Network Diagram
ER-X
- eth0 (WAN) – 203.0.113.1
- eth1 (LAN) – 192.168.1.1/24
Juniper SRX
- ge-0/0/0 (WAN) – 192.0.2.1
- ge-0/0/1 (LAN) – 172.16.1.1/24
Steps: Policy-Based VPN
For the purpose of this article it is assumed that the routing and interface configuration is already in place and that reachability has been tested.
The UDP ports and protocols relevant to IPsec are:
- UDP 500 (IKE)
- ESP (Protocol 50)
- UDP 4500 (NAT-T)
The type of VPN that will be created is called a Policy-Based VPN which uses remote and local subnets, otherwise known as proxy IDs. These values need to match exactly between the two peers and need to be mirrored images of each other. Only the prefixes defined in the proxy IDs will be carried over the tunnel. In the example ER has the 192.168.1.0/24 present on the LAN side, whereas the Juniper side uses 172.16.1.0/24.
The first part of the configuration focuses on the ER, afterwards the VPN will be set up on the SRX.
1. Enter configuration mode.
configure
2. Exclude IPsec traffic from NAT and allow the automatic creation of the firewall rules.
set vpn ipsec auto-firewall-nat-exclude enable
3. Create the IKE proposal (P1) and Security Associations (SAs).
set vpn ipsec ike-group FOO0 lifetime 86400 set vpn ipsec ike-group FOO0 proposal 1 dh-group 14 set vpn ipsec ike-group FOO0 proposal 1 encryption aes256 set vpn ipsec ike-group FOO0 proposal 1 hash sha256
4. Create the ESP proposal (P2) and Security Associations (SAs).
set vpn ipsec esp-group FOO0 lifetime 43200 set vpn ipsec esp-group FOO0 pfs disable set vpn ipsec esp-group FOO0 proposal 1 encryption aes128 set vpn ipsec esp-group FOO0 proposal 1 hash md5
| Note: The choices for SAs in this example are based on optimizing the VPN for performance, stability and security. The IKE proposal focuses on security (AES256 + SHA256), whereas the ESP proposal focuses on performance (AES128 + MD5). Whatever set of SAs are chosen, make sure that the settings for Phase 1 (P1) and Phase 2 (P2) match on both sides of the connection. |
5. Define the peer address and the pre-shared-key (replace <secret> with your desired passphrase).
set vpn ipsec site-to-site peer 192.0.2.1 authentication mode pre-shared-secret set vpn ipsec site-to-site peer 192.0.2.1 authentication pre-shared-secret <secret> set vpn ipsec site-to-site peer 192.0.2.1 description IPsec
6. Define the local source address (public IP) of the Site-to-Site VPN connection.
set vpn ipsec site-to-site peer 192.0.2.1 local-address 203.0.113.1
| Note: It is also possible to use a non-static IP address for the WAN connection. In the case of DHCP, please use set … peer 192.0.2.1 dhcp-interface eth0. For PPPoE interfaces or load-balancing scenarios it is currently recommend to use set … peer 192.0.2.1 local-address 0.0.0.0 over local-address any. |
7. Link the IKE proposal to the Site-to-Site connection.
set vpn ipsec site-to-site peer 192.0.2.1 ike-group FOO0
8. Create a tunnel that defines the remote and local subnets (proxy IDs) and link the ESP proposal.
set vpn ipsec site-to-site peer 192.0.2.1 tunnel 1 esp-group FOO0 set vpn ipsec site-to-site peer 192.0.2.1 tunnel 1 local prefix 192.168.1.0/24 set vpn ipsec site-to-site peer 192.0.2.1 tunnel 1 remote prefix 172.16.1.0/24
9. (Optional) Enable the IPsec offloading feature to increase ESP (not IKE) performance.
set system offload ipsec enable (this requires a reboot to become active)10. Commit the changes.
commit11. Save the configuration.
save
Steps: Juniper SRX VPN
Please make sure that the latest stable version of Junos is being used and that the device is capable of reaching the internet. The Juniper side of the Site-to-Site VPN connection is based on the following IPsec article: Configuring a Policy-Based VPN
CLI STEPS: Access the Junos command line interface (CLI). |
1. Enter configuration mode.
configure2. Link the interfaces to the relevant zones and allow IKE (UDP500) on the WAN interface.
