Example: Configuring Hub-and-Spoke VPNs using Next-Hop Tunnel Binding

This example shows how to configure, verify, and troubleshoot the hub-and-spoke VPNs using next-hop tunnel binding.

  • Configuration and troubleshooting details of route-based virtual private networks (VPNs) and other Junos OS specific application notes are available on the Juniper Networks Knowledge Base at http://kb.juniper.net.
  • For more information on the concepts of NHTB, route-based VPNs, and interface types, refer to the complete documentation for Junos OS available at http://www.juniper.net/techpubs/.
  • For more information on VPN configuration and troubleshooting, see KB10182 (http://kb.juniper.net/KB10182) available at Juniper Networks Knowledge Base.

This topic includes the following sections:

Requirements

Overview and Topology

Figure 2 shows the network topology used for this example.

Figure 2: Network Topology

Image g040513.gif

This example assumes the following settings:

Basic Configuration Steps for Hub and Spoke Devices

This topic includes the following sections:

Basic Steps to Configure the Hub (Device in Corporate Office)

Step-by-Step Procedure

The basic steps to configure the hub (device in the Corporate office) are:

  1. Configure the IP addresses for the ge-0/0/0.0, ge-0/0/3.0, and st0.0 interfaces.
  2. Configure the default route to the Internet next hop and also configure static routes for each remote office LAN.

    Note: Optionally, you can use a dynamic routing protocol such as OSPF to configure the routes automatically, but that is beyond the scope of this example.

  3. Configure the security zones, and bind the interfaces to the appropriate zones. Ensure that you have enabled the necessary host-inbound services on the interfaces or the zone. In this example, you must enable Internet Key Exchange (IKE) service on either the ge-0/0/3 interface or to the zone untrust.
  4. Configure address book entries for each zone.
  5. Configure Phase 1 (IKE) gateway settings for both e remote offices. This example uses a standard proposal set. However, you can create a different proposal set, if required.
  6. Configure Phase 2 IP Security- virtual private network (IPsec VPN) settings for both remote offices. Optionally, you can also configure the VPN monitor settings, if required. This example uses a standard proposal set, and Perfect Forward Secrecy (PFS) group 2. However, you can create a different proposal set, if required.

  7. Bind the st0.0 interface to the IPsec VPN.
  8. Configure the st0.0 for a multipoint interface. Configure the NHTB entries for any non-Junos spoke sites.

    Note: If you are establishing a VPN between two Junos devices, then it is not necessary to configure an NHTB because the hub device can obtain the NHTB entry automatically during Phase 2 negotiations. However, if you have configured the VPN to establish tunnel on-traffic, then the hub site cannot initiate the VPN. Without an NHTB entry, the route for that remote peer would not be in active state.

    In this scenario, either the tunnel must always be initiated from the spoke, or the hub device must have the establish-tunnel field configured to be activated immediately after the configuration changes are committed.

  9. Configure security policies to permit remote office traffic into the host LAN (Corporate office) and vice versa.
  10. Configure an outgoing trust to untrust permit-all policy with source Network Address Translation (NAT) for non-encrypted Internet traffic
  11. Configure an intrazone policy in zone vpn to allow spokes to communicate with each other. Intrazone traffic is defined as traffic that ingresses (incoming) and egresses (outgoing) traffic through the same zone. By default intrazone traffic is denied.
  12. Configure TCP maximum segment size (MSS) for IPsec traffic to eliminate the possibility of fragmented TCP traffic. This step reduces the resource usage on the device.

Basic Steps to Configure the Spoke (Device in Westford Office)

Step-by-Step Procedure

The basic steps to configure the spoke (device in the Westford office) are:

  1. Configure the IP addresses for the ge-0/0/0.0, ge-0/0/3.0 and st0.0 interfaces.
  2. Configure the default route to the Internet next hop, and also configure a static route for the Corporate office LAN.
  3. Configure security zones and bind the interfaces to the appropriate zones. Also ensure that necessary host-inbound services are enabled on the interfaces or the zone.

    In this example, you must enable IKE service on either the ge-0/0/0 interface or to the zone untrust.

  4. Configure address book entries for each zone.
  5. Configure Phase 1 (IKE) gateway settings. This example uses a standard proposal set.
  6. Configure Phase 2 (IPsec) VPN settings.
  7. Bind the st0.0 interface to the IPsec VPN.

    This example uses a standard proposal set and PFS group 2.

  8. Configure security policies to permit remote office (Westford office) traffic into the host LAN (Corporate office) and vice versa.
  9. Configure an outgoing trust to untrust permit-all policy with source NAT for non-encrypted Internet traffic
  10. Configure the TCP-MSS for IPsec traffic to eliminate the possibility of fragmented TCP traffic and to reduce the resource usage on the device

Example: Configuring the Multipoint VPN Configuration with Next-Hop Tunnel Binding

This topic includes the following sections:

Example: Configuring the Hub (Corporate Office)

Step-by-Step Procedure

  1. Configure the IP addresses for the private LAN, public Internet, and the secure tunnel (st0) interfaces.

    Note: Junos OS uses the concept of units for the logical component of an interface. This example uses unit 0 and family inet (IPv4). We recommend configuring IP addresses for all peer devices within the same logical subnet (for st0 interfaces).

    [edit]user@hub# set interfaces ge-0/0/0 unit 0 family inet address 10.10.10.1/24user@hub# set interfaces ge-0/0/3 unit 0 family inet address 1.1.1.2/30user@hub# set interfaces st0 unit 0 family inet address 10.11.11.10/24
  2. Configure a default route and other static routes for tunnel traffic.

    For a static route, you can normally specify the gateway IP address as the next-hop. For route-based VPNs with multipoint interface, you can specify the remote peer st0 interface IP address as the next hop.

    [edit]user@hub# set routing-options static route 0.0.0.0/0 next-hop 1.1.1.1user@hub# set routing-options static route 192.168.168.0/24 next-hop 10.11.11.11user@hub# set routing-options static route 192.168.178.0/24 next-hop 10.11.11.12
  3. Configure the security zones, and assign interfaces to the zones.

    Creating a unique zone for tunnel traffic enables you to create a specific set of policies for VPN traffic while maintaining a separate set of policies for non-VPN traffic. Also, you can create deny policies to prevent certain hosts from accessing the VPN.

    No additional security policies are required, if:

    • You terminate the st0 interface in the same zone as the trusted LAN.
    • A policy is available that allows intrazone traffic in the same zone as the trusted LAN.
    [edit]user@hub# set security zones security-zone trust interfaces ge-0/0/0.0user@hub# set security zones security-zone untrust interfaces ge-0/0/3.0user@hub# set security zones security-zone vpn interfaces st0.0
  4. Configure host-inbound services for each zone.

