sbin/isakmpd/isakmpd.8

.\" $OpenBSD: isakmpd.8,v 1.123 2019/08/30 17:51:47 jmc Exp $
.\" $EOM: isakmpd.8,v 1.23 2000/05/02 00:30:23 niklas Exp $
.\"
.\" Copyright (c) 1998, 1999, 2000, 2001 Niklas Hallqvist.
.\" All rights reserved.
.\" Copyright (c) 1999 Angelos D. Keromytis.  All rights reserved.
.\" Copyright (c) 2001, 2002 H�kan Olsson.  All rights reserved.
.\"
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" This code was written under funding by Ericsson Radio Systems.
.\"
.\" Manual page, using -mandoc macros
.\"
.Dd $Mdocdate: August 30 2019 $
.Dt ISAKMPD 8
.Os
.Sh NAME
.Nm isakmpd
.Nd ISAKMP/Oakley a.k.a. IKEv1 key management daemon
.Sh SYNOPSIS
.Nm isakmpd
.Op Fl 46adKLnSTv
.Op Fl c Ar config-file
.Op Fl D Ar class Ns = Ns Ar level
.Op Fl f Ar fifo
.Op Fl i Ar pid-file
.Op Fl l Ar packetlog-file
.Op Fl N Ar udpencap-port
.Op Fl p Ar listen-port
.Op Fl R Ar report-file
.Sh DESCRIPTION
The
.Nm
daemon establishes Security Associations (SAs) for encrypted
and/or authenticated network traffic.
At this moment, and probably forever, this means
.Xr ipsec 4
traffic.
Traditionally,
.Nm
was configured using the
.Xr isakmpd.conf 5
file format.
A newer, much simpler format is now available:
.Xr ipsec.conf 5 .
.Pp
.Nm
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 5996,
is not supported by
.Nm
but by
.Xr iked 8 .
It follows then that references to IKE in this document
pertain to IKEv1 only,
and not IKEv2.
.Pp
The way
.Nm
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
.Nm
consist of negotiation initiations from a remote party, user input via
a FIFO or by signals, upcalls from the kernel via a
.Dv PF_KEY
socket, and lastly by scheduled events triggered by timers running out.
.Pp
Most uses of
.Nm
will be to implement so called "virtual private networks" (VPNs).
The ability to provide redundancy is made available through
.Xr carp 4
and
.Xr sasyncd 8 .
For other uses, some more knowledge of IKEv1 as a protocol is required.
The RFCs mentioned below are a possible starting point.
.Pp
On startup
.Nm
forks into two processes for privilege separation.
The unprivileged child jails itself with
.Xr chroot 8
to
.Pa /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
.Sx CAVEATS
section below.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl 4 | 6
These options control what address family
.Pf ( Dv AF_INET
and/or
.Dv AF_INET6 )
.Nm
will use.
The default is to use both IPv4 and IPv6.
.It Fl a
If given,
.Nm
does not set up flows automatically.
Instead manual flows may be configured using
.Xr ipsec.conf 5
or by programs such as
.Xr bgpd 8 .
Thus
.Nm
only takes care of SA establishment.
.It Fl c Ar config-file
If given, the
.Fl c
option specifies an alternate configuration file instead of
.Pa /etc/isakmpd/isakmpd.conf .
As this file may contain sensitive information, it must be readable
only by the user running the daemon.
.Nm
will reread the configuration file when sent a
.Dv SIGHUP
signal.
.Pp
Note that this option applies only to configuration files in the
.Xr isakmpd.conf 5
format, not those in the
.Xr ipsec.conf 5
format.
.It Fl D Ar class Ns = Ns Ar level
Debugging class.
It's possible to specify this argument many times.
It takes a parameter of the form
.Ar class Ns = Ns Ar level ,
where both
.Ar class
and
.Ar level
are numbers.
.Ar class
denotes a debugging class, and
.Ar 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
.Ar class
is set to
.Sq A ,
then all debugging classes are set to the specified level.
.Pp
Valid values for
.Ar class
are as follows:
.Pp
.Bl -tag -width 2n -offset indent -compact
.It 0
Misc
.It 1
Transport
.It 2
Message
.It 3
Crypto
.It 4
Timer
.It 5
Sysdep
.It 6
SA
.It 7
Exchange
.It 8
Negotiation
.It 9
Policy
.It 10
FIFO user interface
.It A
All
.El
.Pp
Currently used values for
.Ar level
are 0 to 99.
.It Fl d
The
.Fl d
option is used to make the daemon run in the foreground, logging to stderr.
.It Fl f Ar fifo
The
.Fl f
option specifies the FIFO
(a.k.a. named pipe) where the daemon listens for
user requests.
If the path given is a dash
.Pq Sq \&- ,
.Nm
will listen to stdin instead.
.It Fl i Ar pid-file
By default the PID of the daemon process will be written to
.Pa /var/run/isakmpd.pid .
This path can be overridden by specifying another one as the argument to the
.Fl i
option.
Note that only paths beginning with
.Pa /var/run
are allowed.
.It Fl K
When this option is given,
.Nm
does not read the policy configuration file and no
.Xr keynote 4
policy check is accomplished.
This option can be used when policies for flows and SA establishment are
arranged by other programs like
.Xr ipsecctl 8
or
.Xr bgpd 8 .
.It Fl L
Enable IKE packet capture.
