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Juniper SRX security zones provide the ability to assign networks with different security requirements to different security zones, which is a prerequisite for controlling traffic between networks.

It is also possible to control traffic from different security domains to the Juniper device itself and vice versa, from the Juniper device to different security domains, which is a further discussion of this section.

Juniper SRX security zones Fundamental

The first of configuring security policy is to configure security zones and assign interfaces to the zones.

Juniper SRX Security Zones concept
Juniper SRX Security Zones concept

All interfaces with common security requirements are configured in the same security zones. In other words, to control traffic between two security domains, they must be in different security zones.

All traffic between networks in the same security zone are allowed.

In this topology, LAN1 and LAN2 have the same security requirement. therefore they are in the same security zone, Trust.

Interfaces connected to the LAN and WAN have the same security requirements and therefore they are in the same security zone, untrust zone.

Interface connected to the datacenter is located in another security zone, DMZ. zone.

We can control traffic between theses three zones.

Juniper SRX Zone Types

There are four types of zones in juniper SRX device. “Functional-zone” (management zone), “security zone”, “junos-host” zone and “null” zone.

Juniper SRX Zone Types
Juniper SRX Zone Types

By default, all interfaces are in the null zone. All traffic received on interfaces in the null zones are discarded. In other words, to start forwarding traffic through an interface, it must be assigned to a security zone.

you can assign an interface to functional management zone. this interface can be used only for the purpose of management like telnet, SSH and web interface.

Traffic cannot be routed and forwarded through the management interface and the destination of management traffic can only be the Juniper device itself.

The use of management zone can be useful in small SRX devices which do not have a dedicated out of band management interface. Therefore you can dedicate an interface just for the purpose of management with assigning it to the management zone.

Junos-host zone is to control traffic between any zone and juniper device itself. By default all traffic from any zone to the  juniper device itself are discarded. And all traffic from the juniper device itself to all zones are permitted by default.

Security zone is the main type of zone with security purposes. All interfaces with the same security requirements are assigned to the same security zones. And therefore interfaces with different security requirements are assigned to different security zones.

You are allowed to control traffic only between different security zones.

Juniper SRX Zone Topology

This is the topology based on which we will configure security zones.

Juniper SRX Security Zones Topology
Juniper SRX Security Zones Topology

Juniper SRX is connected to the internet through interface ge-0/0/0 with IP address 192.168.1.250/24. interface ge-0/0/0 will be assigned to security zone “outside”.

Interface ge-0/0/1 is connected to LAN network with IP address 192.168.10.0/24. interface ge-0/0/1 is assigned to security zone “inside”.

Interface fxp0 is management interface in juniper SRX on which we will connect to configure the device. Th IP address of management interface is 192.168.200.101/24.

Preparing juniper SRX device

Before starting the configuration, I have removed all the configuration from juniper SRX device with “request system zeroize” command.

Then I have added these configuration just to initiate the device for remote connection and prepare it for security zone configuration.

> request system zeroize

set system root-authentication plain-text-password 
set system login user rayka class super-user
set system login user rayka authentication plain-text-password
set system services ssh root-login allow
set system services telnet
set system services web-management https interface fxp0.0
set system services web-management https system-generated-certificate
set interfaces fxp0 unit 0 family inet address 192.168.200.101/24

A password is configured for root user.

A new username with root privilege is created.

SSH, telnet and web remote access is activated.

Finally the IP address of management interface is configured to 192.168.200.101/24 as we have displayed in the topology.

Juniper SRX security zones configuration

With command “set security zones ?” in configuration mode, you can see that there two types of zones that can be configured. “functional-zone” and “security-zone”.

rayka# set security zones ?
Possible completions:
+ apply-groups         Groups from which to inherit configuration data
+ apply-groups-except  Don't inherit configuration data from these groups
> functional-zone      Functional zone
> security-zone        Security zones
[edit]

functional-zone management in juniper SRX

There is only one option with functional-zone and that is management, it means you can assign and dedicated an interface to management interface.

Management interface is just to connect to the device for management purposes.

Management-zone is useful mostly for small SRX devices that do not have dedicated out of band management interface.

Here in vSRX, fxp0 interface is dedicated to management-only purposes.

But just to show how one interface is added to management interface, I add interface ge-0/0/2 to functional-zone management.

rayka# set security zones functional-zone management interfaces ge-0/0/2

rayka# rollback 0 

With command “rollback 0”, I will delete management interface configuration, since we do not need it in our topology.

configure security zones and assign interfaces to security zones

With command “set security zones security-zone ?”, you can see that by default there are two security zones “untrust” and “trust” but I will nit use them here and I will create my own security zones, “outside” and “inside” as in the topology.

rayka# set security zones security-zone ?
Possible completions:
  <name>               Name of the zone
  trust                Name of the zone
  untrust              Name of the zone
[edit]
rayka# set security zones security-zone inside 

[edit]
rayka# set security zones security-zone outside 

After creating security zones, I have to assign interfaces to security zones.