    Host-inbound services are for traffic destined for the Junos device. These settings include but are not limited to the FTP, HTTP, HTTPS, IKE, ping, rlogin, RSH, SNMP, SSH, Telnet, TFTP, and traceroute.

    In this example, we are assuming that all host-inbound services should be allowed from zone trust. For security reasons, we are allowing IKE only on the Internet-facing zone untrust, which is required for IKE negotiations to occur. However, you can enable other individual services, such as services for management, or services for troubleshooting, if required.

    [edit]user@hub# set security zones security-zone trust host-inbound-traffic system-services alluser@hub# set security zones security-zone untrust host-inbound-traffic system-services ike
  5. Configure the address book entries for each zone.

    In this example, we are using addressbook object names such as local-net, sunnyvale-net, and westford-net. Additional address book entries can added for any additional spokes, if required.

    [edit]user@hub# set security zones security-zone trust address-book address local-net 10.10.10.0/24user@hub# set security zones security-zone vpn address-book address sunnyvale-net 192.168.168.0/24user@hub# set security zones security-zone vpn address-book address westford-net 192.168.178.0/24
  6. Configure the IKE policy for main mode, predefined standard proposal set, and preshared key.

    In this example, we are using the standard proposal set, which includes the esp-group2-3des-sha1 and esp-group2- aes128-sha1 proposals. However, you may create a unique proposal and then specify it in the IKE policy in accordance with your corporate security policy.

    The same IKE policy can be used for all spoke VPNs, if needed.

    [edit]user@hub# set security ike policy ike-policy1 mode mainuser@hub# set security ike policy ike-policy1 proposal-set standarduser@hub# set security ike policy ike-policy1 pre-shared-key ascii-text "secretkey"
  7. Configure the spoke IKE gateways (Phase 1) with a peer IP address, an IKE policy, and an outgoing interface.

    A remote IKE peer can be identified by:

    • IP address
    • Fully qualified domain name / user-fully qualified domain name (FQDN/U-FQDN)
    • ASN1-DN (public key infrastructure [PKI] certificates)

    In this example, we are identifying the peer by IP address. Therefore the gateway address should be the remote peer’s public IP address. You must also specify the correct external interface or peer ID to properly identify the IKE gateway during Phase 1 setup.

    [edit]user@hub# set security ike gateway westford-gate ike-policy ike-policy1user@hub# set security ike gateway westford-gate address 3.3.3.2user@hub# set security ike gateway westford-gate external-interface ge-0/0/3.0user@hub# set security ike gateway sunnyvale-gate ike-policy ike-policy1user@hub# set security ike gateway sunnyvale-gate address 2.2.2.2user@hub# set security ike gateway sunnyvale-gate external-interface ge-0/0/3.0
  8. Configure the IPsec policy.

    In this example, we are using the standard proposal set, which includes the esp-group2-3des-sha1 and esp-group2- aes128-sha1 proposals. However, you may create a unique proposal and then specify it in the IPsec policy, if needed.

    [edit]user@hub# set security ipsec policy vpn-policy1 proposal-set standarduser@hub# set security ipsec policy vpn-policy1 perfect-forward-secrecy keys group2
  9. Configure the IPsec VPN with an IKE gateway and IPsec policy, and bind them to the same st0 interface.

    Binding an st0 interface indicates that the VPN is a route-based VPN.

    You must specify an st0 interface to successfully complete Phase 2 negotiations for route-based VPNs.

    [edit]user@hub# set security ipsec vpn westford-vpn ike gateway westford-gateuser@hub# set security ipsec vpn westford-vpn ike ipsec-policy vpn-policy1user@hub# set security ipsec vpn westford-vpn bind-interface st0.0user@hub# set security ipsec vpn sunnyvale-vpn ike gateway sunnyvale-gateuser@hub# set security ipsec vpn sunnyvale-vpn ike ipsec-policy vpn-policy1user@hub# set security ipsec vpn sunnyvale-vpn bind-interface st0.0
  10. Configure the st0 interface as multipoint interface, then add a static NHTB entry for the spoke in the Sunnyvale office, which is an SSG device running ScreenOS. Because the spoke in the Sunnyvale office is not a Junos device, a static NHTB entry is required. You can also configure a static NHTB entry for another spoke in the Westford office if required (optional).
    user@hub# set interfaces st0 unit 0 multipointuser@hub# set interfaces st0 unit 0 family inet next-hop-tunnel 10.11.11.11 ipsec-vpn sunnyvale-vpn
  11. Configure bidirectional security policies for tunnel traffic for all spokes.

    In this example, a security policy permits traffic in one direction but it also allows all reply traffic without the need for a reverse direction policy. However, since traffic may be initiated from either direction, bi-directional policies are required.

    • If required, more granular policies can be created to permit/deny certain traffic.
    • Because the policies are regular non-tunnel policies, they do not specify the IPsec profile.
    • Source NAT can be enabled on the policy if desired, but that is beyond the scope of this example.
    • If more spoke sites are added, you can add the additional source/destination match entries for the new spoke local LANs to permit the traffic.
    [edit]user@hub# edit security policies from-zone trust to-zone vpn[edit security policies from-zone trust to-zone VPN]user@hub# set policy local-to-spokes match source-address local-netuser@hub# set policy local-to-spokes match destination-address sunnyvale-netuser@hub# set policy local-to-spokes match destination-address westford-netuser@hub# set policy local-to-spokes match application anyuser@hub# set policy local-to-spokes then permitExit
    [edit]user@hub# edit security policies from-zone vpn to-zone trust[edit security policies from-zone vpn to-zone trust]user@hub# set policy spokes-to-local match source-address sunnyvale-netuser@hub# set policy spokes-to-local match source-address westford-netuser@hub# set policy spokes-to-local match destination-address local-netuser@hub# set policy spokes-to-local match application anyuser@hub# set policy spokes-to-local then permit
  12. Configure a security policy for Internet traffic.

    A security policy is required to permit all traffic from zone trust to zone untrust.

    The device uses the specified source-nat interface, and translates the source IP address and port for outgoing traffic, using the IP address of the egress interface as the source IP address and using a random higher port for the source port. If required, you can create more granular policies to permit or deny certain traffic.

    [edit]user@hub# edit security policies from-zone trust to-zone untrust[edit security policies from-zone trust to-zone untrust]user@hub# set policy any-permit match source-address anyuser@hub# set policy any-permit match destination-address anyuser@hub# set policy any-permit match application anyuser@hub# set policy any-permit then permit source-nat interface
  13. Configure an intrazone policy in the vpn zone for spoke-to-spoke traffic.

