Introduction

Internet Protocol Security (IPsec) is a set of protocols defined by the Internet Engineering Task Force (IETF) to secure packet exchange over unprotected IP/IPv6 networks such as the Internet.

IPsec protocol suite can be divided into the following groups:

• Internet Key Exchange (IKE) protocols. Dynamically generates and distributes cryptographic keys for AH and ESP.
• Authentication Header (AH) RFC 4302
• Encapsulating Security Payload (ESP) RFC 4303

Internet Key Exchange Protocol (IKE)

The Internet Key Exchange (IKE) is a protocol that provides authenticated keying material for the Internet Security Association and Key Management Protocol (ISAKMP) framework. There are other key exchange schemes that work with ISAKMP, but IKE is the most widely used one. Together they provide means for authentication of hosts and automatic management of security associations (SA).

Most of the time IKE daemon is doing nothing. There are two possible situations when it is activated:

There is some traffic caught by a policy rule which needs to become encrypted or authenticated, but the policy doesn't have any SAs. The policy notifies the IKE daemon about that, and the IKE daemon initiates a connection to a remote host. IKE daemon responds to remote connection. In both cases, peers establish a connection and execute 2 phases:

• Phase 1 - The peers agree upon algorithms they will use in the following IKE messages and authenticate. The keying material used to derive keys for all SAs and to protect following ISAKMP exchanges between hosts is generated also. This phase should match the following settings:
  • authentication method
  • DH group
  • encryption algorithm
  • exchange mode
  • hash algorithm
  • NAT-T
  • DPD and lifetime (optional)

• Phase 2 - The peers establish one or more SAs that will be used by IPsec to encrypt data. All SAs established by the IKE daemon will have lifetime values (either limiting time, after which SA will become invalid, or amount of data that can be encrypted by this SA, or both). This phase should match the following settings:
  • IPsec protocol
  • mode (tunnel or transport)
  • authentication method
  • PFS (DH) group
  • lifetime

IKE can optionally provide a Perfect Forward Secrecy (PFS), which is a property of key exchanges, that, in turn, means for IKE that compromising the long term phase 1 key will not allow to easily gain access to all IPsec data that is protected by SAs established through this phase 1. It means an additional keying material is generated for each phase 2.

The generation of keying material is computationally very expensive. Exempli Gratia, the use of the modp8192 group can take several seconds even on a very fast computer. It usually takes place once per phase 1 exchange, which happens only once between any host pair and then is kept for a long time. PFS adds this expensive operation also to each phase 2 exchange.

Diffie-Hellman Groups

Diffie-Hellman (DH) key exchange protocol allows two parties without any initial shared secret to create one securely. The following Modular Exponential (MODP) and Elliptic Curve (EC2N) Diffie-Hellman (also known as "Oakley") Groups are supported:

More on standards can be found here.

IKE Traffic

To avoid problems with IKE packets hit some SPD rule and require to encrypt it with not yet established SA (that this packet perhaps is trying to establish), locally originated packets with UDP source port 500 are not processed with SPD. The same way packets with UDP destination port 500 that are to be delivered locally are not processed in incoming policy checks.

Setup Procedure

To get IPsec to work with automatic keying using IKE-ISAKMP you will have to configure policy, peer, and proposal (optional) entries.

EAP Authentication methods

EAP-TLS on Windows is called "Smart Card or other certificates".

Authentication Header (AH)

AH is a protocol that provides authentication of either all or part of the contents of a datagram through the addition of a header that is calculated based on the values in the datagram. What parts of the datagram are used for the calculation, and the placement of the header depends on whether tunnel or transport mode is used.

The presence of the AH header allows to verify the integrity of the message but doesn't encrypt it. Thus, AH provides authentication but not privacy. Another protocol (ESP) is considered superior, it provides data privacy and also its own authentication method.

RouterOS supports the following authentication algorithms for AH:

• SHA2 (256, 512)
• SHA1
• MD5

Transport mode

In transport mode, the AH header is inserted after the IP header. IP data and header is used to calculate authentication value. IP fields that might change during transit, like TTL and hop count, are set to zero values before authentication.

Tunnel mode

In tunnel mode, the original IP packet is encapsulated within a new IP packet. All of the original IP packets are authenticated.

Encapsulating Security Payload (ESP)

Encapsulating Security Payload (ESP) uses shared key encryption to provide data privacy. ESP also supports its own authentication scheme like that used in AH.

ESP packages its fields in a very different way than AH. Instead of having just a header, it divides its fields into three components:

• ESP Header - Comes before the encrypted data and its placement depends on whether ESP is used in transport mode or tunnel mode.
• ESP Trailer - This section is placed after the encrypted data. It contains padding that is used to align the encrypted data.
• ESP Authentication Data - This field contains an Integrity Check Value (ICV), computed in a manner similar to how the AH protocol works, for when ESP's optional authentication feature is used.

Transport mode

In transport mode, the ESP header is inserted after the original IP header. ESP trailer and authentication value are added to the end of the packet. In this mode only the IP payload is encrypted and authenticated, the IP header is not secured.

Tunnel mode

In tunnel mode, an original IP packet is encapsulated within a new IP packet thus securing IP payload and IP header.

Encryption algorithms

RouterOS ESP supports various encryption and authentication algorithms.

Authentication:

• MD5
• SHA1
• SHA2 (256-bit, 512-bit)

Encryption:

• AES - 128-bit, 192-bit, and 256-bit key AES-CBC, AES-CTR, and AES-GCM algorithms;
• Blowfish - added since v4.5
• Twofish - added since v4.5
• Camellia - 128-bit, 192-bit, and 256-bit key Camellia encryption algorithm added since v4.5
• DES - 56-bit DES-CBC encryption algorithm;
• 3DES - 168-bit DES encryption algorithm;

Hardware acceleration

Hardware acceleration allows doing a faster encryption process by using a built-in encryption engine inside the CPU.

List of devices with hardware acceleration is available here

* supported only 128 bit and 256 bit key sizes

** only manufactured since 2016, serial numbers that begin with number 5 and 7

*** AES-CBC and AES-CTR only encryption is accelerated, hashing done in software

**** DES is not supported, only 3DES and AES-CBC

IPsec throughput results of various encryption and hash algorithm combinations are published on the MikroTik products page.

Policies

The policy table is used to determine whether security settings should be applied to a packet.