First I, will configure the IP address of ge-0/0/0 and ge-0/0/1 as in the topology. then I will add the interface ge-0/0/0 in outside security zone and interface ge-0/0/1 in inside security zone.

rayka# set interfaces ge-0/0/0 unit 0 family inet address 192.168.1.250/24    

[edit]
rayka# set interfaces ge-0/0/1 unit 0 family inet address 192.168.10.250/24 

[edit]
rayka# set security zones security-zone outside interfaces ge-0/0/0 

[edit]
rayka# set security zones security-zone inside interfaces ge-0/0/1

To check the status of security zones, with command “show security zones terse” in operational mode, you can list all configured security zones.

[edit]
rayka# run show security zones terse 
Zone                        Type
inside                      Security
outside                     Security
trust                       Security
untrust                     Security
junos-host                  Security

With command “show security zones”, you can also check which interfaces are assigned to each security zone.

[edit]
rayka# run show security zones          

Security zone: inside
  Zone ID: 11
  Send reset for non-SYN session TCP packets: Off
  Policy configurable: Yes  
  Interfaces bound: 1
  Interfaces:
    ge-0/0/1.0
  Advanced-connection-tracking timeout: 1800
  Unidirectional-session-refreshing: No

Security zone: outside
  Zone ID: 10
  Send reset for non-SYN session TCP packets: Off
  Policy configurable: Yes  
  Interfaces bound: 1
  Interfaces:
    ge-0/0/0.0
  Advanced-connection-tracking timeout: 1800
  Unidirectional-session-refreshing: No

Security zone: trust
  Zone ID: 7
  Send reset for non-SYN session TCP packets: On
  Policy configurable: Yes  
  Interfaces bound: 0
  Interfaces:
  Advanced-connection-tracking timeout: 1800
  Unidirectional-session-refreshing: No

Security zone: untrust
  Zone ID: 8
  Send reset for non-SYN session TCP packets: Off
  Policy configurable: Yes  
  Screen: untrust-screen  
  Interfaces bound: 0
  Interfaces:
  Advanced-connection-tracking timeout: 1800
  Unidirectional-session-refreshing: No

Security zone: junos-host
  Zone ID: 2
  Send reset for non-SYN session TCP packets: Off
  Policy configurable: Yes  
  Interfaces bound: 0
  Interfaces:
  Advanced-connection-tracking timeout: 1800
  Unidirectional-session-refreshing: No 

[edit]
rayka# 

configure juniper security zone host-inbound-traffic

As I have explained previously, by default, all traffic from any security zone to the juniper itself are discarded but all traffic from juniper device itself to any security zone are permitted by default.

The parameter “host-inbound-traffic” is to configure which traffic are permitted to the juniper device itself.

This parameter can be configured in security zone level or a specific interface in security zone.

[edit]
rayka# set security zones security-zone outside host-inbound-traffic ...

[edit]
rayka# set security zones security-zone outside interfaces ge-0/0/0 host-inbound-traffic ...

As we can guess, what is configured in security zone interface level is preferred to what is configured in the security zone level.

There are two parameters in “host-inbound-traffic” section, “protocols” and “system-services”.

With protocols option, you can permit protocol traffics like “OSPF”, “IGMP” and “PIM” to the juniper device itself.

With system-services option, you can allow services like ping, SSH, Telnet and SNMP to the juniper device.

[edit]
rayka# set security zones security-zone outside host-inbound-traffic ?
Possible completions:
+ apply-groups         Groups from which to inherit configuration data
+ apply-groups-except  Don't inherit configuration data from these groups
> protocols            Protocol type of incoming traffic to accept
> system-services      Type of incoming system-service traffic to accept
[edit]
rayka# set security zones security-zone outside host-inbound-traffic protocols ?  
Possible completions:
  all                  All protocols
  bfd                  Bidirectional Forwarding Detection
  bgp                  Border Gateway Protocol
  dvmrp                Distance Vector Multicast Routing Protocol
  igmp                 Internet Group Management Protocol
  ldp                  Label Distribution Protocol
  msdp                 Multicast Source Discovery Protocol
  nhrp                 Next Hop Resolution Protocol
  ospf                 Open Shortest Path First
  ospf3                Open Shortest Path First version 3
  pgm                  Pragmatic General Multicast
  pim                  Protocol Independent Multicast
  rip                  Routing Information Protocol
  ripng                Routing Information Protocol next generation
  router-discovery     Router Discovery
  rsvp                 Resource Reservation Protocol
  sap                  Session Announcement Protocol
  vrrp                 Virtual Router Redundancy Protocol

