NAME

DESCRIPTION

In its most basic form, a flow is established between hosts and/or networks, and then Security Associations (SA) are established, which detail how the desired protection will be achieved. IPsec uses flows to determine whether to apply security services to an IP packet or not. iked(8) is used to set up flows and establish SAs automatically, by specifying `ikev2' policies in iked.conf (see AUTOMATIC KEYING POLICIES , below).

Alternative methods of setting up flows and SAs are also possible using manual keying or automatic keying using the older ISAKMP/Oakley a.k.a. IKEv1 protocol. Manual keying is not recommended, but can be convenient for quick setups and testing.

IKED.CONF FILE FORMAT

Macros

User-defined variables may be defined and used later, simplifying the configuration file.

Global Configuration

Global settings for iked(8).

Automatic Keying Policies

Policies to set up IPsec flows and SAs automatically.

Lines beginning with `#' and empty lines are regarded as comments, and ignored. Lines may be split using the `\' character.

Argument names not beginning with a letter, digit, or underscore must be quoted.

Addresses can be specified in CIDR notation (matching netblocks), as symbolic host names, interface names, or interface group names.

Additional configuration files can be included with the include keyword, for example:

include "/etc/macros.conf"

MACROS

For example:

remote_gw = "192.168.3.12"
ikev2 esp from 192.168.7.0/24 to 192.168.8.0/24 peer $remote_gw

GLOBAL CONFIGURATION

set active

Set iked(8) to active mode. This is the default.

set passive

Set iked(8) to passive mode. In passive mode no packets are sent to peers and no connections are initiated by iked(8). This option is used for setups using sasyncd(8) and carp(4) to provide redundancy. iked will run in passive mode until sasyncd has determined that the host is the master and can switch to active mode.

set couple

Load the negotiated security associations (SAs) and flows into the kernel. This is the default.

set decouple

Don't load the negotiated SAs and flows from the kernel. This mode is only useful for testing and debugging.

set ocsp URL

Enable OCSP and set the URL of the OCSP responder. Please note that the matching responder and issuer certificates have to be placed in /usr/local/etc/iked/ocsp/responder.crt and /usr/local/etc/iked/ocsp/issuer.crt.

user name password

iked(8) supports user-based authentication by tunneling the Extensible Authentication Protocol (EAP) over IKEv2. In its most basic form, the users will be authenticated against a local, integrated password database that is configured with the user lines in iked.conf and the name and password arguments. Note that the password has to be specified in plain text which is required to support different challenge-based EAP methods like EAP-MD5 or EAP-MSCHAPv2.

AUTOMATIC KEYING POLICIES

# Set up a VPN:
# First between the gateway machines 192.168.3.1 and 192.168.3.2
# Second between the networks 10.1.1.0/24 and 10.1.2.0/24
ikev2 esp from 192.168.3.1 to 192.168.3.2
ikev2 esp from 10.1.1.0/24 to 10.1.2.0/24 peer 192.168.3.2

For incoming connections from remote peers, the policies are evaluated in sequential order, from first to last. The last matching policy decides what action is taken; if no policy matches the connection, the default action is to ignore the connection attempt or to use the default policy, if set. Please also see the EXAMPLES section for a detailed example of the policy evaluation.

The first time an IKEv2 connection matches a policy, an IKE SA is created; for subsequent packets the connection is identified by the IKEv2 parameters that are stored in the SA without evaluating any policies. After the connection is closed or times out, the IKE SA is automatically removed.

The commands are as follows:

ikev2 [name]

The mandatory ikev2 keyword will identify an IKEv2 automatic keying policy. name is an optional arbitrary string identifying the policy. The name should only occur once in iked.conf or any included files. If omitted, a name will be generated automatically for the policy.

[eval]

The eval option modifies the policy evaluation for this policy. It can be one of quick, skip or default. If a new incoming connection matches a policy with the quick option set, that policy is considered the last matching policy, and evaluation of subsequent policies is skipped. The skip option will disable evaluation of this policy for incoming connections. The default option sets the default policy and should only be specified once.

[mode]

mode specifies the IKEv2 mode to use: one of passive, active or lazy. When passive is specified, iked(8) will not immediately start negotiation of this tunnel, but wait for an incoming request from the remote peer. When active is specified, negotiation will be started at once. When lazy is specified, negotiation will start if and when needed. A negotiation is needed when a packet matches the flow and there is no association for it yet. If omitted, passive mode will be used.

ipcomp

Enable optional support for ipcomp(4), the IP Payload Compression protocol.

[encap]

encap specifies the encapsulation protocol to be used. Possible protocols are esp and ah ; the default is esp.