    This policy permits all traffic from zone vpn to zone vpn, which is intrazone traffic. You must configure an intra-zone policy to allow traffic through one spoke to another without dropping any traffic. If required, you can create more granular policies to permit or deny certain IP prefixes or protocols.

    [edit]user@hub# edit security policies from-zone vpn to-zone vpn[edit security policies from-zone vpn to-zone vpn]user@hub# set policy spoke-to-spoke match source-address anyuser@hub# set policy spoke-to-spoke match destination-address anyuser@hub# set policy spoke-to-spoke match application anyuser@hub# set policy spoke-to-spoke then permit
  14. Configure the TCP MSS to eliminate the fragmentation of TCP traffic across the tunnel.

    TCP MSS is negotiated as part of the TCP three-way handshake. It limits the maximum size of a TCP segment to accommodate the maximum transmission unit (MTU) limits on a network. This is very important for VPN traffic, because the IPsec encapsulation overhead, along with the IP and Frame overhead, can cause the resulting ESP packet to exceed the MTU of the physical interface, resulting in fragmentation. Fragmentation increases the bandwidth and device resource usage, and should always be avoided. The recommended value for TCM MSS is 1350 for most Ethernet-based networks with an MTU of 1500 or higher. This value may need to be altered if any device in the path has a lower MTU value or if there is any added overhead such as PPP, or Frame Relay. As a general rule, you may need to experiment with different TCP MSS values to obtain optimal performance.

    user@hub# set security flow tcp-mss ipsec-vpn mss 1350

Example: Configuring the Spoke (Westford Office)

Step-by-Step Procedure

  1. Configure the IP addresses for the private LAN, public Internet, and the secure tunnel (st0) interfaces.

    Note: The steps for configuring the spoke device (Westford office) are similar to steps for configuring the hub device (Corporate office).

    Note: We recommend configuring IP addresses for all peer-devices within the same logical subnet (for st0 interfaces). Thus, the spoke device (Westford office) st0 interface is configured within the same subnet as the hub device (Corporate office) st0 interface.

    user@spoke# set interfaces ge-0/0/0 unit 0 family inet address 3.3.3.2/30user@spoke# set interfaces ge-0/0/3 unit 0 family inet address 192.168.178.1/24user@spoke# set interfaces st0 unit 0 family inet address 10.11.11.12/24
  2. Configure a default route and other static routes for the tunnel traffic.

    Because the device in Westford office is in a spoke site, the st0 interface type is point-to-point. Therefore, while configuring the next-hop option, you can specify the IP address of the st0 interface on the hub site, or you can specify st0.0 as the next hop.

    user@spoke# set routing-options static route 0.0.0.0/0 next-hop 1.1.1.1user@spoke# set routing-options static route 10.10.10.0/24 next-hop 10.11.11.10user@spoke# set routing-options static route 192.168.168.0/24 next-hop 10.11.11.10
  3. Configure the security zones and assign interfaces to the security zones.
    user@spoke# set security zones security-zone trust interfaces ge-0/0/3.0user@spoke# set security zones security-zone untrust interfaces ge-0/0/0.0user@spoke# set security zones security-zone vpn interfaces st0.0
  4. Configure the host-inbound services for each zone.

    Details used in this step are the same for both the spoke device (Westford office) and the hub device (Corporate office).

    user@spoke# set security zones security-zone trust host-inbound-traffic system-services alluser@spoke# set security zones security-zone untrust host-inbound-traffic system-services ike
  5. Configure the address book entries for each zone.

    In this example we are using address-book object names such as local-net, sunnyvale-net, and westford-net.

    You can add the additional spoke devices by:

    • Creating an additional address book entry for each spokes’ local LAN
    • Creating a single address book entry that encompasses all spokes’ local LANs
    user@spoke# set security zones security-zone trust address-book address local-net 192.168.178.0/24user@spoke# set security zones security-zone vpn address-book address corp-net 10.10.10.0/24user@spoke# set security zones security-zone vpn address-book address sunnyvale-net 192.168.168.0/24
  6. Configure the IKE policy for main mode, predefined standard proposal set, and preshared key.

    Note: Details (proposal set and preshared key) used in this step are the same for both the spoke device (Westford office) and the hub device (Corporate office).

    user@spoke# set security ike policy ike-policy1 mode mainuser@spoke# set security ike policy ike-policy1 proposal-set standarduser@spoke# set security ike policy ike-policy1 pre-shared-key ascii-text "secretkey"
  7. Configure the spoke IKE gateways (Phase 1) with a peer IP address, an IKE policy, and an outgoing interface.

    Details used in this step are the same for both the spoke device (Westford office) and the hub device (Corporate office), except as follows:

    • The external interface for the spoke device is ge-0/0/0.0.
    • The peer address in the spoke device is the IP address of the hub device.
    user@spoke# set security ike gateway corp-gate address 1.1.1.2user@spoke# set security ike gateway corp-gate ike-policy ike-policy1user@spoke# set security ike gateway corp-gate external-interface ge-0/0/0.0
  8. Configure the IPsec policy for the standard proposal set.

    Note: Details used in this step are the same for the both the spoke device (Westford office) and the hub device (Corporate office).

    user@spoke# set security ipsec policy vpn-policy1 proposal-set standarduser@spoke# set security ipsec policy vpn-policy1 perfect-forward-secrecy keys group2
  9. Configure the IPsec VPN with an IKE gateway and IPsec policy, and bind them to the same st0 interface.

    Note: Details used in this step are the same for both the spoke device (Westford office) and the hub device (Corporate office).

    user@spoke# set security ipsec vpn corp-vpn ike gateway corp-gateuser@spoke# set security ipsec vpn corp-vpn ike ipsec-policy vpn-policy1user@spoke# set security ipsec vpn corp-vpn bind-interface st0.0
  10. Configure bidirectional security policies for tunnel traffic.

    Note: Details used in this step are the same for both the spoke device (Westford office) and the hub device (Corporate office), except that the remote subnets used in the hub device local LAN and in the other spoke device local LAN are different.

    [Edit]user@spoke# edit security policies from-zone trust to-zone vpnedit security policies from-zone trust to-zone vpnuser@spoke# set policy to-corp match source-address local-netuser@spoke# set policy to-corp match destination-address corp-netuser@spoke# set policy to-corp match destination-address sunnyvale-netuser@spoke# set policy to-corp match application anyuser@spoke# set policy to-corp then permit[Edit]user@spoke# edit security policies from-zone vpn to-zone trustedit security policies from-zone vpn to-zone trustuser@spoke# set policy from-corp match source-address corp-netuser@spoke# set policy from-corp match source-address sunnyvale-netuser@spoke# set policy from-corp match destination-address local-netuser@spoke# set policy from-corp match application anyuser@spoke# set policy from-corp then permit
  11. Configure a security policy for Internet traffic.

