Do you need configure lo0 unit 0 with

set security zones security-zone trust interface lo0.0
set security zones security-zone host-inbound-interfaces system-services ping

Do you have to do this for any security zone interface to accept ANY kind of service (not just pings but routing protocols too)?

1 Answer 1


In the Junos running in flow mode which is the default case, you need to assign the interface to security zone to be functional that inlclude the lo0 interface And for protocols you need to enable the protocols :

Ex: set security zone security-zone trust interface lo0 host-inbound-interfaces protocols ospf
  • Hey, so would it be safe to say, I should just enable EVERYthing for EVERY interface I am planning on using? Oct 13, 2017 at 0:06
  • Basically, Juniper has you configure things that Cisco is already allowing right out of the box? Oct 13, 2017 at 0:07
  • You can enable the protocols either for incoming connections eother on zone level or interface level ...if the interface not assigned to zone you can't even send traffic out of it
    – Mr.lock
    Oct 13, 2017 at 6:56
  • @JoshGarmon47 this is only relevant to the SRX line which is a security device. You have to remember that on any Juniper box, the loopback is also the logical interface that represents direct connectivity to the routing-engine/control-plane of the box, so filtering all traffic by default is a perfectly sane default setting. Oct 14, 2017 at 12:06
  • The problem I'm seeing is my J2320 routers have "SRX Like" attributes to them. I couldn't even get DIRECTLY connected routers to even PING each other until I configured that security zone stuff and allowed ping. Oct 14, 2017 at 18:07

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