root directory has been similarly changed.
-v Print the version of the named-checkconf program and exit.
OPERANDS
The following operands are supported:
filename The name of the configuration file to be checked. If not specified, it defaults to /etc/named.conf.
EXIT STATUS
0 No errors were detected.
1 An error was detected.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|Availability |SUNWbind9 |
|Interface Stability |External |
+-----------------------------+-----------------------------+
SEE ALSO
named(1M), named.conf(4), attributes(5)
BIND 9 Administrator Reference Manual
NOTES
Source for BIND9 is available in the SUNWbind9S package.
SunOS 5.10 15 Dec 2004 named-checkconf(1M)