    Note: Details used in this step are the same for both the spoke device (Westford office) and the hub device (Corporate office).

    user@spoke# edit security policies from-zone trust to-zone untrustuser@spoke# set policy any-permit match source-address anyuser@spoke# set policy any-permit match destination-address anyuser@spoke# set policy any-permit match application anyuser@spoke# set policy any-permit then permit source-nat interface
  12. Configure the TCP MSS to eliminate the fragmentation of TCP traffic across the tunnel.

    Note: Details used in this step are the same for both the spoke device (Westford office) and the hub device (Corporate office).

    user@CORPORATE# set security flow tcp-mss ipsec-vpn mss 1350

Example: SSG Device Sample Configuration (For Reference Only)

Step-by-Step Procedure

  1. This step provides information on SSG device configuration. Because the focus of this example is on Junos OS configuration and troubleshooting, the SSG device configuration is explained briefly.

    To show the configuration settings in Figure 2, a sample of the relevant configurations is provided for an SSG5 device, strictly for reference.

    However, the concepts for configuring policy-based VPNs for Juniper Networks Firewall/VPN products are available in the Concepts and Examples (C&E) guides.

    For more information, see the Concepts & Examples ScreenOS Reference Guide available at http://www.juniper.net/techpubs/software/screenos/ .

    user@SSG5# set zone name "VPN"user@SSG5# set interface ethernet0/6 zone "Trust"user@SSG5# set interface ethernet0/0 zone "Untrust"user@SSG5# set interface "tunnel.1" zone "VPN"user@SSG5# set interface ethernet0/6 ip 192.168.168.1/24user@SSG5# set interface ethernet0/6 routeuser@SSG5# set interface ethernet0/0 ip 2.2.2.2/30user@SSG5# set interface ethernet0/0 routeuser@SSG5# set interface tunnel.1 ip 10.11.11.11/24user@SSG5# set flow tcp-mss 1350user@SSG5# set address "Trust" "sunnyvale-net" 192.168.168.0 255.255.255.0user@SSG5# set address "VPN" "corp-net" 10.10.10.0 255.255.255.0user@SSG5# set address "VPN" "westford-net" 192.168.178.0 255.255.255.0user@SSG5# set ike gateway "corp-ike" address 1.1.1.2 Main outgoing-interface ethernet0/0 preshare "secretkey" sec-level standarduser@SSG5# set vpn "corp-vpn" gateway "corp-ike" replay tunnel idletime 0 sec-level standarduser@SSG5# set vpn "corp-vpn" bind interface tunnel.1user@SSG5# set policy id 1 from "Trust" to "Untrust" "ANY" "ANY" "ANY" nat src permituser@SSG5# set policy id 2 from "Trust" to "VPN" "sunnyvale-net" "corp-net" "ANY" permituser@SSG5# set policy id 2user@SSG5# set dst-address "westford-net"exituser@SSG5# set policy id 3 from "VPN" to "Trust" "corp-net" "sunnyvale-net" "ANY" permituser@SSG5# set policy id 3user@SSG5# set src-address "westford-net"exituser@SSG5# set route 10.10.10.0/24 interface tunnel.1user@SSG5# set route 192.168.178.0/24 interface tunnel.1user@SSG5# set route 0.0.0.0/0 interface ethernet0/0 gateway 2.2.2.1

Verification

This topic includes the following sections:

Confirm VPN Status

Purpose

Confirm VPN status by checking the status of any IKE Phase 1 security associations.

Action

Use the following command on the hub device (in the Corporate office)


user@host> show security ike security-associations
Index Remote Address State Initiator cookie Responder cookie Mode
6 3.3.3.2 UP 94906ae2263bbd8e 1c35e4c3fc54d6d3 Main
7 2.2.2.2 UP 7e7a1c0367dfe73c f284221c656a5fbc Main

Meaning

The output indicates that:

Get Peer Device’s Individual Index Numbers

Purpose

Get details on the individual index numbers of the remote peer devices (spokes).

The Index number value is unique for each IKE SA for every remote peer.

Action


user@corporate> show security ike security-associations index 6 detail
IKE peer 3.3.3.2, Index 6,
Role: Responder, State: UP
Initiator cookie: 94906ae2263bbd8e, Responder cookie: 1c35e4c3fc54d6d3
Exchange type: Main, Authentication method: Pre-shared-keys
Local: 1.1.1.2:500, Remote: 3.3.3.2:500
Lifetime: Expires in 3571 seconds
Algorithms:
Authentication : sha1
Encryption : 3des-cbc
Pseudo random function: hmac-sha1
Traffic statistics:
Input bytes : 1128
Output bytes : 988
Input packets: 6
Output packets: 5
Flags: Caller notification sent
IPsec security associations: 1 created, 0 deleted
Phase 2 negotiations in progress: 1
Negotiation type: Quick mode, Role: Responder, Message ID: 1350777248
Local: 1.1.1.2:500, Remote: 3.3.3.2:500
Local identity: ipv4_subnet(any:0,[0..7]=0.0.0.0/0)
Remote identity: ipv4_subnet(any:0,[0..7]=0.0.0.0/0)
Flags: Caller notification sent, Waiting for done

Meaning

The output displays the details of the spoke (in the Westford office) SA, such as the index, role (initiator or responder), status, exchange type, authentication method, encryption algorithms, traffic statistics, Phase 2 negotiation status, and so on.

You can use the output data to:

View IPsec (Phase 2) Security Associations

Purpose

When IKE Phase 1 is confirmed, view the IPsec (Phase 2) security associations.

Action


user@corporate> show security ipsec security-associations
total configured sa: 2
ID Gateway Port Algorithm SPI Life:sec/kb Mon vsys
<16384 2.2.2.2 500 ESP:3des/sha1 b2fc36f8 3564/ unlim - 0
>16384 2.2.2.2 500 ESP:3des/sha1 5d73929e 3564/ unlim - 0
total configured sa: 2
ID Gateway Port Algorithm SPI Life:sec/kb Mon vsys
<16385 3.3.3.2 500 ESP:3des/sha1 70f789c6 28756/unlim - 0
>16385 3.3.3.2 500 ESP:3des/sha1 80f4126d 28756/unlim - 0

Meaning

The output indicates that:

Display IPsec Security Association Details

Purpose

Display the individual IPsec SA details identified by the index number for a remote peer device (Westford office).

The index value is unique for each IPsec SA. You can view more details for a particular SA by specifying the index value.