set security zones security-zone trust interfaces ge-0/0/1.0 set security zones security-zone untrust interfaces ge-0/0/0.0 set security zones security-zone untrust host-inbound-traffic system-services ike
| Note: In this article unit 0 is used for all relevant interfaces. The zones ‘untrust’ and ‘trust’ are the default zones and do not necessarily match other environments. |
3. Define the local and remote subnets as address ranges in an address book.
set security address-book global address remote 192.168.1.0/24 set security address-book global address local 172.16.1.0/24
4. Allow the IPsec traffic between the ‘untrust’ and ‘trust’ zones and link the address books.
set security policies from-zone trust to-zone untrust policy trust-to-ipsec match source-address local set security policies from-zone trust to-zone untrust policy trust-to-ipsec match destination-address remote set security policies from-zone trust to-zone untrust policy trust-to-ipsec match application any set security policies from-zone trust to-zone untrust policy trust-to-ipsec then permit tunnel ipsec-vpn IPsec set security policies from-zone trust to-zone untrust policy trust-to-ipsec then permit tunnel pair-policy ipsec-to-trust set security policies from-zone untrust to-zone trust policy ipsec-to-trust match source-address remote set security policies from-zone untrust to-zone trust policy ipsec-to-trust match destination-address local set security policies from-zone untrust to-zone trust policy ipsec-to-trust match application any set security policies from-zone untrust to-zone trust policy ipsec-to-trust then permit tunnel ipsec-vpn IPsec set security policies from-zone untrust to-zone trust policy ipsec-to-trust then permit tunnel pair-policy trust-to-ipsec
| Note: The tunnel pair-policy statement links the ‘untrust to-zone trust’ to the ‘trust to-zone untrust’ policy and vice versa. These policies basically link the address books to the IPsec tunnel and define the local and remote subnets (proxy IDs). |
5. Make sure that the IPsec traffic policies are matched before the existing policy rules.
insert security policies from-zone trust to-zone untrust policy trust-to-ipsec before policy default-permit insert security policies from-zone untrust to-zone trust policy ipsec-to-trust before policy default-deny
6. Exclude IPsec traffic from being translated in NAT.
set security nat source rule-set sourcenat from zone trust set security nat source rule-set sourcenat to zone untrust set security nat source rule-set sourcenat rule nat match source-address 0.0.0.0/0 set security nat source rule-set sourcenat rule nat match destination-address 0.0.0.0/0 set security nat source rule-set sourcenat rule nat then source-nat interface set security nat source rule-set sourcenat rule ipsec match source-address-name local set security nat source rule-set sourcenat rule ipsec match destination-address-name remote set security nat source rule-set sourcenat rule ipsec then source-nat off
7. Make sure that the IPsec NAT exclusion rule is matched before the existing Source-NAT rule.
insert security nat source rule-set sourcenat rule ipsec before rule nat
| Note: This article assumes that Source-NAT has not already been configured on the device. If the NAT rule already exists, please make sure that the new IPsec rule is placed in front of the existing NAT rule using the insert statement. |
8. Create the IKE proposal (IKEProposal) matching the defined SAs on the EdgeRouter.
set security ike proposal IKEProposal authentication-method pre-shared-keys set security ike proposal IKEProposal dh-group group14 set security ike proposal IKEProposal authentication-algorithm sha-256 set security ike proposal IKEProposal encryption-algorithm aes-256-cbc set security ike proposal IKEProposal lifetime-seconds 86400
9. Create the IKE policy (IKEPolicy) and link it to the IKE proposal (replace <secret> with your desired passphrase).
set security ike policy IKEPolicy mode main set security ike policy IKEPolicy proposals IKEProposal set security ike policy IKEPolicy pre-shared-key ascii-text <secret>
10. Create the IKE gateway (IKEGateway) and link it to the IKE policy.
set security ike gateway IKEGateway ike-policy IKEPolicy set security ike gateway IKEGateway address 203.0.113.1 set security ike gateway IKEGateway external-interface ge-0/0/0 set security ike gateway IKEGateway local-address 192.0.2.1
11. Create the ESP proposal (ESPProposal) matching the defined SAs on the EdgeRouter.
set security ipsec proposal ESPProposal protocol esp set security ipsec proposal ESPProposal authentication-algorithm hmac-md5-96 set security ipsec proposal ESPProposal encryption-algorithm aes-128-cbc set security ipsec proposal ESPProposal lifetime-seconds 43200
12. Create the ESP policy (ESPPolicy) and link it to the ESP proposal.
set security ipsec policy ESPPolicy proposals ESPProposal
13. Create the VPN IPsec connection and link it to the IKE gateway and ESP policy.
set security ipsec vpn IPsec ike gateway IKEGateway set security ipsec vpn IPsec ike ipsec-policy ESPPolicy
14. (Optional) Activate traceoptions for IKE to log messages for troubleshooting purposes.
set security ike traceoptions flag all set security ike traceoptions file ike.log
| Note: If not needed anymore, please make sure that the traceoptions are either deactivated (deactivate security ike traceoptions) or removed from the configuration. |
15. Commit the changes.
commitSteps: Testing & Verification
After configuring the IPsec VPN, verify the connection/state using the following commands.