Properties

Read-only properties

Statistics

This menu shows various IPsec statistics and errors.

Read-only properties

Proposals

Proposal information that will be sent by IKE daemons to establish SAs for certain policies.

Properties

Read-only properties

Groups

In this menu, it is possible to create additional policy groups used by policy templates.

Properties

Peers

Peer configuration settings are used to establish connections between IKE daemons. This connection then will be used to negotiate keys and algorithms for SAs. Exchange mode is the only unique identifier between the peers, meaning that there can be multiple peer configurations with the same remote-address as long as a different exchange-mode is used.

Properties

Read-only properties

Identities

Identities are configuration parameters that are specific to the remote peer. The main purpose of identity is to handle authentication and verify the peer's integrity.

Properties

Read only properties

Profiles

Profiles define a set of parameters that will be used for IKE negotiation during Phase 1. These parameters may be common with other peer configurations.

Properties

Active Peers

This menu provides various statistics about remote peers that currently have established phase 1 connection.

Read only properties

Commands

Mode configs

ISAKMP and IKEv2 configuration attributes are configured in this menu.

Properties

Read-only properties

Installed SAs

This menu provides information about installed security associations including the keys.

Read-only properties

Commands

Keys

This menu lists all imported public and private keys, that can be used for peer authentication. Menu has several commands to work with keys.

Properties

Read-only properties

Commands

Settings

Application Guides

RoadWarrior client with NAT

Consider setup as illustrated below. RouterOS acts as a RoadWarrior client connected to Office allowing access to its internal resources.

A tunnel is established, a local mode-config IP address is received and a set of dynamic policies are generated.

[admin@mikrotik] > ip ipsec policy print 
Flags: T - template, X - disabled, D - dynamic, I - invalid, A - active, * - default 
0 T * group=default src-address=::/0 dst-address=::/0 protocol=all proposal=default template=yes 

1 DA src-address=192.168.77.254/32 src-port=any dst-address=10.5.8.0/24 dst-port=any protocol=all 
action=encrypt level=unique ipsec-protocols=esp tunnel=yes sa-src-address=10.155.107.8 
sa-dst-address=10.155.107.9 proposal=default ph2-count=1 

2 DA src-address=192.168.77.254/32 src-port=any dst-address=192.168.55.0/24 dst-port=any protocol=all 
action=encrypt level=unique ipsec-protocols=esp tunnel=yes sa-src-address=10.155.107.8 
sa-dst-address=10.155.107.9 proposal=default ph2-count=1 

Currently, only packets with a source address of 192.168.77.254/32 will match the IPsec policies. For a local network to be able to reach remote subnets, it is necessary to change the source address of local hosts to the dynamically assigned mode config IP address. It is possible to generate source NAT rules dynamically. This can be done by creating a new address list that contains all local networks that the NAT rule should be applied. In our case, it is 192.168.88.0/24.

/ip firewall address-list add address=192.168.88.0/24 list=local-RW

By specifying the address list under the mode-config initiator configuration, a set of source NAT rules will be dynamically generated.

/ip ipsec mode-config set [ find name="request-only" ] src-address-list=local-RW

When the IPsec tunnel is established, we can see the dynamically created source NAT rules for each network. Now every host in 192.168.88.0/24 is able to access Office's internal resources.

[admin@mikrotik] > ip firewall nat print 
Flags: X - disabled, I - invalid, D - dynamic 
0 D ;;; ipsec mode-config
chain=srcnat action=src-nat to-addresses=192.168.77.254 dst-address=192.168.55.0/24 src-address-list=local-RW

1 D ;;; ipsec mode-config
chain=srcnat action=src-nat to-addresses=192.168.77.254 dst-address=10.5.8.0/24 src-address-list=local-RW

Allow only IPsec encapsulated traffic

There are some scenarios where for security reasons you would like to drop access from/to specific networks if incoming/outgoing packets are not encrypted. For example, if we have L2TP/IPsec setup we would want to drop nonencrypted L2TP connection attempts.

There are several ways how to achieve this:

• Using IPsec policy matcher in firewall;
• Using generic IPsec policy with action set to drop and lower priority (can be used in Road Warrior setups where dynamic policies are generated);
• By setting DSCP or priority in mangle and matching the same values in firewall after decapsulation.

IPsec policy matcher

Let's set up an IPsec policy matcher to accept all packets that matched any of the IPsec policies and drop the rest:

add chain=input comment="ipsec policy matcher" in-interface=WAN ipsec-policy=in,ipsec
add action=drop chain=input comment="drop all" in-interface=WAN log=yes

IPsec policy matcher takes two parameters direction, policy. We used incoming direction and IPsec policy. IPsec policy option allows us to inspect packets after decapsulation, so for example, if we want to allow only GRE encapsulated packet from a specific source address and drop the rest we could set up the following rules:

add chain=input comment="ipsec policy matcher" in-interface=WAN ipsec-policy=in,ipsec protocol=gre src=address=192.168.33.1
add action=drop chain=input comment="drop all" in-interface=WAN log=yes

For L2TP rule set would be:

add chain=input comment="ipsec policy matcher" in-interface=WAN ipsec-policy=in,ipsec protocol=udp dst-port=1701
add action=drop chain=input protocol=udp dst-port=1701 comment="drop l2tp" in-interface=WAN log=yes

Using generic IPsec policy

The trick of this method is to add a default policy with an action drop. Let's assume we are running an L2TP/IPsec server on a public 1.1.1.1 address and we want to drop all nonencrypted L2TP:

/ip ipsec policy
add src-address=1.1.1.1 dst-address=0.0.0.0/0 sa-src-address=1.1.1.1 protocol=udp src-port=1701 tunnel=yes action=discard

Now router will drop any L2TP unencrypted incoming traffic, but after a successful L2TP/IPsec connection dynamic policy is created with higher priority than it is on default static rule, and packets matching that dynamic rule can be forwarded.