Action


user@corporate> show security ipsec security-associations index 16385 detail
Virtual-system: Root
Local Gateway: 1.1.1.2, Remote Gateway: 3.3.3.2
Local Identity: ipv4_subnet(any:0,[0..7]=0.0.0.0/0)
Remote Identity: ipv4_subnet(any:0,[0..7]=0.0.0.0/0)
DF-bit: clear
Direction: inbound, SPI: 1895270854, AUX-SPI: 0
Hard lifetime: Expires in 28729 seconds
Lifesize Remaining: Unlimited
Soft lifetime: Expires in 28136 seconds
Mode: tunnel, Type: dynamic, State: installed, VPN Monitoring: -
Protocol: ESP, Authentication: hmac-sha1-96, Encryption: 3des-cbc
Anti-replay service: enabled, Replay window size: 32
Direction: outbound, SPI: 2163479149, AUX-SPI: 0
Hard lifetime: Expires in 28729 seconds
Lifesize Remaining: Unlimited
Soft lifetime: Expires in 28136 seconds
Mode: tunnel, Type: dynamic, State: installed, VPN Monitoring: -
Protocol: ESP, Authentication: hmac-sha1-96, Encryption: 3des-cbc
Anti-replay service: enabled, Replay window size: 32

Meaning

The output displays the local identity and the remote identity.

Note that a proxy ID mismatch may cause Phase 2 completion to fail. If no IPsec SA is listed, then confirm that the Phase 2 proposals, including the proxy ID settings, are correct for both peers. In this example, for route-based VPNs, the default proxy ID is local=0.0.0.0/0, remote=0.0.0.0/0, service=any.

Note:

  • You might have to specify unique proxy IDs for each IPsec SA if you use multiple route-based VPNs from the same peer server’s IP address.
  • You might have to manually enter the proxy ID to match if you are using applications from some third-party vendors.
  • You must specify st0 interface binding; otherwise, Phase 2 might fail to complete.

Note: If IPsec fails to complete, then check the kmd log or set traceoptions. For more information, see Troubleshooting Hub-and-Spoke VPNs.

Confirm Next-Hop Tunnel Bindings

Purpose

After Phase 2 is complete for all peers, the next step to ensure that the routing is working properly, is to confirm that the NHTB table is established correctly.

To show the NHTB table, run the following command:

Action


user@corporate> show security ipsec next-hop-tunnels
Next-hop gateway interface IPsec VPN name Flag

10.11.11.11 st0.0 sunnyvale-vpn Static
10.11.11.12 st0.0 westford-vpn Auto

Meaning

As in the network topology diagram in Figure 2, the next-hop gateways are the IP addresses for the st0 interfaces of all remote spoke peers. The next hop should be associated with the correct IPsec VPN name. Without an NHTB entry, it is not possible for the hub device to differentiate which IPsec VPN is associated with which next hop.

The flag can have one of the following options:

In this example, the NHTB table is not available on any of the devices in the spoke sites. This is because, from the spoke point of view, the st0 interface is still a point-to-point link with only one IPsec VPN binding. Thus, if you use the show security ipsec next-hop-tunnels command on any of the devices in the spoke site (Westford office), you will not obtain any output.

Confirm Static Routes for Remote Peer Local LANs

Purpose

For the NHTB table to be used, the static route needs to refer to the peer-devices (spoke) st0 interface IP address. You can confirm the route to the remote peer by using the show route <dest-ip-prefix> operational command.

Action


user@corporate> show route 192.168.168.10
inet.0: 9 destinations, 9 routes (9 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
192.168.168.0/24 *[Static/5] 00:08:33
> to 10.11.11.11 via st0.0

user@corporate> show route 192.168.178.10
 
inet.0: 9 destinations, 9 routes (9 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
192.168.178.0/24 *[Static/5] 00:04:04
> to 10.11.11.12 via st0.0

Meaning

In the output, the next hop is the remote peer st0 interfaces’ IP addresses and both routes point to st0.0 as the outgoing interface.

Check Statistics and Errors for an IPsec SA

Purpose

Check statistics and errors for an IPsec SA.

For troubleshooting purpose, check the Encapsulating Security Payload/Authentication Header (ESP/AH) counters for any errors with a particular IPsec SA.

Action


user@corporate> show security ipsec statistics index 16385
ESP Statistics:
Encrypted bytes: 920
Decrypted bytes: 6208
Encrypted packets: 5
Decrypted packets: 87
AH Statistics:
Input bytes: 0
Output bytes: 0
Input packets: 0
Output packets: 0
Errors:
AH authentication failures: 0, Replay errors: 0
ESP authentication failures: 0, ESP decryption failures: 0
Bad headers: 0, Bad trailers: 0

Meaning

An error value of zero in the output indicates a normal condition.

We recommend running this command multiple times to observe any packet loss issues across a VPN. Output from this command also includes the statistics for encrypted and decrypted packet counters, error counters, and so on. You must enable security flow traceoptions to investigate which ESP packets are experiencing errors and why. For more information, see Troubleshooting Hub-and-Spoke VPNs.

Test Traffic Flow Across the VPN

Purpose

Test traffic flow across the VPN after IKE Phase 1, Phase 2, routes, and NHTB entries have completed successfully. You can test traffic flow by using the ping command. You can ping from local host to remote host. You can also initiate pings from the Junos device itself.

This example shows how to initiate a ping request from the Junos device to the remote host at the Sunnyvale office. You can use the same procedure to ping a host device at the Westford office to confirm connectivity. Note that when pings are initiated from the Junos device, the source interface must be specified to ensure that the correct route lookup takes place and that the appropriate zones are referenced in the policy lookup.

In this example, the ge-0/0/0.0 interface resides in the same security zone as the local host and must be specified in the ping request so that the policy lookup can be from zone trust to zone untrust.

Action


user@CORPORATE> ping 192.168.168.10 interface ge-0/0/0 count 5
PING 192.168.168.10 (192.168.168.10): 56 data bytes
64 bytes from 192.168.168.10: icmp_seq=0 ttl=127 time=8.287 ms
64 bytes from 192.168.168.10: icmp_seq=1 ttl=127 time=4.119 ms
64 bytes from 192.168.168.10: icmp_seq=2 ttl=127 time=5.399 ms
64 bytes from 192.168.168.10: icmp_seq=3 ttl=127 time=4.361 ms
64 bytes from 192.168.168.10: icmp_seq=4 ttl=127 time=5.137 ms
--- 192.168.168.10 ping statistics ---
5 packets transmitted, 5 packets received, 0% packet loss
round-trip min/avg/max/stddev = 4.119/5.461/8.287/1.490 ms

Confirm the Connectivity

Purpose

Confirm the connectivity between a remote host and a local host.