1. Verify the IPsec Security Associations (SAs) and status on the ER:
show vpn ipsec sa peer-192.0.2.1-tunnel-1: #1, ESTABLISHED, IKEv1, 184447c009d51f80:14cc0f13aff401c0 local '203.0.113.1' @ 203.0.113.1 remote '192.0.2.1' @ 192.0.2.1 AES_CBC-256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_2048 established 237s ago, reauth in 85347s peer-192.0.2.1-tunnel-1: #1, INSTALLED, TUNNEL, ESP:AES_CBC-128/HMAC_MD5_96 installed 237 ago, rekeying in 41939s, expires in 42964s in cb321982, 180 bytes, 3 packets, 231s ago out 5d4174b1, 180 bytes, 3 packets, 231s ago local 192.168.1.0/24 remote 172.16.1.0/24 sudo ipsec statusall Status of IKE charon daemon (strongSwan 5.2.2, Linux 3.10.14-UBNT, mips): uptime: 10 minutes, since Mar 12 09:05:48 2017 malloc: sbrk 376832, mmap 0, used 269320, free 107512 worker threads: 11 of 16 idle, 5/0/0/0 working, job queue: 0/0/0/0, scheduled: 2 Listening IP addresses: 203.0.113.1 192.168.1.1 Connections: peer-192.0.2.1-tunnel-1: 203.0.113.1...192.0.2.1 IKEv1 peer-192.0.2.1-tunnel-1: local: [203.0.113.1] uses pre-shared key authentication peer-192.0.2.1-tunnel-1: remote: [192.0.2.1] uses pre-shared key authentication peer-192.0.2.1-tunnel-1: child: 192.168.1.0/24 === 172.16.1.0/24 TUNNEL Routed Connections: peer-192.0.2.1-tunnel-1{1}: ROUTED, TUNNEL peer-192.0.2.1-tunnel-1{1}: 192.168.1.0/24 === 172.16.1.0/24 Security Associations (1 up, 0 connecting): peer-192.0.2.1-tunnel-1[1]: ESTABLISHED 5 minutes ago, 203.0.113.1[203.0.113.1]...192.0.2.1[192.0.2.1] peer-192.0.2.1-tunnel-1[1]: IKEv1 SPIs: 184447c009d51f80_i* 14cc0f13aff401c0_r, pre-shared key reauthentication in 23 hours peer-192.0.2.1-tunnel-1[1]: IKE proposal: AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_2048 peer-192.0.2.1-tunnel-1{1}: INSTALLED, TUNNEL, ESP SPIs: cb321982_i 5d4174b1_o peer-192.0.2.1-tunnel-1{1}: AES_CBC_128/HMAC_MD5_96, 180 bytes_i (3 pkts, 324s ago), 180 bytes_o (3 pkts, 324s ago) peer-192.0.2.1-tunnel-1{1}: 192.168.1.0/24 === 172.16.1.0/24
2. Verify the ER IPsec strongSwan configuration:
sudo cat /etc/ipsec.conf # generated by /opt/vyatta/sbin/vpn-config.pl config setup conn %default keyexchange=ikev1 conn peer-192.0.2.1-tunnel-1 left=203.0.113.1 right=192.0.2.1 leftsubnet=192.168.1.0/24 rightsubnet=172.16.1.0/24 ike=aes256-sha256-modp2048! keyexchange=ikev1 ikelifetime=86400s esp=aes128-md5! keylife=43200s rekeymargin=540s type=tunnel compress=no authby=secret auto=route keyingtries=%forever #conn peer-192.0.2.1-tunnel-1
3. Capture the arrival of IKE traffic on the ER external WAN interface:
sudo tcpdump -i eth0 -n udp dst port 500 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes IP 203.0.113.1.500 > 192.0.2.1.500: isakmp: phase 1 I ident IP 192.0.2.1.500 > 203.0.113.1.500: isakmp: phase 1 R ident IP 203.0.113.1.500 > 192.0.2.1.500: isakmp: phase 1 I ident[E] IP 192.0.2.1.500 > 203.0.113.1.500: isakmp: phase 1 R ident[E] IP 203.0.113.1.500 > 192.0.2.1.500: isakmp: phase 2/others I oakley-quick[E] IP 192.0.2.1.500 > 203.0.113.1.500: isakmp: phase 2/others R oakley-quick[E]
| Note: This is a live capture. If there is no output that means that the traffic is either not being generated on the client, or there is something blocking the traffic upstream. |
4. Capture the ER IPsec VPN logs:
sudo swanctl --log [KNL] creating acquire job for policy 192.168.1.10/32[icmp/8] === 172.16.1.10/32[icmp/8] with reqid {1} [IKE] initiating Main Mode IKE_SA peer-192.0.2.1-tunnel-1[1] to 192.0.2.1 [ENC] generating ID_PROT request 0 [ SA V V V V ] [NET] sending packet: from 203.0.113.1[500] to 192.0.2.1[500] (160 bytes) [NET] received packet: from 192.0.2.1[500] to 203.0.113.1[500] (108 bytes) [ENC] parsed ID_PROT response 0 [ SA V ] [IKE] received NAT-T (RFC 3947) vendor ID [ENC] generating ID_PROT request 0 [ KE No NAT-D NAT-D ] [ENC] parsed ID_PROT response 0 [ KE No V V V V NAT-D NAT-D ] [ENC] generating ID_PROT request 0 [ ID HASH N(INITIAL_CONTACT) ] [ENC] parsed ID_PROT response 0 [ ID HASH ] [IKE] IKE_SA peer-192.0.2.1-tunnel-1[1] established between 203.0.113.1[203.0.113.1]...192.0.2.1[192.0.2.1] [ENC] generating QUICK_MODE request 561157166 [ HASH SA No ID ID ] [ENC] parsed QUICK_MODE response 561157166 [ HASH SA No ID ID N((24576)) ] [IKE] CHILD_SA peer-192.0.2.1-tunnel-1{1} established with SPIs cb321982_i 5d4174b1_o and TS 192.168.1.0/24 === 172.16.1.0/24
| Note: This is also live capture. If there is no output that means that the traffic is either not being allowed through the firewall. Alternatively you can use the show vpn log | no-more command to view the entire IPsec log history. |
5. Verify the IPsec Security Associations (SAs) and statistics on the SRX:
show security ike sa Index State Initiator cookie Responder cookie Mode Remote Address 697909 UP 9e9c73d889be2378 abbed46436bd025b Main 203.0.113.1 show security ike sa detail IKE peer 203.0.113.1, Index 2264724, Gateway Name: IKEGateway Role: Responder, State: UP Initiator cookie: 091c0d059ea7afbe, Responder cookie: baf3c7ea2c2f5016 Exchange type: Main, Authentication method: Pre-shared-keys Local: 192.0.2.1:500, Remote: 203.0.113.1:500 Lifetime: Expires in 86206 seconds Peer ike-id: 203.0.113.1 Xauth assigned IP: 0.0.0.0 Algorithms: Authentication : hmac-sha256-128 Encryption : aes256-cbc Pseudo random function: hmac-sha256 Diffie-Hellman group : DH-group-14 Traffic statistics: Input bytes : 928 Output bytes : 788 Input packets: 5 Output packets: 4 Flags: IKE SA is created IPSec security associations: 1 created, 0 deleted Phase 2 negotiations in progress: 0 Negotiation type: Quick mode, Role: Responder, Message ID: 0 Local: 192.0.2.1:500, Remote: 203.0.113.1:500 Local identity: 192.0.2.1 Remote identity: 203.0.113.1 Flags: IKE SA is created show security ipsec sa Total active tunnels: 1 ID Algorithm SPI Life:sec/kb Mon lsys Port Gateway <2 ESP:aes-cbc-128/md5 14ce38b 42981/unlim - root 500 203.0.113.1 >2 ESP:aes-cbc-128/md5 cf29ade9 42981/unlim - root 500 203.0.113.1 show security ipsec sa detail ID: 2 Virtual-system: root, VPN Name: IPsec Local Gateway: 192.0.2.1, Remote Gateway: 203.0.113.1 Local Identity: ipv4_subnet(any:0,[0..7]=172.16.1.0/24) Remote Identity: ipv4_subnet(any:0,[0..7]=192.168.1.0/24) Version: IKEv1 DF-bit: clear Policy-name: trust-to-ipsec Port: 500, Nego#: 1, Fail#: 0, Def-Del#: 0 Flag: 0x600829 Last Tunnel Down Reason: SA not initiated Direction: inbound, SPI: 14ce38b, AUX-SPI: 0 , VPN Monitoring: - Hard lifetime: Expires in 42965 seconds Lifesize Remaining: Unlimited Soft lifetime: Expires in 42376 seconds Mode: Tunnel(0 0), Type: dynamic, State: installed Protocol: ESP, Authentication: hmac-md5-96, Encryption: aes-cbc (128 bits) Anti-replay service: counter-based enabled, Replay window size: 64 Direction: outbound, SPI: cf29ade9, AUX-SPI: 0 , VPN Monitoring: - Hard lifetime: Expires in 42965 seconds Lifesize Remaining: Unlimited Soft lifetime: Expires in 42376 seconds Mode: Tunnel(0 0), Type: dynamic, State: installed Protocol: ESP, Authentication: hmac-md5-96, Encryption: aes-cbc (128 bits) Anti-replay service: counter-based enabled, Replay window size: 64 show security ipsec statistics ESP Statistics: Encrypted bytes: 360 Decrypted bytes: 180 Encrypted packets: 3 Decrypted packets: 3 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
