bin/164348: ntp.conf restrict default ignore option doesn't function as advertised

Garrett Cooper yanegomi at gmail.com
Sat Jan 21 09:20:06 UTC 2012


>Number:         164348
>Category:       bin
>Synopsis:       ntp.conf restrict default ignore option doesn't function as advertised
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Jan 21 09:20:06 UTC 2012
>Closed-Date:
>Last-Modified:
>Originator:     Garrett Cooper
>Release:        9.0-STABLE
>Organization:
n/a
>Environment:
FreeBSD bayonetta.local 9.0-STABLE FreeBSD 9.0-STABLE #4 r230371M: Thu Jan 19 23:55:38 PST 2012     gcooper at bayonetta.local:/usr/obj/store/freebsd/stable/9/sys/BAYONETTA  amd64
>Description:
While trying to lock down ntpd without a firewall, I was trying to do one of two things:

1. Get ntpd to listen only on localhost to avoid opening up potential security backdoors.
2. Get ntpd to listen to a select set of addresses.

Point was to get ntpd to function in a 'more secure' manner like ntpdate.

It doesn't seem that there's a 'listen only on select addresses option' available in ntpd, so 1. looks impossible. According to the documentation though, I should be able to restrict access to just localhost, so 2. should be doable [1]. In reality, this option doesn't seem to work as advertised, s.t. if I set 'restrict ignore default' it will reject all requests.

1. http://support.ntp.org/bin/view/Support/AccessRestrictions#Section_6.5.1.2.1.
>How-To-Repeat:
# sh
# cat > /etc/ntp.conf <<EOF
server 0.freebsd.pool.ntp.org iburst maxpoll 9
server 1.freebsd.pool.ntp.org iburst maxpoll 9
server 2.freebsd.pool.ntp.org iburst maxpoll 9

restrict default ignore
restrict 65.75.130.21
restrict 127.0.0.1
restrict -6 ::1
EOF
# service ntpd restart
>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted:


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