Action

ssg5-> ping 10.10.10.10 from ethernet0/6
Type escape sequence to abort
Sending 5, 100-byte ICMP Echos to 10.10.10.10, timeout is 1 seconds from ethernet0/6
!!!!!
Success Rate is 100 percent (5/5), round-trip time min/avg/max=4/4/5 ms
ssg5-> ping 192.168.178.10 from ethernet0/6
Type escape sequence to abort
Sending 5, 100-byte ICMP Echos to 192.168.178.10, timeout is 1 seconds from ethernet0/6
!!!!!
Success Rate is 100 percent (5/5), round-trip time min/avg/max=8/8/10 ms

Meaning

You can confirm end-to-end connectivity from a remote host at a spoke site to a local host at the Corporate office LAN by using the ping command. In this example, the command is initiated from the SSG5 device.

Failed end-to-end connectivity may indicate an issue with routing, policy, end host, or encryption/decryption of the ESP packets. To verify the exact causes of the failure:

Troubleshooting Hub-and-Spoke VPNs

The basic troubleshooting steps are as follows:

The common approach to begin troubleshooting is to start with the lowest layer of the Open Systems Interconnection (OSI) layers and working your way up the OSI stack to determine in which layer the failure occurs. The steps for troubleshooting are as follows:

Junos OS includes the traceoptions feature. Using this feature, you can enable a traceoption flag to write the data from the trace to a log file. The log file may be predetermined, or manually configured and the file is stored in flash memory. These trace logs can be retained even after a system reboot. Check the available flash storage before implementing traceoptions.

You can enable the traceoptions feature in configuration mode and commit the configuration to use the traceoptions feature. Similarly, to disable traceoptions, you must deactivate traceoptions in configuration mode and commit the configuration.

If the VPN is not in the UP state then there is very little reason to test any transit traffic across the VPN. Likewise if Phase 1 is not successful, then there is no need to look at Phase 2 issues.

Check the Free Disk Space on Your Device

Problem

You need to check the statistics on the free disk space in your device file systems to make sure that you have enough memory available to perform other tasks.

Solution

Use show system storage command output to verify the free disk space.


user@corporate> show system storage
Filesystem Size Used Avail Capacity Mounted on
/dev/ad0s1a 213M 136M 75M 65% /
devfs 1.0K 1.0K 0B 100% /dev
devfs 1.0K 1.0K 0B 100% /dev/
/dev/md0 144M 144M 0B 100% /junos
/cf 213M 136M 75M 65% /junos/cf
devfs 1.0K 1.0K 0B 100% /junos/dev/
procfs 4.0K 4.0K 0B 100% /proc
/dev/bo0s1e 24M 13K 24M 0% /config
/dev/md1 168M 7.3M 147M 5% /mfs
/dev/md2 58M 38K 53M 0% /jail/tmp
/dev/md3 7.7M 108K 7.0M 1% /jail/var
devfs 1.0K 1.0K 0B 100% /jail/dev
/dev/md4 1.9M 6.0K 1.7M 0% /jail/html/oem

The /dev/ad0s1a represents the onboard flash memory and is currently at 65% capacity.

Note: You can view the available system storage in the J-Web interface under the System Storage option.

Note: You can enable traceoptions to log the trace data to the filenames specified or to the default log file to receive the output of the tracing operation. The output of the traceoptions is placed in /var/log/kmd.

Check the Log Files to Verify Different Scenarios and to Upload Log Files to an FTP Server

Problem

You need to the check the log files to verify that logging to the syslog is working and that there are no errors shown in the security IKE debug messages and security flow debug messages.

Solution

To verify the messages in the syslog, use the show log kmd, show log security-trace, and show log messages commands.

user@corporate> show log kmduser@corporate> show log security-traceuser@corporate> show log messages

Note: You can view a list of all logs in the /var/log directory by using the show log command.

Log files can also be uploaded to an FTP server by using the file copy command.

(operational mode):


user@corporate> file copy /var/log/kmd ftp://10.10.10.10/kmd.log
ftp://10.10.10.10/kmd.log 100% of 35 kB 12 MBps

Enable IKE Traceoptions to View Messages on IKE

Problem

You need to view additional details Phase 1 and Phase 2 negotiation issues and error messages for by enabling IKE and PKI traceoptions.

To verify success or failure messages for IKE or IPsec, you can view the key management process (kmd) log by using the show log kmd command. Because the kmd log displays some general messages, it may be useful to obtain additional details by enabling IKE and PKI traceoptions.

Note: Generally, it is best practice to troubleshoot the peer that has the responder role. You must obtain the trace output from the initiator and the responder to understand the cause of a failure.

Solution

You can enable IKE traceoptions by configuring the file to write trace options and setting the flag for trace messages in edit security ike traceoptions hierarchy.

user@corporate> configureEntering configuration mode[edit]user@corporate> edit security ike traceoptions[edit security ike traceoptions]

user@corporate# set file ?
Possible completions:
<filename> Name of file in which to write trace information
files Maximum number of trace files (2..1000)
match Regular expression for lines to be logged
no-world-readable Don't allow any user to read the log file
size Maximum trace file size (10240..1073741824)
world-readable Allow any user to read the log file
[edit][edit security ike traceoptions]

user@corporate# set flag ? 
Possible completions:
all Trace everything
certificates Trace certificate events
database Trace security associations database events
general Trace general events
ike Trace IKE module processing
parse Trace configuration processing
policy-manager Trace policy manager processing
routing-socket Trace routing socket messages
timer Trace internal timer events

Note: If you do not specify file names for the <filename> field, then all IKE traceoptions are written to the kmd log.

To write trace data to the log, you must specify at least one flag option. For example:

Setting Up IKE Traceoptions to Troubleshoot IKE-Related Issues

Problem

You need to configure the recommended settings for IKE traceoptions, such as file size, policy-manager, flag, and routing-socket.

Solution

You can configure the required IKE traceoptions in the edit security ike traceoptions hierarchy by using the following commands:

user@corporate# edit security ike traceoptions[edit security ike traceoptions]user@corporate# set file size 1muser@corporate# set flag policy-manageruser@corporate# set flag ikeuser@corporate# set flag routing-socketuser@corporate# commit

Analyzing the Phase 1 and Phase 2 Success Messages

Problem

Confirm the success of Phase 1 and Phase 2.

