ISAKMPD(8) OpenBSD System Manager's Manual ISAKMPD(8)
isakmpd - ISAKMP/Oakley a.k.a. IKEv1 key management daemon
isakmpd [-46adKLnSTv] [-c config-file] [-D class=level] [-f fifo]
[-i pid-file] [-l packetlog-file] [-N udpencap-port]
[-p listen-port] [-R report-file]
The isakmpd daemon establishes security associations for encrypted and/or
authenticated network traffic. At this moment, and probably forever,
this means ipsec(4) traffic. Traditionally, isakmpd was configured using
the isakmpd.conf(5) file format. A newer, much simpler format is now
isakmpd implements the IKEv1 protocol which is defined in the standards
ISAKMP/Oakley (RFC 2408), IKE (RFC 2409), and the Internet DOI (RFC
2407). The newer IKEv2 protocol, as defined in RFC 4306, is not
supported by isakmpd but by iked(8). It follows then that references to
IKE in this document pertain to IKEv1 only, and not IKEv2.
The way isakmpd goes about its work is by maintaining an internal
configuration as well as a policy database which describes what kinds of
SAs to negotiate, and by listening for different events that trigger
these negotiations. The events that control isakmpd consist of
negotiation initiations from a remote party, user input via a FIFO or by
signals, upcalls from the kernel via a PF_KEY socket, and lastly by
scheduled events triggered by timers running out.
Most uses of isakmpd will be to implement so called "virtual private
networks" (VPNs). The ability to provide redundancy is made available
through carp(4) and sasyncd(8). For other uses, some more knowledge of
IKEv1 as a protocol is required. The RFCs mentioned below are a possible
On startup isakmpd forks into two processes for privilege separation.
The unprivileged child jails itself with chroot(8) to /var/empty. The
privileged process communicates with the child, reads configuration files
and PKI information, and binds to privileged ports on its behalf. See
the CAVEATS section below.
The options are as follows:
-4 | -6
These options control what address family (AF_INET and/or
AF_INET6) isakmpd will use. The default is to use both IPv4 and
-a If given, isakmpd does not set up flows automatically. Instead
manual flows may be configured using ipsec.conf(5) or by programs
such as bgpd(8). Thus isakmpd only takes care of SA
If given, the -c option specifies an alternate configuration file
instead of /etc/isakmpd/isakmpd.conf. As this file may contain
sensitive information, it must be readable only by the user
running the daemon. isakmpd will reread the configuration file
when sent a SIGHUP signal.
Note that this option applies only to configuration files in the
isakmpd.conf(5) format, not those in the ipsec.conf(5) format.
Debugging class. It's possible to specify this argument many
times. It takes a parameter of the form class=level, where both
class and level are numbers. class denotes a debugging class,
and level the level you want that debugging class to limit debug
printouts at (i.e. all debug printouts above the level specified
will not output anything). If class is set to `A', then all
debugging classes are set to the specified level.
Valid values for class are as follows:
10 FIFO user interface
Currently used values for level are 0 to 99.
-d The -d option is used to make the daemon run in the foreground,
logging to stderr.
The -f option specifies the FIFO (a.k.a. named pipe) where the
daemon listens for user requests. If the path given is a dash
(`-'), isakmpd will listen to stdin instead.
By default the PID of the daemon process will be written to
/var/run/isakmpd.pid. This path can be overridden by specifying
another one as the argument to the -i option. Note that only
paths beginning with /var/run are allowed.
-K When this option is given, isakmpd does not read the policy
configuration file and no keynote(4) policy check is
accomplished. This option can be used when policies for flows
and SA establishment are arranged by other programs like
ipsecctl(8) or bgpd(8).
-L Enable IKE packet capture. When this option is given, isakmpd
will write an unencrypted copy of the negotiation packets it is
sending and receiving to the file /var/run/isakmpd.pcap, which
can later be read by tcpdump(8) and other utilities using
As option -L above, but capture to a specified file. Note that
only paths beginning with /var/run are allowed.
The -N option specifies the listen port for encapsulated UDP that
the daemon will bind to.
-n When the -n option is given, the kernel will not take part in the
negotiations. This is a non-destructive mode, so to speak, in
that it won't alter any SAs in the IPsec stack.
The -p option specifies the listen port the daemon will bind to.
When you signal isakmpd a SIGUSR1, it will report its internal
state to a report file, normally /var/run/isakmpd.report, but
this can be changed by feeding the file name as an argument to
the -R flag. Note that only paths beginning with /var/run are
-S This option is used for setups using sasyncd(8) and carp(4) to
provide redundancy. isakmpd starts in passive mode and will not
initiate any connections or process any incoming traffic until
sasyncd has determined that the host is the carp master.
Additionally, isakmpd will not delete SAs on shutdown by sending
delete messages to all peers.