[admin@rack2_10g1] /ip ipsec policy> print
Flags: T - template, X - disabled, D - dynamic, I - inactive, * - default
0 T * group=default src-address=::/0 dst-address=::/0 protocol=all
proposal=default template=yes

1 D src-address=1.1.1.1/32 src-port=1701 dst-address=10.5.130.71/32
dst-port=any protocol=udp action=encrypt level=require
ipsec-protocols=esp tunnel=no sa-src-address=1.1.1.1
sa-dst-address=10.5.130.71

2 src-address=1.1.1.1/32 src-port=1701 dst-address=0.0.0.0/0
dst-port=any protocol=udp action=discard level=unique
ipsec-protocols=esp tunnel=yes sa-src-address=1.1.1.1
sa-dst-address=0.0.0.0 proposal=default manual-sa=none

Manually specifying local-address parameter under Peer configuration

Using different routing table

IPsec, as any other service in RouterOS, uses the main routing table regardless of what local-address parameter is used for Peer configuration. It is necessary to apply routing marks to both IKE and IPSec traffic.

Consider the following example. There are two default routes - one in the main routing table and another in the routing table "backup". It is necessary to use the backup link for the IPsec site to site tunnel.

[admin@pair_r1] > /ip route print detail 
Flags: X - disabled, A - active, D - dynamic, C - connect, S - static, r - rip, b - bgp, o - ospf, m - mme, B - blackhole, U - unreachable, P - prohibit 
0 A S dst-address=0.0.0.0/0 gateway=10.155.107.1 gateway-status=10.155.107.1 reachable via ether1 distance=1 scope=30 target-scope=10 routing-mark=backup 

1 A S dst-address=0.0.0.0/0 gateway=172.22.2.115 gateway-status=172.22.2.115 reachable via ether2 distance=1 scope=30 target-scope=10 

2 ADC dst-address=10.155.107.0/25 pref-src=10.155.107.8 gateway=ether1 gateway-status=ether1 reachable distance=0 scope=10 

3 ADC dst-address=172.22.2.0/24 pref-src=172.22.2.114 gateway=ether2 gateway-status=ether2 reachable distance=0 scope=10 

4 ADC dst-address=192.168.1.0/24 pref-src=192.168.1.1 gateway=bridge-local gateway-status=ether2 reachable distance=0 scope=10 

[admin@pair_r1] > /ip firewall nat print 
Flags: X - disabled, I - invalid, D - dynamic 
0 chain=srcnat action=masquerade out-interface=ether1 log=no log-prefix="" 

1 chain=srcnat action=masquerade out-interface=ether2 log=no log-prefix="" 

IPsec peer and policy configurations are created using the backup link's source address, as well as the NAT bypass rule for IPsec tunnel traffic.

/ip ipsec peer
add address=10.155.130.136/32 local-address=10.155.107.8 secret=test
/ip ipsec policy
add sa-src-address=10.155.107.8 src-address=192.168.1.0/24 dst-address=172.16.0.0/24 sa-dst-address=10.155.130.136 tunnel=yes
/ip firewall nat
add action=accept chain=srcnat src-address=192.168.1.0/24 dst-address=172.16.0.0/24 place-before=0

Currently, we see "phase1 negotiation failed due to time up" errors in the log. It is because IPsec tries to reach the remote peer using the main routing table with an incorrect source address. It is necessary to mark UDP/500, UDP/4500, and ipsec-esp packets using Mangle:

/ip firewall mangle
add action=mark-connection chain=output connection-mark=no-mark dst-address=10.155.130.136 dst-port=500,4500 new-connection-mark=ipsec passthrough=yes protocol=udp
add action=mark-connection chain=output connection-mark=no-mark dst-address=10.155.130.136 new-connection-mark=ipsec passthrough=yes protocol=ipsec-esp
add action=mark-routing chain=output connection-mark=ipsec new-routing-mark=backup passthrough=no

Using the same routing table with multiple IP addresses

Consider the following example. There are multiple IP addresses from the same subnet on the public interface. Masquerade rule is configured on out-interface. It is necessary to use one of the IP addresses explicitly.

[admin@pair_r1] > /ip address print 
Flags: X - disabled, I - invalid, D - dynamic 
# ADDRESS NETWORK INTERFACE
0 192.168.1.1/24 192.168.1.0 bridge-local
1 172.22.2.1/24 172.22.2.0 ether1
2 172.22.2.2/24 172.22.2.0 ether1
3 172.22.2.3/24 172.22.2.0 ether1

[admin@pair_r1] > /ip route print 
Flags: X - disabled, A - active, D - dynamic, C - connect, S - static, r - rip, b - bgp, o - ospf, m - mme, B - blackhole, U - unreachable, P - prohibit 
# DST-ADDRESS PREF-SRC GATEWAY DISTANCE
1 A S 0.0.0.0/0 172.22.2.115 1
3 ADC 172.22.2.0/24 172.22.2.1 ether1 0
4 ADC 192.168.1.0/24 192.168.1.1 bridge-local 0

[admin@pair_r1] /ip firewall nat> print 
Flags: X - disabled, I - invalid, D - dynamic 
0 chain=srcnat action=masquerade out-interface=ether1 log=no log-prefix="" 

IPsec peer and policy configuration is created using one of the public IP addresses.

/ip ipsec peer
add address=10.155.130.136/32 local-address=172.22.2.3 secret=test
/ip ipsec policy
add sa-src-address=172.22.2.3 src-address=192.168.1.0/24 dst-address=172.16.0.0/24 sa-dst-address=10.155.130.136 tunnel=yes
/ip firewall nat
add action=accept chain=srcnat src-address=192.168.1.0/24 dst-address=172.16.0.0/24 place-before=0

Currently, the phase 1 connection uses a different source address than we specified, and "phase1 negotiation failed due to time up" errors are shown in the logs. This is because masquerade is changing the source address of the connection to match the pref-src address of the connected route. The solution is to exclude connections from the public IP address from being masqueraded.

/ip firewall nat
add action=accept chain=srcnat protocol=udp src-port=500,4500 place-before=0

Application examples

Site to Site IPsec (IKEv1) tunnel

Consider setup as illustrated below. Two remote office routers are connected to the internet and office workstations are behind NAT. Each office has its own local subnet, 10.1.202.0/24 for Office1 and 10.1.101.0/24 for Office2. Both remote offices need secure tunnels to local networks behind routers.

Site 1 configuration

Start off by creating a new Phase 1profileand Phase 2proposalentries using stronger or weaker encryption parameters that suit your needs. It is advised to create separate entries for each menu so that they are unique for each peer in case it is necessary to adjust any of the settings in the future. These parameters must match between the sites or else the connection will not establish.

