JunOS NTP - Re: OpenNTPProject.org

Tue Feb 18 14:14:59 UTC 2014

So, be careful as the Juniper solution varies depending on the platform involved.

Make sure you check your devices.  It took a few iterations for us to get the right filters on everything.

- Jared

On Feb 17, 2014, at 12:26 AM, Yucong Sun <sunyucong at gmail.com> wrote:

> Just for the reference, here is a more complete solution for Junos (took me
> a while searching the web to figure it out), hope it helps someone.
> 
> policy-options {
>    prefix-list lo0.0-inet-address {
>        apply-path "interfaces lo0 unit 0 family inet address <*>";
>    }
>    prefix-list ntp-servers {
>        apply-path "system ntp server <*>";
>    }
> }
> 
> firewall {
>    family inet {
>        filter lo-filter {
>            term ntp-allow {
>                from {
>                    source-prefix-list {
>                        ntp-servers;
>                        lo0.0-inet-address;
>                    }
>                    protocol udp;
>                    destination-port ntp;
>                }
>                then accept;
>            }
>            term ntp-other-discard {
>                from {
>                    protocol udp;
>                    destination-port ntp;
>                }
>                then {
>                    discard;
>                }
>            }
>            term zz-accept {
>                then accept;
>            }
>        }
>   }
> }
> 
> 
> 
> On Sun, Feb 16, 2014 at 8:42 PM, Mark Tinka <mark.tinka at seacom.mu> wrote:
> 
>> On Monday, February 17, 2014 06:35:46 AM Lyndon Nerenberg
>> wrote:
>> 
>>> I was suggesting it as an alternative to just chopping
>>> off NTP at your border.  Presumably it would be a
>>> one-off thing until Juniper issues a patch.
>> 
>> In Junos, applying the right filters to your router's
>> control plane will fix the issue. You don't need to block
>> NTP in the data plane.
>> 
>> Mark.
>> 