-T When this option is given, NAT-Traversal will be disabled and
isakmpd will not advertise support for NAT-Traversal to its
-v Enables verbose logging. Normally, isakmpd is silent and outputs
only messages when a warning or an error occurs. With verbose
logging isakmpd reports successful completion of phase 1 (Main
and Aggressive) and phase 2 (Quick) exchanges (Information and
Transaction exchanges do not generate any additional status
THE FIFO USER INTERFACE
When isakmpd starts, it creates a FIFO (named pipe) where it listens for
user requests. All commands start with a single letter, followed by
command-specific options. Available commands are:
C add [section]:tag=value
C rmv [section]:tag=value
C rm [section]:tag
C rms [section]
C set [section]:tag=value
C set [section]:tag=value force
Update the running isakmpd configuration atomically. `set' sets
a configuration value consisting of a section, tag, and value
triplet. `set' will fail if the configuration already contains a
section with the named tag; use the `force' option to change this
behaviour. `add' appends a configuration value to the named
configuration list tag, unless the value is already in the list.
`rm' removes a tag in a section. `rms' removes an entire
section. `rmv' removes an entry from a list, thus reversing an
NOTE: Sending isakmpd a SIGHUP or an "R" through the FIFO will
void any updates done to the configuration.
C get [section]:tag
Get the configuration value of the specified section and tag.
The result is stored in /var/run/isakmpd.result.
Start the named connection, if stopped or inactive.
D <class> <level>
D A <level>
D T Set debug class <class> to level <level>. If <class> is
specified as `A', the level applies to all debug classes. D T
toggles all debug classes to level zero. Another D T command
will toggle them back to the earlier levels.
d <cookies> <msgid>
Delete the specified SA from the system. Specify <msgid> as `-'
to match a Phase 1 SA.
Set isakmpd to active or passive mode. In passive mode no
packets are sent to peers.
p off Enable or disable cleartext IKE packet capture. When enabling,
optionally specify which file isakmpd should capture the packets
to (the default is /var/run/isakmpd.pcap). Note that only paths
beginning with /var/run are allowed.
Q Cleanly shutdown the daemon, as when sent a SIGTERM signal.
R Reinitialize isakmpd, as when sent a SIGHUP signal.
r Report isakmpd internal state to a file. See the -R option.
Same as when sent a SIGUSR1 signal.
S Report information on all known SAs to the
T Tear down all active quick mode connections.
t [<phase>] <name>
Tear down the named connection, if active. For name, the tag
specified in isakmpd.conf(5) or the IP address of the remote host
can be used. The optional parameter phase specifies whether to
delete a phase 1 or phase 2 SA. The value `main' indicates a
phase 1 connection; the value `quick' a phase 2 connection. If
no phase is specified, `quick' will be assumed.
SETTING UP AN IKE PUBLIC KEY INFRASTRUCTURE (PKI)
In order to use public key based authentication, there has to be an
infrastructure managing the key signing. Either there is an already
existing PKI isakmpd should take part in, or there will be a need to set
one up. The procedures for using a pre-existing PKI varies depending on
the actual Certificate Authority (CA) used, and is therefore not covered
here, other than mentioning that openssl(1) needs to be used to create a
Certificate Signing Request (CSR) that the CA understands.
A number of methods exist to allow authentication:
This method does not use keys at all, but relies on a shared
Public keys are used to authenticate. See PUBLIC KEY
X.509 Certificates are used to authenticate. See X.509
Keynote Certificates are used to authenticate. See KEYNOTE
When configuring isakmpd for key- and certificate-based authentication,
the ``Transforms'' tag in isakmpd.conf(5) should include ``RSA_SIG''.
For example, the transform ``3DES-SHA-RSA_SIG'' means: 3DES encryption,
SHA hash, authentication using RSA signatures.
PUBLIC KEY AUTHENTICATION
It is possible to store trusted public keys to make them directly usable
by isakmpd, bypassing the need to use certificates. The keys should be
saved in PEM format (see openssl(1)) and named and stored after this easy
For IPv4 identities: /etc/isakmpd/pubkeys/ipv4/A.B.C.D
For IPv6 identities: /etc/isakmpd/pubkeys/ipv6/abcd:abcd::ab:bc
For FQDN identities: /etc/isakmpd/pubkeys/fqdn/foo.bar.org
For UFQDN identities: /email@example.com
Depending on the ID-type field of isakmpd.conf(5), keys may be named
after their IPv4 address (IPV4_ADDR or IPV4_ADDR_SUBNET), IPv6 address
(IPV6_ADDR or IPV6_ADDR_SUBNET), fully qualified domain name (FDQN), user
fully qualified domain name (USER_FQDN), or key ID (KEY_ID).
For example, isakmpd can authenticate using the pre-generated keys if the
local public key, by default /etc/isakmpd/local.pub, is copied to the
remote gateway as /etc/isakmpd/pubkeys/ipv4/local.gateway.ip.address and
the remote gateway's public key is copied to the local gateway as
/etc/isakmpd/pubkeys/ipv4/remote.gateway.ip.address. Of course, new keys
may also be generated (the user is not required to use the pre-generated
keys). In this example, ID-type would also have to be set to IPV4_ADDR
or IPV4_ADDR_SUBNET in isakmpd.conf(5).