/ip ipsec profile
add dh-group=modp2048 enc-algorithm=aes-128 name=ike1-site2
/ip ipsec proposal
add enc-algorithms=aes-128-cbc name=ike1-site2 pfs-group=modp2048

Continue by configuring a peer. Specify the address of the remote router. This address should be reachable through UDP/500 and UDP/4500 ports, so make sure appropriate actions are taken regarding the router's firewall. Specify the name for this peer as well as the newly created profile.

/ip ipsec peer
add address=192.168.80.1/32 name=ike1-site2 profile=ike1-site2

The next step is to create an identity. For a basic pre-shared key secured tunnel, there is nothing much to set except for a strong secret and the peer to which this identity applies.

/ip ipsec identity
add peer=ike1-site2 secret=thisisnotasecurepsk

Lastly, create a policy that controls the networks/hosts between whom traffic should be encrypted.

/ip ipsec policy
add src-address=10.1.202.0/24 src-port=any dst-address=10.1.101.0/24 dst-port=any tunnel=yes action=encrypt proposal=ike1-site2 peer=ike1-site2

Site 2 configuration

Office 2 configuration is almost identical to Office 1 with proper IP address configuration. Start off by creating a new Phase 1 profile and Phase 2 proposal entries:

/ip ipsec profile
add dh-group=modp2048 enc-algorithm=aes-128 name=ike1-site1
/ip ipsec proposal
add enc-algorithms=aes-128-cbc name=ike1-site1 pfs-group=modp2048

Next is the peer and identity:

/ip ipsec peer
add address=192.168.90.1/32 name=ike1-site1 profile=ike1-site1
/ip ipsec identity
add peer=ike1-site1 secret=thisisnotasecurepsk

When it is done, create a policy:

/ip ipsec policy
add src-address=10.1.101.0/24 src-port=any dst-address=10.1.202.0/24 dst-port=any tunnel=yes action=encrypt proposal=ike1-site1 peer=ike1-site1

At this point, the tunnel should be established and two IPsec Security Associations should be created on both routers:

/ip ipsec
active-peers print
installed-sa print

NAT and Fasttrack Bypass

At this point if you try to send traffic over the IPsec tunnel, it will not work, packets will be lost. This is because both routers have NAT rules (masquerade) that are changing source addresses before a packet is encrypted. A router is unable to encrypt the packet because the source address does not match the address specified in the policy configuration. For more information see the IPsec packet flow example.

To fix this we need to set up IP/Firewall/NAT bypass rule.

Office 1 router:

/ip firewall nat
add chain=srcnat action=accept place-before=0 src-address=10.1.202.0/24 dst-address=10.1.101.0/24

Office 2 router:

/ip firewall nat
add chain=srcnat action=accept place-before=0 src-address=10.1.101.0/24 dst-address=10.1.202.0/24

It is very important that the bypass rule is placed at the top of all other NAT rules.

Another issue is if you have IP/Fasttrack enabled, the packet bypasses IPsec policies. So we need to add accept rule before FastTrack.

/ip firewall filter
add chain=forward action=accept place-before=1
src-address=10.1.101.0/24 dst-address=10.1.202.0/24 connection-state=established,related
add chain=forward action=accept place-before=1
src-address=10.1.202.0/24 dst-address=10.1.101.0/24 connection-state=established,related

However, this can add a significant load to the router's CPU if there is a fair amount of tunnels and significant traffic on each tunnel.

The solution is to use IP/Firewall/Raw to bypass connection tracking, that way eliminating the need for filter rules listed above and reducing the load on CPU by approximately 30%.

/ip firewall raw
add action=notrack chain=prerouting src-address=10.1.101.0/24 dst-address=10.1.202.0/24
add action=notrack chain=prerouting src-address=10.1.202.0/24 dst-address=10.1.101.0/24

Site to Site GRE tunnel over IPsec (IKEv2) using DNS

This example explains how it is possible to establish a secure and encrypted GRE tunnel between two RouterOS devices when one or both sites do not have a static IP address. Before making this configuration possible, it is necessary to have a DNS name assigned to one of the devices which will act as a responder (server). For simplicity, we will use RouterOS built-in DDNS service IP/Cloud.

Site 1 (server) configuration

This is the side that will listen to incoming connections and act as a responder. We will use mode config to provide an IP address for the second site, but first, create a loopback (blank) bridge and assign an IP address to it that will be used later for GRE tunnel establishment.

/interface bridge 
add name=loopback
/ip address
add address=192.168.99.1 interface=loopback

Continuing with the IPsec configuration, start off by creating a new Phase 1 profile and Phase 2 proposal entries using stronger or weaker encryption parameters that suit your needs. Note that this configuration example will listen to all incoming IKEv2 requests, meaning the profile configuration will be shared between all other configurations (e.g. RoadWarrior).

/ip ipsec profile
add dh-group=ecp256,modp2048,modp1024 enc-algorithm=aes-256,aes-192,aes-128 name=ike2
/ip ipsec proposal
add auth-algorithms=null enc-algorithms=aes-128-gcm name=ike2-gre pfs-group=none

Next, create a new mode config entry with responder=yes. This will provide an IP configuration for the other site as well as the host (loopback address) for policy generation.

/ip ipsec mode-config
add address=192.168.99.2 address-prefix-length=32 name=ike2-gre split-include=192.168.99.1/32 system-dns=no

It is advised to create a new policy group to separate this configuration from any existing or future IPsec configuration.

/ip ipsec policy group
add name=ike2-gre

Now it is time to set up a new policy template that will match the remote peers new dynamic address and the loopback address.

/ip ipsec policy
add dst-address=192.168.99.2/32 group=ike2-gre proposal=ike2-gre src-address=192.168.99.1/32 template=yes

The next step is to create a peer configuration that will listen to all IKEv2 requests. If you already have such an entry, you can skip this step.

/ip ipsec peer
add exchange-mode=ike2 name=ike2 passive=yes profile=ike2

Lastly, set up an identity that will match our remote peer by pre-shared-key authentication with a specific secret.

/ip ipsec identity
add generate-policy=port-strict mode-config=ike2-gre peer=ike2 policy-template-group=ike2-gre secret=test

The server side is now configured and listening to all IKEv2 requests. Please make sure the firewall is not blocking UDP/4500 port.

The last step is to create the GRE interface itself. This can also be done later when an IPsec connection is established from the client-side.