[af]

This policy only applies to endpoints of the specified address family which can be either inet or inet6. Note that this only matters for IKEv2 endpoints and does not restrict the traffic selectors to negotiate flows with different address families, e.g. IPv6 flows negotiated by IPv4 endpoints.

proto protocol

The optional proto parameter restricts the flow to a specific IP protocol. Common protocols are icmp(4), tcp(4), and udp(4). For a list of all the protocol name to number mappings used by iked(8), see the file /etc/protocols.

from src [port sport] [( srcnat)] to dst [port dport]

Specify one or more traffic selectors for this policy which will be used to negotiate the IPsec flows between the IKEv2 peers. During the negotiation, the peers may decide to narrow a flow to a subset of the configured traffic selector networks to match the policies on each side.

Each traffic selector will apply for packets with source address src and destination address dst. The keyword any will match any address (i.e. 0.0.0.0/0). If the src argument specifies a fictional source ID, the srcnat parameter can be used to specify the actual source address. This can be used in outgoing NAT/BINAT scenarios as described below.

The optional port modifiers restrict the traffic selectors to the specified ports. They are only valid in conjunction with the tcp(4) and udp(4) protocols. Ports can be specified by number or by name. For a list of all port name to number mappings, see the file /etc/services.

local localip Ic peer remote

The local parameter specifies the address or FQDN of the local endpoint. Unless the gateway is multi-homed or uses address aliases, this option is generally not needed.

The peer parameter specifies the address or FQDN of the remote endpoint. For host-to-host connections where dst is identical to remote, this option is generally not needed as it will be set to dst automatically. If it is not specified or if the keyword any is given, the default peer is used. Note that when these parameters are omitted, iked(8) will attempt to negotiate transport mode IPSec.

ikesa auth algorithm enc algorithm prf algorithm group group

These parameters define the mode and cryptographic transforms to be used for the IKE SA negotiation, also known as phase 1. The IKE SA will be used to authenticate the machines and to set up an encrypted channel for the IKEv2 protocol.

Possible values for auth, enc, prf, group, and the default proposals are described below in CRYPTO TRANSFORMS . If omitted, iked(8) will use the default proposals for the IKEv2 protocol.

childsa auth algorithm enc algorithm group group

These parameters define the cryptographic transforms to be used for the Child SA negotiation, also known as phase 2. Each Child SA will be used to negotiate the actual IPsec SAs. The initial Child SA is always negotiated with the initial IKEv2 key exchange; additional Child SAs may be negotiated with additional Child SA key exchanges for an established IKE SA.

Possible values for auth, enc, group, and the default proposals are described below in CRYPTO TRANSFORMS . If omitted, iked(8) will use the default proposals for the ESP or AH protocol. The group option will only be used to enable Perfect Forward Secrecy (PFS) for additional Child SAs exchanges that are not part of the initial key exchange.

srcid string Ic dstid string

srcid defines an ID of type ``FQDN'', ``ASN1_DN'', ``IPV4'', ``IPV6'', or ``UFQDN'' that will be used by iked(8) as the identity of the local peer. If the argument is an email address (reyk@example.com), iked(8) will use UFQDN as the ID type. The ASN1_DN type will be used if the string starts with a slash `/' (/C=DE/../CN=10.0.0.1/emailAddress=reyk@example.com). If the argument is an IPv4 address or a compressed IPv6 address, the ID types IPV4 or IPV6 will be used. Anything else is considered to be an FQDN.

If srcid is omitted, the default is to use the hostname of the local machine, see hostname(1) to set or print the hostname.

dstid is similar to srcid, but instead specifies the ID to be used by the remote peer.

ikelifetime time

The optional ikelifetime parameter defines the IKE SA expiration timeout by the time SA was created. A zero value disables active IKE SA rekeying. This is the default.

lifetime time [Ic bytes bytes]

The optional lifetime parameter defines the Child SA expiration timeout by the time SA was in use and by the number of bytes that were processed using the SA. Default values are 3 hours and 512 megabytes which means that SA will be rekeyed before reaching the time limit or 512 megabytes of data will pass through. Zero values disable rekeying.

Several unit specifiers are recognized (ignoring case): `m' and `h' for minutes and hours, and `K', `M' and `G' for kilo-, mega- and gigabytes accordingly.

Please note that rekeying must happen at least several times a day as IPsec security heavily depends on the frequent key renewals.