X.509 is a framework for public key certificates. Certificates can be
generated using openssl(1) and provide a means for PKI authentication.
In the following example, a CA is created along with host certificates to
be signed by the CA.
1. Create your own Certificate Authority (CA).
Create a self-signed root certificate. The CA certificate is named
ca.crt, and its private key ca.key:
# openssl req -x509 -days 365 -newkey rsa:2048 \
-keyout /etc/ssl/private/ca.key \
openssl req will prompt for information that will be incorporated
into the certificate request. The information entered comprises a
Distinguished Name (DN). There are quite a few fields, but some can
be left blank. For some fields there will be a default value; if
`.' is entered, the field will be left blank.
2. Create Certificate Signing Requests (CSRs) for IKE peers. The CSRs
are signed with a pre-generated private key.
This step, as well as the next one, needs to be done for every peer.
Furthermore the last step will need to be done once for each ID you
want the peer to have. The 10.0.0.1 below symbolizes that ID, in
this case an IPv4 ID, and should be changed for each invocation.
You will be asked for a DN for each run. Encoding the ID in the
common name is recommended, as it should be unique.
# openssl req -new -key /etc/isakmpd/private/local.key \
Now take these certificate signing requests to your CA and process
them as below. A subjectAltName extension field should be added to
the certificate. Replace 10.0.0.1 with the IP address which isakmpd
will use as the certificate identity.
# env CERTIP=10.0.0.1 openssl x509 -req \
-days 365 -in 10.0.0.1.csr \
-CA /etc/ssl/ca.crt -CAkey /etc/ssl/private/ca.key \
-CAcreateserial -extfile /etc/ssl/x509v3.cnf \
-extensions x509v3_IPAddr -out 10.0.0.1.crt
For a FQDN certificate, do:
# env CERTFQDN=somehost.somedomain openssl x509 -req \
-days 365 -in somehost.somedomain.csr \
-CA /etc/ssl/ca.crt -CAkey /etc/ssl/private/ca.key \
-CAcreateserial -extfile /etc/ssl/x509v3.cnf \
-extensions x509v3_FQDN -out somehost.somedomain.crt
If CERTFQDN is being used, make sure that the subjectAltName field
of the certificate is specified using srcid in ipsec.conf(5). A
similar setup will be required if isakmpd.conf(5) is being used
Put the certificate (the file ending in .crt) in /etc/isakmpd/certs/
on your local system. Also carry over the CA cert /etc/ssl/ca.crt
and put it in /etc/isakmpd/ca/.
To revoke certificates, create a Certificate Revocation List (CRL) file
and install it in the /etc/isakmpd/crls/ directory. See openssl(1) and
the `crl' subcommand for more info.
Keynote is a trust-management framework. Keys can be generated using
keynote(1) and provide an alternative means for isakmpd to authenticate.
See keynote(4) for further information.
The directory where CA certificates are kept.
The directory where IKE certificates are kept, both the local
certificate(s) and those of the peers, if a choice to have them
kept permanently has been made.
The directory where CRLs are kept.
The configuration file. As this file can contain sensitive
information it must not be readable by anyone but the user
The keynote policy configuration file. The same mode
requirements as isakmpd.conf.
The directory where KeyNote credentials are kept.
The directory where local private keys used for public key
authentication are kept. By default, the system startup script
rc(8) generates a key-pair when starting, if one does not already
exist. The entire keypair is in local.key, and a copy of the
public key suitable for transferring to other hosts is extracted
into /etc/isakmpd/local.pub. There has to be a certificate for
local.key in the certificate directory, /etc/isakmpd/certs/.
local.key has the same mode requirements as isakmpd.conf.
The directory in which trusted public keys are kept. The keys
must be named in the fashion described above.
The FIFO used to manually control isakmpd.
The default IKE packet capture file.
The PID of the current daemon.
The report file written when SIGUSR1 is received.
The report file written when the `S' or `C get' command is issued
in the command FIFO.
openssl(1), getnameinfo(3), pcap(3), ipsec(4), ipsec.conf(5),
isakmpd.conf(5), isakmpd.policy(5), iked(8), sasyncd(8), ssl(8),
The ISAKMP/Oakley key management protocol is described in RFC 2407, RFC
2408, and RFC 2409. NAT-Traversal is described in RFC 3947. This
implementation was done 1998 by Niklas Hallqvist and Niels Provos,
sponsored by Ericsson Radio Systems.
When storing a trusted public key for an IPv6 identity, the most
efficient form of address representation, i.e. "::" instead of ":0:0:0:",
must be used or the matching will fail. isakmpd uses the output from
getnameinfo(3) for the address-to-name translation. The privileged
process only allows binding to the default port 500 or unprivileged ports
(>1024). It is not possible to change the interfaces isakmpd listens on
without a restart.
For redundant setups, sasyncd(8) must be manually restarted every time
isakmpd is restarted.
OpenBSD 5.1 September 29, 2011 OpenBSD 5.1
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