/interface gre
add local-address=192.168.99.1 name=gre-tunnel1 remote-address=192.168.99.2

Configure IP address and route to remote network through GRE interface.

/ip address
add address=172.16.1.1/30 interface=gre-tunnel1
/ip route
add dst-network=10.1.202.0/24 gateway=172.16.1.2

Site 2 (client) configuration

Similarly to server configuration, start off by creating a new Phase 1 profile and Phase 2 proposal configurations. Since this site will be the initiator, we can use a more specific profile configuration to control which exact encryption parameters are used, just make sure they overlap with what is configured on the server-side.

/ip ipsec profile
add dh-group=ecp256 enc-algorithm=aes-256 name=ike2-gre
/ip ipsec proposal
add auth-algorithms=null enc-algorithms=aes-128-gcm name=ike2-gre pfs-group=none

Next, create a new mode config entry with responder=no. This will make sure the peer requests IP and split-network configuration from the server.

/ip ipsec mode-config
add name=ike2-gre responder=no

It is also advised to create a new policy group to separate this configuration from any existing or future IPsec configuration.

/ip ipsec policy group
add name=ike2-gre

Create a new policy template on the client-side as well.

/ip ipsec policy
add dst-address=192.168.99.1/32 group=ike2-gre proposal=ike2-gre src-address=192.168.99.2/32 template=yes

Move on to peer configuration. Now we can specify the DNS name for the server under the address parameter. Obviously, you can use an IP address as well.

/ip ipsec peer
add address=n.mynetname.net exchange-mode=ike2 name=p1.ez profile=ike2-gre

Lastly, create an identity for our newly created peers.

/ip ipsec identity
add generate-policy=port-strict mode-config=ike2-gre peer=p1.ez policy-template-group=ike2-gre secret=test

If everything was done properly, there should be a new dynamic policy present.

/ip ipsec policy print 
Flags: T - template, X - disabled, D - dynamic, I - invalid, A - active, * - default 
0 T * group=default src-address=::/0 dst-address=::/0 protocol=all proposal=default template=yes

1 T group=ike2-gre src-address=192.168.99.2/32 dst-address=192.168.99.1/32 protocol=all proposal=ike2-gre template=yes

2 DA src-address=192.168.99.2/32 src-port=any dst-address=192.168.99.1/32 dst-port=any protocol=all action=encrypt level=unique ipsec-protocols=esp 
tunnel=yes sa-src-address=172.17.2.1 sa-dst-address=172.17.2.2 proposal=ike2-gre ph2-count=1 

A secure tunnel is now established between both sites which will encrypt all traffic between 192.168.99.2 <=> 192.168.99.1 addresses. We can use these addresses to create a GRE tunnel.

/interface gre
add local-address=192.168.99.2 name=gre-tunnel1 remote-address=192.168.99.1

Configure IP address and route to remote network through GRE interface.

/ip address
add address=172.16.1.2/30 interface=gre-tunnel1
/ip route
add dst-network=10.1.101.0/24 gateway=172.16.1.1

Road Warrior setup using IKEv2 with RSA authentication

This example explains how to establish a secure IPsec connection between a device connected to the Internet (road warrior client) and a device running RouterOS acting as a server.

RouterOS server configuration

Before configuring IPsec, it is required to set up certificates. It is possible to use a separate Certificate Authority for certificate management, however in this example, self-signed certificates are generated in RouterOS System/Certificates menu. Some certificate requirements should be met to connect various devices to the server:

• Common name should contain IP or DNS name of the server;
• SAN (subject alternative name) should have IP or DNS of the server;
• EKU (extended key usage) tls-server and tls-client are required.

Considering all requirements above, generate CA and server certificates:

/certificate
add common-name=ca name=ca
sign ca ca-crl-host=2.2.2.2
add common-name=2.2.2.2 subject-alt-name=IP:2.2.2.2 key-usage=tls-server name=server1
sign server1 ca=ca

Now that valid certificates are created on the router, add a new Phase 1 profile and Phase 2 proposal entries with pfs-group=none:

/ip ipsec profile
add name=ike2
/ip ipsec proposal
add name=ike2 pfs-group=none

Mode config is used for address distribution from IP/Pools:

/ip pool
add name=ike2-pool ranges=192.168.77.2-192.168.77.254
/ip ipsec mode-config
add address-pool=ike2-pool address-prefix-length=32 name=ike2-conf

Since that the policy template must be adjusted to allow only specific network policies, it is advised to create a separate policy group and template.

/ip ipsec policy group
add name=ike2-policies
/ip ipsec policy
add dst-address=192.168.77.0/24 group=ike2-policies proposal=ike2 src-address=0.0.0.0/0 template=yes

Create a new IPsec peer entry that will listen to all incoming IKEv2 requests.

/ip ipsec peer
add exchange-mode=ike2 name=ike2 passive=yes profile=ike2

Identity configuration

The identity menu allows to match specific remote peers and assign different configurations for each one of them. First, create a default identity, that will accept all peers, but will verify the peer's identity with its certificate.

/ip ipsec identity
add auth-method=digital-signature certificate=server1 generate-policy=port-strict mode-config=ike2-conf peer=ike2 policy-template-group=ike2-policies

For example, we want to assign a different mode config for user "A", who uses certificate "rw-client1" to authenticate itself to the server. First of all, make sure a new mode config is created and ready to be applied for the specific user.

/ip ipsec mode-config
add address=192.168.66.2 address-prefix-length=32 name=usr_A split-include=192.168.55.0/24 system-dns=no

It is possible to apply this configuration for user "A" by using the match-by=certificate parameter and specifying his certificate with remote-certificate.

/ip ipsec identity
add auth-method=digital-signature certificate=server1 generate-policy=port-strict match-by=certificate mode-config=usr_A peer=ike2 policy-template-group=ike2-policies remote-certificate=rw-client1

(Optional) Split tunnel configuration

Split tunneling is a method that allows road warrior clients to only access a specific secured network and at the same time send the rest of the traffic based on their internal routing table (as opposed to sending all traffic over the tunnel). To configure split tunneling, changes to mode config parameters are needed.

For example, we will allow our road warrior clients to only access the 10.5.8.0/24 network.

/ip ipsec mode-conf
set [find name="rw-conf"] split-include=10.5.8.0/24

It is also possible to send a specific DNS server for the client to use. By default, system-dns=yes is used, which sends DNS servers that are configured on the router itself in IP/DNS. We can force the client to use a different DNS server by using the static-dns parameter.