6. Verify the security policies on the SRX:
show security policies detail Policy: trust-to-ipsec, action-type: permit, State: enabled, Index: 5, Scope Policy: 0 Policy Type: Configured Sequence number: 1 From zone: trust, To zone: untrust Source addresses: local(global): 172.16.1.0/24 Destination addresses: remote(global): 192.168.1.0/24 Application: any IP protocol: 0, ALG: 0, Inactivity timeout: 0 Source port range: [0-0] Destination port range: [0-0] Per policy TCP Options: SYN check: No, SEQ check: No Tunnel: IPsec, Type: IPSec, Index: 2 Pair policy: ipsec-to-trust Policy: ipsec-to-trust, action-type: permit, State: enabled, Index: 7, Scope Policy: 0 Policy Type: Configured Sequence number: 1 From zone: untrust, To zone: trust Source addresses: remote(global): 192.168.1.0/24 Destination addresses: local(global): 172.16.1.0/24 Application: any IP protocol: 0, ALG: 0, Inactivity timeout: 0 Source port range: [0-0] Destination port range: [0-0] Per policy TCP Options: SYN check: No, SEQ check: No Tunnel: IPsec, Type: IPSec, Index: 2 Pair policy: trust-to-ipsec
7. Analyze the IKE logs (if captured with traceoptions) on the SRX:
file show /var/log/ike.log Successfully added SA Config iked_pm_ike_spd_notify_request: Sending Initial contact ssh_ike_connect: Start, remote_name = 203.0.113.1:500, xchg = 2, flags = 00090000 ike_init_isakmp_sa: Start, remote = 203.0.113.1:500, initiator = 1 ike_find_pre_shared_key: Find pre shared key key for 192.0.2.1:500, id = No Id -> 203.0.113.1:500, id = No Id ikev2_fb_qm_local_id: Using ipv4_subnet(any:0,[0..7]=172.16.1.0/24) as local QM identity ikev2_fb_qm_remote_id: Using ipv4_subnet(any:0,[0..7]=192.168.1.0/24) as remote QM identity ike_send_notify: Connected, SA = { 9e9c73d8 89be2378 - abbed464 36bd025b}, nego = -1 iked_pm_ike_sa_done: local:192.0.2.1, remote:203.0.113.1 IKEv1 IKE negotiation done for local:192.0.2.1, remote:203.0.113.1 IKEv1 with status: Error ok Added (spi=0x86968a35, protocol=0) entry to the spi table Added (spi=0x630753c, protocol=0) entry to the spi table Added (spi=0x86968a35, protocol=ESP dst=192.0.2.1) entry to the peer hash table Added (spi=0xcad56e88, protocol=ESP dst=203.0.113.1) entry to the peer hash table Successfully added ipsec SA PAIR IPSec negotiation done successfully for SA-CFG IPsec for local:192.0.2.1, remote:203.0.113.1 IKEv1
8. Send traffic over the tunnel from Server1 to Host1 and vice versa:
ping 192.168.1.10 PING 192.168.1.10 (192.168.1.10) 56(84) bytes of data. 64 bytes from 192.168.1.10: icmp_seq=1 ttl=63 time=45.9 ms 64 bytes from 192.168.1.10: icmp_seq=2 ttl=63 time=45.2 ms 64 bytes from 192.168.1.10: icmp_seq=3 ttl=63 time=45.5 ms ping 172.16.1.10 PING 172.16.1.10 (172.16.1.10) 56(84) bytes of data. 64 bytes from 172.16.1.10: icmp_seq=1 ttl=63 time=43.9 ms 64 bytes from 172.16.1.10: icmp_seq=2 ttl=63 time=44.1 ms 64 bytes from 172.16.1.10: icmp_seq=3 ttl=63 time=44.4 ms
