Is there any ntpd that can be configured to listen to selected interfaces only? -
my situation is, configure many virtual network interfaces virtual machines , of networks have 2 or more addresses. don't need ntpd
listen these interfaces, there seems no option restrict interfaces ntpd tries bind to. besides these "security" options in ntpd, system administrator, knows environment, best security option not listen @ interfaces. example more secure not listen external interfaces @ all, restrict access through ntp configuration.
is there ntpd software known can configured listen selected interfaces (as network daemon should)?
there 2 easy ways this, both documented in official ntp documentation:
use
-i
command line option ntpd invocation-i [address | interface name] open network address given, or addresses associated given interface name. option may appear multiple times. option implies not opening other addresses, except wildcard , local‐ host. option deprecated. please consider using configuration file interface command, more versatile.
use
interface
directive in ntp.conf:interface [listen | ignore | drop] [all | ipv4 | ipv6 | wildcard | name | address[/prefixlen]] command controls network addresses ntpd opens, , whether input dropped without processing. first parameter determines action addresses match second parameter. parameter specifies class of addresses, or specific interface name, or address. in address case, prefixlen determines how many bits must match rule apply. ignore prevents opening matching addresses, drop causes ntpd open address , drop received packets without examination. multiple interface commands can used. last rule matches particular address determines action it. interface commands disabled if -i, --interface, -l, or --novirtualips command-line options used. if none of options used , no interface actions specified in configuration file, available network addresses opened. nic command alias interface.
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