/ip ipsec mode-conf
set [find name="rw-conf"] system-dns=no static-dns=10.5.8.1

While it is possible to adjust the IPsec policy template to only allow road warrior clients to generate policies to network configured by split-include parameter, this can cause compatibility issues with different vendor implementations (see known limitations). Instead of adjusting the policy template, allow access to a secured network in IP/Firewall/Filter and drop everything else.

/ip firewall filter
add action=drop chain=forward src-address=192.168.77.0/24 dst-address=!10.5.8.0/24

Generating client certificates

To generate a new certificate for the client and sign it with a previously created CA.

/certificate
add common-name=rw-client1 name=rw-client1 key-usage=tls-client
sign rw-client1 ca=ca

PKCS12 format is accepted by most client implementations, so when exporting the certificate, make sure PKCS12 is specified.

/certificate
export-certificate rw-client1 export-passphrase=1234567890 type=pkcs12

A file named cert_export_rw-client1.p12 is now located in the routers System/File section. This file should be securely transported to the client's device.

Typically PKCS12 bundle contains also a CA certificate, but some vendors may not install this CA, so a self-signed CA certificate must be exported separately using PEM format.

/certificate
export-certificate ca type=pem

A file named cert_export_ca.crt is now located in the routers System/File section. This file should also be securely transported to the client's device.

PEM is another certificate format for use in client software that does not support PKCS12. The principle is pretty much the same.

/certificate
export-certificate ca
export-certificate rw-client1 export-passphrase=1234567890

Three files are now located in the routers Files section: cert_export_ca.crt, cert_export_rw-client1.crt and cert_export_rw-client1.key which should be securely transported to the client device.

Known limitations

Here is a list of known limitations by popular client software IKEv2 implementations.

• Windows will always ignore networks received by split-include and request policy with destination 0.0.0.0/0 (TSr). When IPsec-SA is generated, Windows requests DHCP option 249 to which RouterOS will respond with configured split-include networks automatically.

• Both Apple macOS and iOS will only accept the first split-include network.

• Both Apple macOS and iOS will use the DNS servers from system-dns and static-dns parameters only when 0.0.0.0/0 split-include is used.

• While some implementations can make use of different PFS group for phase 2, it is advised to use pfs-group=none under proposals to avoid any compatibility issues.

RouterOS client configuration

Import a PKCS12 format certificate in RouterOS.

/certificate import file-name=cert_export_RouterOS_client.p12 passphrase=1234567890

There should now be the self-signed CA certificate and the client certificate in the Certificate menu. Find out the name of the client certificate.

/certificate print

cert_export_RouterOS_client.p12_0 is the client certificate.

It is advised to create a separate Phase 1 profile and Phase 2 proposal configurations to not interfere with any existing IPsec configuration.

/ip ipsec profile
add name=ike2-rw
/ip ipsec proposal
add name=ike2-rw pfs-group=none

While it is possible to use the default policy template for policy generation, it is better to create a new policy group and template to separate this configuration from any other IPsec configuration.

/ip ipsec policy group
add name=ike2-rw
/ip ipsec policy
add group=ike2-rw proposal=ike2-rw template=yes

Create a new mode config entry with responder=no that will request configuration parameters from the server.

/ip ipsec mode-config
add name=ike2-rw responder=no

Lastly, create peer and identity configurations.

/ip ipsec peer
add address=2.2.2.2/32 exchange-mode=ike2 name=ike2-rw-client
/ip ipsec identity
add auth-method=digital-signature certificate=cert_export_RouterOS_client.p12_0 generate-policy=port-strict mode-config=ike2-rw peer=ike2-rw-client policy-template-group=ike2-rw

Verify that the connection is successfully established.

/ip ipsec
active-peers print
installed-sa print

Enabling dynamic source NAT rule generation

If we look at the generated dynamic policies, we see that only traffic with a specific (received by mode config) source address will be sent through the tunnel. But a router in most cases will need to route a specific device or network through the tunnel. In such case, we can use source NAT to change the source address of packets to match the mode config address. Since the mode config address is dynamic, it is impossible to create a static source NAT rule. In RouterOS, it is possible to generate dynamic source NAT rules for mode config clients.

For example, we have a local network 192.168.88.0/24 behind the router and we want all traffic from this network to be sent over the tunnel. First of all, we have to make a new IP/Firewall/Address list which consists of our local network

/ip firewall address-list
add address=192.168.88.0/24 list=local

When it is done, we can assign the newly created IP/Firewall/Address list to the mode config configuration.

/ip ipsec mode-config
set [ find name=ike2-rw ] src-address-list=local

Verify correct source NAT rule is dynamically generated when the tunnel is established.

[admin@MikroTik] > /ip firewall nat print 
Flags: X - disabled, I - invalid, D - dynamic 
0 D ;;; ipsec mode-config
chain=srcnat action=src-nat to-addresses=192.168.77.254 src-address-list=local dst-address-list=!local

Windows client configuration

Open PKCS12 format certificate file on the Windows computer. Install the certificate by following the instructions. Make sure you select the Local Machine store location. You can now proceed to Network and Internet settings -> VPN and add a new configuration. Fill in the Connection name, Server name, or address parameters. Select IKEv2 under VPN type. When it is done, it is necessary to select "Use machine certificates". This can be done in Network and Sharing Center by clicking the Properties menu for the VPN connection. The setting is located under the Security tab.

Currently, Windows 10 is compatible with the following Phase 1 ( profiles) and Phase 2 ( proposals) proposal sets:

macOS client configuration

Open the PKCS12 format certificate file on the macOS computer and install the certificate in the "System" keychain. It is necessary to mark the CA certificate as trusted manually since it is self-signed. Locate the certificate macOS Keychain Access app under the System tab and mark it as Always Trust.

You can now proceed to System Preferences -> Network and add a new configuration by clicking the + button. Select Interface: VPN, VPN Type: IKEv2 and name your connection. Remote ID must be set equal to common-name or subjAltName of server's certificate. Local ID can be left blank. Under Authentication Settings select None and choose the client certificate. You can now test the connectivity.