Solution

Use the show log kmd command output to confirm that IKE Phase 1 and Phase 2 conditions are successful, as shown below:

Oct 8 10:41:40 Phase-1 [responder] done for local=ipv4(udp:500,[0..3]=1.1.1.2)
remote=ipv4(udp:500,[0..3]=2.2.2.2)
Oct 8 10:41:51 Phase-2 [responder] done for p1_local=ipv4(udp:500,[0..3]=1.1.1.2)
p1_remote=ipv4(udp:500,[0..3]=2.2.2.2) p2_local=ipv4_subnet(any:0,[0..7]=10.10.10.0/24)
p2_remote=ipv4_subnet(any:0,[0..7]=192.168.168.0/24)

The sample output indicates:

You can also confirm the IPsec SA status by using the verification commands mentioned in Display IPsec Security Association Details.

Analyzing the Phase 1 Failure Message (Proposal Mismatch)

Problem

Phase 1 (responder) fails with an error because of proposal mismatch.

Solution

To resolve this issue, ensure that the parameters for the Phase 1 proposals match on both the responder and the initiator.

The following sample shows output from the show log kmd command, where the IKE Phase 1 condition is a failure caused by mismatched proposal:

Oct 8 10:31:10 Phase-1 [responder] failed with error(No proposal chosen) for
local=unknown(any:0,[0..0]=) remote=ipv4(any:0,[0..3]=2.2.2.2)

Oct 8 10:31:10 1.1.1.2:500 (Responder) <-> 2.2.2.2:500 { 011359c9 ddef501d - 2216ed2a bfc50f5f [-
1] / 0x00000000 } IP; Error = No proposal chosen (14)

The sample output indicates:

Analyzing the Phase 1 Failure Message (Policy Lookup Failure)

Problem

Phase 1 (responder) fails with error caused by a policy lookup failure.

This condition indicates that Phase 1 is failing because of a proposal mismatch and because the responder is not recognizing the incoming request as originating from a valid gateway peer. The peer was not recognized because of an incorrect peer address, a mismatched peer ID type, or an incorrect peer ID, depending on whether this is a dynamic VPN or a static VPN.

Solution

To resolve this issue, configure the following before Phase 1:

The following sample shows the output from the show log kmd command, where the Phase 1 failure is caused by a policy lookup failure:

Oct 8 10:39:40 Unable to find phase-1 policy as remote peer:2.2.2.2 is not recognized.

Oct 8 10:39:40 KMD_PM_P1_POLICY_LOOKUP_FAILURE: Policy lookup for Phase-1 [responder] failed for
p1_local=ipv4(any:0,[0..3]=1.1.1.2) p1_remote=ipv4(any:0,[0..3]=2.2.2.2)
Oct 8 10:39:40 1.1.1.2:500 (Responder) <-> 2.2.2.2:500 { 18983055 dbe1d0af - a4d6d829 f9ed3bba [-
1] / 0x00000000 } IP; Error = No proposal chosen (14)

The sample output indicates:

Analyzing the Phase 1 Failure Message (Invalid Payload Type)

Problem

Phase 1 (responder) fails because of an invalid payload type. The invalid payload type indicates a problem with IKE packet decryption caused by mismatch of the preshared keys.

Solution

To resolve this issue, configure the preshared keys to match on the peers.

The following sample shows the output from the show log kmd command, when the Phase 1 condition is a failure caused by invalid payload type:

Oct 8 10:36:20 1.1.1.2:500 (Responder) <-> 2.2.2.2:500 { e9211eb9 b59d543c - 766a826d bd1d5ca1 [-
1] / 0x00000000 } IP; Invalid next payload type = 17
Oct 8 10:36:20 phase-1 [responder] failed with error(Invalid payload type) for
local=unknown(any:0,[0..0]=) remote=ipv4(any:0,[0..3]=2.2.2.2)

The sample output indicates:

Analyzing the Phase 2 Failure Message (Proposal Mismatch)

Problem

Phase 2 fails with error caused by proposal mismatch between two peers.

Solution

To resolve this issue, configure the Phase 2 proposals to match on the peers.

The following sample shows output of the show log kmd command, when the Phase 2 condition is a failure:

Oct 8 10:53:34 Phase-1 [responder] done for local=ipv4(udp:500,[0..3]=1.1.1.2)
remote=ipv4(udp:500,[0..3]=2.2.2.2)
Oct 8 10:53:34 1.1.1.2:500 (Responder) <-> 2.2.2.2:500 { cd9dff36 4888d398 - 6b0d3933 f0bc8e26 [0]
/ 0x1747248b } QM; Error = No proposal chosen (14)

The sample output indicates:

Analyzing the Phase 2 Failure Message (Proxy ID Mismatch)

Problem

Phase 2 fails with error caused by proxy ID mismatch between two peers, resulting from a mismatch of configurations on the local peer.

Solution

To resolve this issue, configure the proxy ID on one of the peers so that it matches the other peer.

The following sample shows output from the show log kmd command, when the Phase 2 condition is a failure.

Oct 8 10:56:00 Phase-1 [responder] done for local=ipv4(udp:500,[0..3]=1.1.1.2)
remote=ipv4(udp:500,[0..3]=2.2.2.2)
Oct 8 10:56:00 Failed to match the peer proxy ids
p2_remote=ipv4_subnet(any:0,[0..7]=192.168.168.0/24)
p2_local=ipv4_subnet(any:0,[0..7]=10.10.20.0/24)
 for the remote peer:ipv4(udp:500,[0..3]=2.2.2.2)
Oct 8 10:56:00 KMD_PM_P2_POLICY_LOOKUP_FAILURE: Policy lookup for Phase-2 [responder] failed for
p1_local=ipv4(udp:500,[0..3]=1.1.1.2) p1_remote=ipv4(udp:500,[0..3]=2.2.2.2)
p2_local=ipv4_subnet(any:0,[0..7]=10.10.20.0/24)
p2_remote=ipv4_subnet(any:0,[0..7]=192.168.168.0/24)
Oct 8 10:56:00 1.1.1.2:500 (Responder) <-> 2.2.2.2:500 { 41f638eb cc22bbfe - 43fd0e85 b4f619d5 [0]
/ 0xc77fafcf } QM; Error = No proposal chosen (14)

The sample output indicates:

Common Problems Related to IKE and PKI

Problem

Troubleshoot common problems related to IKE and PKI.

Solution

Enabling the traceoptions feature helps you to gather more information for debugging issues than is obtainable from the normal log entries. You can use the traceoptions log to understand the reasons for traffic not passing through the tunnel because of problems related to route lookup, security policy, or some other flow issue (assuming that the IPsec tunnel is up).

Details of flow traceoption output are beyond the scope of this example. For more information on traceoptions output, see the Junos Enhanced Services Route-Based VPN Configuration and Troubleshooting at http://kb.juniper.net/kb/documents/public/junos_es/Junos_ES_Route_based_VPN_to_ScreenOS.pdf.