[ikeauth]

Specify the mode to mutually authenticate the peers. Non-psk modes will require to set up certificates and RSA public keys; see iked(8) for more information.

eap type

Use EAP to authenticate the initiator. The only supported EAP type is currently MSCHAP-V2. The responder will use RSA public key authentication.

psk string

Use a pre-shared key string or hex value (starting with 0x) for authentication.

rsa

Use RSA public key authentication. This is the default mode if no option is specified.

config option address

Send one or more optional configuration payloads (CP) to the peer. The configuration option can be one of the following with the expected address format:

address address

Assign a static address on the internal network.

address address/prefix

Assign a dynamic address on the internal network. The address will be assigned from an address pool with the size specified by prefix.

netmask netmask

The IPv4 netmask of the internal network.

name-server address

The DNS server address within the internal network.

netbios-server address

The NetBIOS name server (WINS) within the internal network. This option is provided for compatibility with legacy clients.

dhcp-server address

The address of an internal DHCP server for further configuration.

protected-subnet address/prefix

The address of the protected subnet within the internal network.

access-server address

The address of an internal remote access server.

tag string

Add a pf(4) tag to all packets of IPsec SAs created for this connection. This will allow matching packets for this connection by defining rules in pf.conf(5) using the tagged keyword.

The following variables can be used in tags to include information from the remote peer on runtime:

$id

The dstid that was proposed by the remote peer to identify itself. It will be expanded to id-value, e.g. FQDN/foo.example.com. To limit the size of the derived tag, iked(8) will extract the common name `CN=' from ASN1_DN IDs, for example ASN1_ID//C=DE/../CN=10.1.1.1/.. will be expanded to 10.1.1.1.

$domain

Extract the domain from IDs of type FQDN, UFQDN or ASN1_DN.

$name

The name of the IKEv2 policy that was configured in iked.conf or automatically generated by iked(8).

For example, if the ID is FQDN/foo.example.com or UFQDN/user@example.com, ``ipsec-$domain'' expands to ``ipsec-example.com''. The variable expansion for the tag directive occurs only at runtime, not during configuration file parse time.

tap interface

Send the decapsulated IPsec traffic to the specified enc(4) interface instead of enc0 for filtering and monitoring. The traffic will be blocked if the specified interface does not exist. This option is only valid with the operating system has or supports the enc(4) interface.

OUTGOING NETWORK ADDRESS TRANSLATION

For example, if the local subnet is 192.168.1.0/24 and all the traffic for a specific VPN peer should appear as coming from 10.10.10.1, the following configuration is used:

ikev2 esp from 10.10.10.1 (192.168.1.0/24) to 192.168.2.0/24 \
peer 10.10.20.1

From the peer's point of view, the local end of the VPN tunnel is declared to be 10.10.10.1 and all the traffic arrives with that source address.

CRYPTO TRANSFORMS

AuthenticationTa.IRKey LengthTa.IRTruncated Length

hmac-md5 Ta "128 bits" Ta "96 bits"

hmac-sha1 Ta "160 bits" Ta "96 bits"

hmac-sha2-256 Ta "256 bits" Ta "128 bits"

hmac-sha2-384 Ta "384 bits" Ta "192 bits"

hmac-sha2-512 Ta "512 bits" Ta "256 bits"

The following pseudo-random function types are permitted with the prf keyword:

PRFTa.IRKey LengthTa

hmac-md5 Ta "128 bits" Ta "[IKE only]"

hmac-sha1 Ta "160 bits" Ta "[IKE only]"

hmac-sha2-256 Ta "256 bits" Ta "[IKE only]"

hmac-sha2-384 Ta "384 bits" Ta "[IKE only]"

hmac-sha2-512 Ta "512 bits" Ta "[IKE only]"

The following cipher types are permitted with the enc keyword:

CipherTa.IRKey LengthTa

3des Ta "168 bits" Ta ""

aes-128 Ta "128 bits" Ta ""

aes-192 Ta "192 bits" Ta ""

aes-256 Ta "256 bits" Ta ""

aes-128-ctr Ta "160 bits" Ta "[ESP only]"

aes-192-ctr Ta "224 bits" Ta "[ESP only]"

aes-256-ctr Ta "288 bits" Ta "[ESP only]"

aes-128-gcm Ta "160 bits" Ta "[ESP only]"

aes-192-gcm Ta "224 bits" Ta "[ESP only]"

aes-256-gcm Ta "288 bits" Ta "[ESP only]"

blowfish Ta "160 bits" Ta "[ESP only]"

cast Ta "128 bits" Ta "[ESP only]"

chacha20-poly1305 Ta "288 bits" Ta "[ESP only]"

The following cipher types provide only authentication, not encryption:

aes-128-gmac Ta "160 bits" Ta "[ESP only]"

aes-192-gmac Ta "224 bits" Ta "[ESP only]"

aes-256-gmac Ta "288 bits" Ta "[ESP only]"

null Ta "" Ta "[ESP only]"

3DES requires 24 bytes to form its 168-bit key. This is because the most significant bit of each byte is used for parity.