Currently, macOS is compatible with the following Phase 1 ( profiles) and Phase 2 ( proposals) proposal sets:

iOS client configuration

Typically PKCS12 bundle contains also a CA certificate, but iOS does not install this CA, so a self-signed CA certificate must be installed separately using PEM format. Open these files on the iOS device and install both certificates by following the instructions. It is necessary to mark the self-signed CA certificate as trusted on the iOS device. This can be done in Settings -> General -> About -> Certificate Trust Settings menu. When it is done, check whether both certificates are marked as "verified" under the Settings -> General -> Profiles menu.

You can now proceed to Settings -> General -> VPN menu and add a new configuration. Remote ID must be set equal to common-name or subjAltName of server's certificate. Local ID can be left blank.

Currently, iOS is compatible with the following Phase 1 ( profiles) and Phase 2 ( proposals) proposal sets:

Android (strongSwan) client configuration

Currently, there is no IKEv2 native support in Android, however, it is possible to use strongSwan from Google Play Store which brings IKEv2 to Android. StrongSwan accepts PKCS12 format certificates, so before setting up the VPN connection in strongSwan, make sure you download the PKCS12 bundle to your Android device. When it is done, create a new VPN profile in strongSwan, type in the server IP, and choose "IKEv2 Certificate" as VPN Type. When selecting a User certificate, press Install and follow the certificate extract procedure by specifying the PKCS12 bundle. Save the profile and test the connection by pressing on the VPN profile.

It is possible to specify custom encryption settings in strongSwan by ticking the "Show advanced settings" checkbox. Currently, strongSwan by default is compatible with the following Phase 1 ( profiles) and Phase 2 ( proposals) proposal sets:

Linux (strongSwan) client configuration

Download the PKCS12 certificate bundle and move it to /etc/ipsec.d/private directory.

Add exported passphrase for the private key to /etc/ipsec.secrets file where "strongSwan_client.p12" is the file name and "1234567890" is the passphrase.

: P12 strongSwan_client.p12 "1234567890"

Add a new connection to /etc/ipsec.conf file

conn "ikev2"
keyexchange=ikev2
ike=aes128-sha1-modp2048
esp=aes128-sha1
leftsourceip=%modeconfig
leftcert=strongSwan_client.p12
leftfirewall=yes
right=2.2.2.2
rightid="CN=2.2.2.2"
rightsubnet=0.0.0.0/0
auto=add

You can now restart (or start) the ipsec daemon and initialize the connection

$ ipsec restart
$ ipsec up ikev2

Road Warrior setup using IKEv2 with EAP-MSCHAPv2 authentication handled by User Manager (RouterOS v7)

This example explains how to establish a secure IPsec connection between a device connected to the Internet (road warrior client) and a device running RouterOS acting as an IKEv2 server and User Manager. It is possible to run User Manager on a separate device in network, however in this example both User Manager and IKEv2 server will be configured on the same device (Office).

RouterOS server configuration

Requirements

For this setup to work there are several prerequisites for the router:

1. Router's IP address should have a valid public DNS record - IP Cloud could be used to achieve this.
2. Router should be reachable through port TCP/80 over the Internet - if the server is behind NAT, port forwarding should be configured.
3. User Manager package should be installed on the router.

Generating Let's Encrypt certificate

During the EAP-MSCHAPv2 authentication, TLS handshake has to take place, which means the server has to have a certificate that can be validated by the client. To simplify this step, we will use Let's Encrypt certificate which can be validated by most operating systems without any intervention by the user. To generate the certificate, simply enable SSL certificate under the Certificates menu. By default the command uses the dynamic DNS record provided by IP Cloud, however a custom DNS name can also be specified. Note that, the DNS record should point to the router.

/certificate enable-ssl-certificate

If the certificate generation succeeded, you should see the Let's Encrypt certificate installed under the Certificates menu.

/certificate print detail where name~"letsencrypt"

Configuring User Manager

First of all, allow receiving RADIUS requests from the localhost (the router itself):

/user-manager router
add address=127.0.0.1 comment=localhost name=local shared-secret=test

Enable the User Manager and specify the Let's Encrypt certificate (replace the name of the certificate to the one installed on your device) that will be used to authenticate the users.

/user-manager
set certificate="letsencrypt_2021-04-09T07:10:55Z" enabled=yes

Lastly add users and their credentials that clients will use to authenticate to the server.

/user-manager user
add name=user1 password=password

Configuring RADIUS client

For the router to use RADIUS server for user authentication, it is required to add a new RADIUS client that has the same shared secret that we already configured on User Manager.

/radius
add address=127.0.0.1 secret=test service=ipsec

IPsec (IKEv2) server configuration

Add a new Phase 1 profile and Phase 2 proposal entries with pfs-group=none:

/ip ipsec profile
add name=ike2
/ip ipsec proposal
add name=ike2 pfs-group=none

Mode config is used for address distribution from IP/Pools.

/ip pool
add name=ike2-pool ranges=192.168.77.2-192.168.77.254
/ip ipsec mode-config
add address-pool=ike2-pool address-prefix-length=32 name=ike2-conf

Since that the policy template must be adjusted to allow only specific network policies, it is advised to create a separate policy group and template.

/ip ipsec policy group
add name=ike2-policies
/ip ipsec policy
add dst-address=192.168.77.0/24 group=ike2-policies proposal=ike2 src-address=0.0.0.0/0 template=yes

Create a new IPsec peer entry which will listen to all incoming IKEv2 requests.

/ip ipsec peer
add exchange-mode=ike2 name=ike2 passive=yes profile=ike2

Lastly create a new IPsec identity entry that will match all clients trying to authenticate with EAP. Note that generated Let's Encrypt certificate must be specified.

/ip ipsec identity
add auth-method=eap-radius certificate="letsencrypt_2021-04-09T07:10:55Z" generate-policy=port-strict mode-config=ike2-conf peer=ike2 \
policy-template-group=ike2-policies

(Optional) Split tunnel configuration

Split tunneling is a method that allows road warrior clients to only access a specific secured network and at the same time send the rest of the traffic based on their internal routing table (as opposed to sending all traffic over the tunnel). To configure split tunneling, changes to mode config parameters are needed.

For example, we will allow our road warrior clients to only access the 10.5.8.0/24 network.

/ip ipsec mode-conf
set [find name="rw-conf"] split-include=10.5.8.0/24

It is also possible to send a specific DNS server for the client to use. By default, system-dns=yes is used, which sends DNS servers that are configured on the router itself in IP/DNS. We can force the client to use a different DNS server by using the static-dns parameter.