[edit]
rayka# set security zones security-zone outside host-inbound-traffic system-services ?
Possible completions:
  all                  All system services
  any-service          Enable services on entire port range
  appqoe               APPQOE active probe service
  bootp                Bootp and dhcp relay-agent service
  dhcp                 Dynamic Host Configuration Protocol
  dhcpv6               Enable Dynamic Host Configuration Protocol for IPv6
  dns                  DNS service
  finger               Finger service
  ftp                  FTP
  high-availability    High Availability service
  http                 Web management service using HTTP
  https                Web management service using HTTP secured by SSL
  ident-reset          Send back TCP RST to IDENT request for port 113
  ike                  Internet Key Exchange
  lsping               Label Switched Path ping service
  lsselfping           Label Switched Path self ping service
  netconf              NETCONF service
  ntp                  Network Time Protocol service
  ping                 Internet Control Message Protocol echo requests
  r2cp                 Enable Radio-Router Control Protocol service
  reverse-ssh          Reverse SSH service
  reverse-telnet       Reverse telnet service
  rlogin               Rlogin service
  rpm                  Real-time performance monitoring
  rsh                  Rsh service
  snmp                 Simple Network Management Protocol service
  snmp-trap            Simple Network Management Protocol traps
  ssh                  SSH service
  tcp-encap            Tcp encapsulation service
  telnet               Telnet service
  tftp                 TFTP
  traceroute           Traceroute service
  webapi-clear-text    Webapi service using http
  webapi-ssl           Webapi service using HTTP secured by SSL
  xnm-clear-text       JUNOScript API for unencrypted traffic over TCP
  xnm-ssl              JUNOScript API service over SSL

As an example , I will add all protocols and all system services in security zone level to be allowed. But in security zone interface level, I will add only OSPF protocol and I will exempt telnet service from all system-services with “except” parameter.

[edit]
rayka# set security zones security-zone inside host-inbound-traffic system-services all 

[edit]
rayka# set security zones security-zone inside host-inbound-traffic protocols all          


[edit]
rayka# set security zones security-zone outside interfaces ge-0/0/0 host-inbound-traffic protocols ospf     

[edit]
rayka# set security zones security-zone outside interfaces ge-0/0/0 host-inbound-traffic system-services all      

[edit]
rayka# set security zones security-zone outside interfaces ge-0/0/0 host-inbound-traffic system-services telnet except 

[edit]
rayka# show | compare 
[edit security zones security-zone outside]
+     host-inbound-traffic {
+         system-services {
+             all;
+         }
+         protocols {
+             all;
+         }
+     }
[edit security zones security-zone outside interfaces ge-0/0/0.0]
+      host-inbound-traffic {
+          system-services {
+              telnet {
+                  except;
+              }
+              all;
+          }
+          protocols {
+              ospf;
+          }
+      }
[edit security zones security-zone inside]
+     host-inbound-traffic {
+         system-services {
+             all;
+         }
+         protocols {
+             all;
+         }
+     }

[edit]
rayka# 

Now we expect that we can ping the juniper device.

C:\Users\raykaremote>ping 192.168.1.250

Pinging 192.168.1.250 with 32 bytes of data:
Reply from 192.168.1.250: bytes=32 time=3ms TTL=65
Reply from 192.168.1.250: bytes=32 time<1ms TTL=64
Reply from 192.168.1.250: bytes=32 time<1ms TTL=64
Reply from 192.168.1.250: bytes=32 time<1ms TTL=64

Ping statistics for 192.168.1.250:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 3ms, Average = 0ms

C:\Users\raykaremote>

However it not the discussion of this section but just to show you the application of “junos-host” zone, I want to reject “ICMP” traffic to the juniper device but not with “host- host-inbound-traffic”.

I will configure it with writing a security policy from zone “outside” to the “junos-host” zone which is juniper device itself.

set security policies from-zone outside to-zone junos-host policy deny-icmp match source-address any
set security policies from-zone outside to-zone junos-host policy deny-icmp match destination-address any
set security policies from-zone outside to-zone junos-host policy deny-icmp match application junos-icmp-ping
set security policies from-zone outside to-zone junos-host policy deny-icmp then reject


[edit]
rayka# show | compare 
[edit security policies]
     from-zone trust to-zone untrust { ... }
+    from-zone outside to-zone junos-host {
+        policy deny-icmp {
+            match {
+                source-address any;
+                destination-address any;
+                application junos-icmp-ping;
+            }
+            then {
+                reject;
+            }
+        }
+    }

[edit]

Now we expect that we can not ping the juniper device from outside anymore.

C:\Users\raykaremote>ping 192.168.1.250

Pinging 192.168.1.250 with 32 bytes of data:
Reply from 192.168.1.250: Destination port unreachable.
Reply from 192.168.1.250: Destination port unreachable.
Reply from 192.168.1.250: Destination port unreachable.
Reply from 192.168.1.250: Destination port unreachable.

Ping statistics for 192.168.1.250:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Back to: Juniper Security Associate (JNCIA-SEC) (in Progress) > Junos Security Objects

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