The keysize of AES-CTR is actually 128-bit. However as well as the key, a 32-bit nonce has to be supplied. Thus 160 bits of key material have to be supplied. The same applies to AES-GCM, AES-GMAC and Chacha20-Poly1305, however in the latter case the keysize is 256 bit.

Using AES-GMAC or NULL with ESP will only provide authentication. This is useful in setups where AH cannot be used, e.g. when NAT is involved.

The following group types are permitted with the group keyword:

NameTa.IRGroupTa.IRSizeTa.IRType

modp768 Ta grp1 Ta 768 Ta "MODP"

modp1024 Ta grp2 Ta 1024 Ta "MODP"

ec2n155 Ta grp3 Ta 155 Ta "EC2N [insecure]"

ec2n185 Ta grp4 Ta 185 Ta "EC2N [insecure]"

modp1536 Ta grp5 Ta 1536 Ta "MODP"

modp2048 Ta grp14 Ta 2048 Ta "MODP"

modp3072 Ta grp15 Ta 3072 Ta "MODP"

modp4096 Ta grp16 Ta 4096 Ta "MODP"

modp6144 Ta grp17 Ta 6144 Ta "MODP"

modp8192 Ta grp18 Ta 8192 Ta "MODP"

ecp256 Ta grp19 Ta 256 Ta "ECP"

ecp384 Ta grp20 Ta 384 Ta "ECP"

ecp521 Ta grp21 Ta 521 Ta "ECP"

modp1024-160 Ta grp22 Ta 2048 Ta "MODP, 160 bit Prime Order Subgroup"

modp2048-224 Ta grp23 Ta 2048 Ta "MODP, 224 bit Prime Order Subgroup"

modp2048-256 Ta grp24 Ta 2048 Ta "MODP, 256 bit Prime Order Subgroup"

ecp192 Ta grp25 Ta 192 Ta "ECP"

ecp224 Ta grp26 Ta 224 Ta "ECP"

brainpool224 Ta grp27 Ta 224 Ta "ECP, brainpoolP224r1"

brainpool256 Ta grp28 Ta 256 Ta "ECP, brainpoolP256r1"

brainpool384 Ta grp29 Ta 384 Ta "ECP, brainpoolP384r1"

brainpool512 Ta grp30 Ta 512 Ta "ECP, brainpoolP512r1"

curve25519 Ta - Ta 256 Ta "Curve25519"

The currently supported group types are either MODP (exponentiation groups modulo a prime), EC2N (elliptic curve groups over GF[2^N]), ECP (elliptic curve groups modulo a prime), or the non-standard Curve25519. Please note that the EC2N groups are considered as insecure and only provided for backwards compatibility.

EXAMPLES

user "test" "password123"

ikev2 "win7" esp \
from 0.0.0.0/0 to 172.16.2.0/24 \
peer 10.0.0.0/8 local 192.168.56.0/24 \
eap "mschap-v2" \
config address 172.16.2.1 \
tag "$name-$id"

The next example allows peers to authenticate using a pre-shared key `foobar' :

ikev2 "big test" \
esp proto tcp \
from 10.0.0.0/8 port 23 to 20.0.0.0/8 port 40 \
from 192.168.1.1 to 192.168.2.2 \
peer any local any \
ikesa enc 3des auth hmac-sha1 group modp1024 \
childsa enc aes-128 auth hmac-sha1 \
srcid host.example.com \
dstid 192.168.0.254 \
psk "foobar"

The following example illustrates the last matching policy evaluation for incoming connections on an IKEv2 gateway. The peer 192.168.1.34 will always match the first policy because of the quick keyword; connections from the peers 192.168.1.3 and 192.168.1.2 will be matched by one of the last two policies; any other connections from 192.168.1.0/24 will be matched by the `subnet' policy; and any other connection will be matched by the `catch' all policy.

ikev2 quick esp from 10.10.10.0/24 to 10.20.20.0/24 \
peer 192.168.1.34
ikev2 "catch all" esp from 10.0.1.0/24 to 10.0.2.0/24 \
peer any
ikev2 "subnet" esp from 10.0.3.0/24 to 10.0.4.0/24 \
peer 192.168.1.0/24
ikev2 esp from 10.0.5.0/30 to 10.0.5.4/30 peer 192.168.1.2
ikev2 esp from 10.0.5.8/30 to 10.0.5.12/30 peer 192.168.1.3

SEE ALSO

HISTORY

AUTHORS

Reyk Floeter <Mt reyk@openbsd.org ,> with modifications and enhancements by

Marcel Moolenaar <Mt marcel@FreeBSD.org .>