/ip ipsec mode-conf
set [find name="rw-conf"] system-dns=no static-dns=10.5.8.1

(Optional) Assigning static IP address to user

Static IP address to any user can be assigned by use of RADIUS Framed-IP-Address attribute.

/user-manager user
set [find name="user1"] attributes=Framed-IP-Address:192.168.77.100 shared-users=1

(Optional) Accounting configuration

To keep track of every user's uptime, download and upload statistics, RADIUS accounting can be used. By default RADIUS accounting is already enabled for IPsec, but it is advised to configure Interim Update timer that sends statistic to the RADIUS server regularly. If the router will handle a lot of simultaneous sessions, it is advised to increase the update timer to avoid increased CPU usage.

/ip ipsec settings
set interim-update=1m

Basic L2TP/IPsec setup

This example demonstrates how to easily set up an L2TP/IPsec server on RouterOS for road warrior connections (works with Windows, Android, iOS, macOS, and other vendor L2TP/IPsec implementations).

RouterOS server configuration

The first step is to enable the L2TP server:

/interface l2tp-server server
set enabled=yes use-ipsec=required ipsec-secret=mySecret default-profile=default

use-ipsec is set to required to make sure that only IPsec encapsulated L2TP connections are accepted.

Now what it does is enables an L2TP server and creates a dynamic IPsec peer with a specified secret.

[admin@MikroTik] /ip ipsec peer> print 
0 D address=0.0.0.0/0 local-address=0.0.0.0 passive=yes port=500 
auth-method=pre-shared-key secret="123" generate-policy=port-strict 
exchange-mode=main-l2tp send-initial-contact=yes nat-traversal=yes 
hash-algorithm=sha1 enc-algorithm=3des,aes-128,aes-192,aes-256 
dh-group=modp1024 lifetime=1d dpd-interval=2m dpd-maximum-failures=5 

The next step is to create a VPN pool and add some users.

/ip pool add name=vpn-pool range=192.168.99.2-192.168.99.100

/ppp profile
set default local-address=192.168.99.1 remote-address=vpn-pool

/ppp secret
add name=user1 password=123
add name=user2 password=234

Now the router is ready to accept L2TP/IPsec client connections.

RouterOS client configuration

For RouterOS to work as L2TP/IPsec client, it is as simple as adding a new L2TP client.

/interface l2tp-client
add connect-to=1.1.1.1 disabled=no ipsec-secret=mySecret name=l2tp-out1 \
password=123 use-ipsec=yes user=user1

It will automatically create dynamic IPsec peer and policy configurations.

IKEv2 EAP between NordVPN and RouterOS

Example available here

Troubleshooting/FAQ

Phase 1 Failed to get a valid proposal

[admin@MikroTik] /log> print
(..)
17:12:32 ipsec,error no suitable proposal found. 
17:12:32 ipsec,error 10.5.107.112 failed to get valid proposal. 
17:12:32 ipsec,error 10.5.107.112 failed to pre-process ph1 packet (side: 1, status 1). 
17:12:32 ipsec,error 10.5.107.112 phase1 negotiation failed. 
(..)

Peers are unable to negotiate encryption parameters causing the connection to drop. To solve this issue, enable IPSec to debug logs and find out which parameters are proposed by the remote peer, and adjust the configuration accordingly.

[admin@MikroTik] /system logging> add topics=ipsec,!debug

[admin@MikroTik] /log> print
(..)
17:21:08 ipsec rejected hashtype: DB(prop#1:trns#1):Peer(prop#1:trns#1) = MD5:SHA 
17:21:08 ipsec rejected enctype: DB(prop#1:trns#2):Peer(prop#1:trns#1) = 3DES-CBC:AES-CBC 
17:21:08 ipsec rejected hashtype: DB(prop#1:trns#2):Peer(prop#1:trns#1) = MD5:SHA 
17:21:08 ipsec rejected enctype: DB(prop#1:trns#1):Peer(prop#1:trns#2) = AES-CBC:3DES-CBC 
17:21:08 ipsec rejected hashtype: DB(prop#1:trns#1):Peer(prop#1:trns#2) = MD5:SHA 
17:21:08 ipsec rejected hashtype: DB(prop#1:trns#2):Peer(prop#1:trns#2) = MD5:SHA 
17:21:08 ipsec,error no suitable proposal found. 
17:21:08 ipsec,error 10.5.107.112 failed to get valid proposal. 
17:21:08 ipsec,error 10.5.107.112 failed to pre-process ph1 packet (side: 1, status 1). 
17:21:08 ipsec,error 10.5.107.112 phase1 negotiation failed. 
(..)

In this example, the remote end requires SHA1 to be used as a hash algorithm, but MD5 is configured on the local router. Setting before the column symbol (:) is configured on the local side, parameter after the column symbol (:) is configured on the remote side.

"phase1 negotiation failed due to time up" what does it mean?

There are communication problems between the peers. Possible causes include - misconfigured Phase 1 IP addresses; firewall blocking UDP ports 500 and 4500; NAT between peers not properly translating IPsec negotiation packets. This error message can also appear when a local-address parameter is not used properly. More information available here.

Random packet drops or connections over the tunnel are very slow, enabling packet sniffer/torch fixes the problem?

Problem is that before encapsulation packets are sent to Fasttrack/FastPath, thus bypassing IPsec policy checking. The solution is to exclude traffic that needs to be encapsulated/decapsulated from Fasttrack, see configuration example here.

How to enable ike2?

For basic configuration enabling ike2 is very simple, just change exchange-mode in peer settings to ike2.

fatal NO-PROPOSAL-CHOSEN notify message?

Remote peer sent notify that it cannot accept proposed algorithms, to find the exact cause of the problem, look at remote peers debug logs or configuration and verify that both client and server have the same set of algorithms.

I can ping only in one direction?

A typical problem in such cases is strict firewall, firewall rules allow the creation of new connections only in one direction. The solution is to recheck firewall rules, or explicitly accept all traffic that should be encapsulated/decapsulated.

Can I allow only encrypted traffic?

Yes, you can, see "Allow only IPsec encapsulated traffic" examples.

I enable IKEv2 REAUTH on StrongSwan and got the error 'initiator did not reauthenticate as requested'

RouterOS does not support rfc4478, reauth must be disabled on StrongSwan.