Note: Enabling the flow traceoptions increases the device resource usage, and it should always be best avoided during peak traffic load times or when CPU usage is very high.

We recommend enabling packet filters to reduce the resource usage and to facilitate classification of the required packets.

Note: We recommend deleting or deactivating all flow traceoptions and removing any unnecessary log files from flash memory after completing troubleshooting. To disable traceoptions, you must deactivate traceoptions in configuration mode and then commit the configuration.

Enable Flow Traceoption to View Messages on Routing or Policy Issues

Problem

View the log messages on routing- or policy-related issues.

Solution

You need to the check the log files to verify that logging to the syslog is working and that there are no errors in the security IKE debug messages or the security flow debug messages.

user@corporate# edit security flow traceoptions[edit security flow traceoptions]

user@corporate# set file ?
Possible completions:
<filename> Name of file in which to write trace information
files Maximum number of trace files (2..1000)
match Regular expression for lines to be logged
no-world-readable Don't allow any user to read the log file
size Maximum trace file size (10240..1073741824)
world-readable Allow any user to read the log file
[edit security flow traceoptions]

user@corporate# set flag ?
Possible completions:
ager Ager events
all All events
basic-datapath Basic packet flow
cli CLI configuration and commands changes
errors Flow errors
fragmentation Ip fragmentation and reassembly events
high-availability Flow high-availability information
host-traffic Flow host-traffic information
lookup Flow lookup events
multicast Multicast flow information
packet-drops Packet drops
route Route information
session Session creation and deletion events
session-scan Session scan information
tcp-advanced Advanced TCP packet flow
tcp-basic TCP packet flow
tunnel Tunnel information

Note: If you do not specify filenames for the filename field, then all flow traceoptions are written to the security-trace log. However, you can specify a different filename, if desired.

To write data to the log, you must specify at least one flag option. For example:

Configure Packet Filters to Reduce the Resource Usage

Problem

Limit the scope of the traffic to be captured by the flow traceoptions.

Solution

You can limit the scope of traffic captured by configuring packet filters as shown in the following command.

[edit security flow traceoptions]

user@corporate# set packet-filter filter-name ?
Possible completions:
+ apply-groups Groups from which to inherit configuration data
+ apply-groups-except Don't inherit configuration data from these groups
destination-port Match TCP/UDP destination port
destination-prefix Destination IPv4 address prefix
interface Logical interface
protocol Match IP protocol type
source-port Match TCP/UDP source port
source-prefix Source IPv4 address prefix

Note: Note the following points concerning the packet-filter:

  • By configuring the packet-filter option, you can filter the output based on source or destination IP, source or destination port, interface, and IP protocol.
  • You can configure up to 64 filters.
  • A packet filter can work in reverse direction to capture the reply traffic, if the source of the original packet matches the filter. For more information on flow packet-filter options, see Troubleshoot the Traffic, Using Traceoptions with Packet Filters . Terms listed within the same packet filter act as a Boolean logical AND statement. That means that all statements within the packet filter need to match in order to write the output to the log. A listing of multiple filter names acts as a logical OR.

Troubleshoot the Traffic, Using Traceoptions with Packet Filters

Problem

Troubleshoot the traffic flow from the remote peer (Westford Office) to the local host (Corporate Office).

Solution

You can troubleshoot the traffic flow between the remote peer to the local host by using packet filters. You can use the output details from each flow traceoption command (as shown in Table 2) to analyze the traffic.

user@corporate# edit security flow traceoptions[edit security flow traceoptions]user@corporate# set file size 1m files 3user@corporate# set flag basic-datapathuser@corporate# set packet-filter remote-to-local source-prefix 192.168.178.0/24user@corporate# set packet-filter remote-to-local destination-prefix 10.10.10.0/24user@corporate# set packet-filter local-to-remote source-prefix 10.10.10.0/24user@corporate# set packet-filter local-to-remote destination-prefix 192.168.178.0/24user@corporate# set packet-filter remote-esp protocol 50user@corporate# set packet-filter remote-esp source-prefix 3.3.3.2/32user@corporate# commit

Table 2 provides output details for each flow traceoption setting in this sample configuration.

Table 2: Output Details for Flow Traceoption Setting

Output of the Settings

What it indicates...

[edit security flow traceoptions]user@CORPORATE# showfile flow-trace-log size 1m files 3;flag basic-datapath;
  • Because there are no filename is specified, all flow traceoptions are written to the security-trace log file.
  • The security-trace log file is set to 1 MB and up to 3 files can be created. Because the flow traceoption may generate a large log file to capture the traffic, a single file may not be adequate.
  • Flag basic-datapath captures the details for most flow-related problems.
packet-filter remote-to-local {source-prefix 192.168.168.0/24;destination-prefix 10.10.10.0/24;}
  • The packet-filter remote-to-local is set for capturing the decapsulated or unencrypted traffic from the remote peer to the local host.
  • The filter acts as a Boolean logical AND statement because there are multiple terms listed. This filter captures the packets only if the source IP address and destination IP address match. If one of the addresses does not match, then the packet is not captured.
  • The packet filters are bidirectional, and it is not necessary to configure a filter for the reply traffic.
packet-filter local-to-remote {source-prefix 10.10.10.0/24;destination-prefix 192.168.178.0/24;}

The packet-filter local-to-remote is required even though it is not required to set a filter for capturing the reply traffic. However a filter can capture only the packets that are originally sourced from the specified side. Thus, the local-to-remote filter in this example may still be required to capture traffic from the local side to the remote side.

packet-filter remote-esp {protocol 50;source-prefix 3.3.3.2/32;}
  • The packet-filter remote-esp is optional and depends on whether or not the previous filter could capture any packets.
  • This filter can capture all ESP (IP protocol 50) or encrypted packets from remote peer 2.2.2.2.

    Note: Because this filter is configured at the bottom of the hierarchy, it captures all encrypted traffic from server 2.2.2.2, which may not be required.

    Note: However, the last filter can capture all encrypted traffic from 2.2.2.2 including packets are not required. Since the last filter captures unencrypted traffic, this filter may not be required.

Thus, using the filters, you can troubleshoot any traffic flow issues to and from the Corporate Office and the Westford site. Additional filters can be configured for troubleshooting from Westford to Sunnyvale and vice versa. In addition, to help narrow the scope, a single host can be specified with the /32 mask to avoid having too much data written to the trace log. Finally, as always, if any assistance is needed in interpreting the data from any of the traceoption logs, contact your regional JTAC (Juniper Technical Assistance Center). The JTAC website can be found at: http://www.juniper.net/customers/support/ .

Related Topics

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