When this option is given,
.Nm
will write an unencrypted copy of the negotiation packets it
is sending and receiving to the file
.Pa /var/run/isakmpd.pcap ,
which can later be read by
.Xr tcpdump 8
and other utilities using
.Xr pcap_open_offline 3 .
.It Fl l Ar packetlog-file
As option
.Fl L
above, but capture to a specified file.
Note that only paths beginning with
.Pa /var/run
are allowed.
.It Fl N Ar udpencap-port
The
.Fl N
option specifies the listen port for encapsulated UDP
that the daemon will bind to.
.It Fl n
When the
.Fl 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.
.It Fl p Ar listen-port
The
.Fl p
option specifies the listen port the daemon will bind to.
.It Fl R Ar report-file
When you signal
.Nm
a
.Dv SIGUSR1 ,
it will report its internal state to a report file, normally
.Pa /var/run/isakmpd.report ,
but this can be changed by feeding
the file name as an argument to the
.Fl R
flag.
Note that only paths beginning with
.Pa /var/run
are allowed.
.It Fl S
This option is used for setups using
.Xr sasyncd 8
and
.Xr carp 4
to provide redundancy.
.Nm
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,
.Nm
will not delete SAs on shutdown
by sending delete messages to all peers.
.It Fl T
When this option is given, NAT-Traversal will be disabled and
.Nm
will not advertise support for NAT-Traversal to its peers.
.It Fl v
Enables verbose logging.
Normally,
.Nm
is silent and outputs only messages when a warning or an error occurs.
With verbose logging
.Nm
reports successful completion of phase 1 (Main and Aggressive) and phase 2
(Quick) exchanges (Information and Transaction exchanges do not generate any
additional status information).
.El
.Sh THE FIFO USER INTERFACE
When
.Nm
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:
.Pp
.Bl -tag -width Ds -compact
.It Ic C add Oo Ar section Oc : Ns Ar tag Ns = Ns Ar value
.It Ic C rmv Oo Ar section Oc : Ns Ar tag Ns = Ns Ar value
.It Ic C rm Oo Ar section Oc : Ns Ar tag
.It Ic C rms Op Ar section
.It Ic C set Oo Ar section Oc : Ns Ar tag Ns = Ns Ar value Op Ic force
Update the running
.Nm
configuration atomically.
.Sq set
sets a configuration value consisting of a section, tag, and value triplet.
.Sq set
will fail if the configuration already contains a section with the named tag;
use the
.Sq force
option to change this behaviour.
.Sq add
appends a configuration value to the named configuration list tag,
unless the value is already in the list.
.Sq rm
removes a tag in a section.
.Sq rms
removes an entire section.
.Sq rmv
removes an entry from a list, thus reversing an
.Sq add
operation.
.Pp
NOTE: Sending
.Nm
a
.Dv SIGHUP
or an "R" through the FIFO will void any updates done to the configuration.
.Pp
.It Ic C get Oo Ar section Oc : Ns Ar tag
Get the configuration value of the specified section and tag.
The result is stored in
.Pa /var/run/isakmpd.result .
.Pp
.It Ic c Ar name
Start the named connection, if stopped or inactive.
.Pp
.It Ic D Ar class level
.It Ic D A Ar level
.It Ic D T
Set debug class
.Ar class
to level
.Ar level .
If
.Ar class
is specified as
.Sq A ,
the level applies to all debug classes.
.Ic D T
toggles all debug classes to level zero.
Another
.Ic D T
command will toggle them back to the earlier levels.
.Pp
.It Ic d Ar cookies msgid
Delete the specified SA from the system.
Specify
.Ar msgid
as
.Sq -
to match a Phase 1 SA.
.Pp
.It Ic M active
.It Ic M passive
Set
.Nm
to active or passive mode.
In passive mode no packets are sent to peers.
.Pp
.It Ic p on Ns Op = Ns Ar path
.It Ic p off
Enable or disable cleartext IKE packet capture.
When enabling, optionally specify which file
.Nm
should capture the packets to
(the default is
.Pa /var/run/isakmpd.pcap ) .
Note that only paths beginning with
.Pa /var/run
are allowed.
.Pp
.It Ic Q
Cleanly shutdown the daemon, as when sent a
.Dv SIGTERM
signal.
.Pp
.It Ic R
Reinitialize
.Nm isakmpd ,
as when sent a
.Dv SIGHUP
signal.
.Pp
.It Ic r
Report
.Nm
internal state to
.Xr syslog 3 .
See the
.Fl R
option.
Same as when sent a
.Dv SIGUSR1
signal.
.Pp
.It Ic S
Report information on all known SAs to the
.Pa /var/run/isakmpd.result
file.
.Pp
.It Ic T
Tear down all active quick mode connections.
.Pp
.It Ic t Oo Ar phase Oc Ar name
Tear down the named connection, if active.
For
.Ar name ,
the tag specified in
.Xr isakmpd.conf 5
or the IP address of the remote host can be used.
The optional parameter
.Ar phase
specifies whether to delete a phase 1 or phase 2 SA.
The value
.Sq main
indicates a phase 1 connection;
the value
.Sq quick
a phase 2 connection.
If no phase is specified,
.Sq quick
will be assumed.
.El
.Sh 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
.Nm
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
.Xr openssl 1
needs to be used to create a Certificate Signing Request (CSR) that the
CA understands.
.Pp
A number of methods exist to allow authentication:
.Bl -ohang -offset indent
.It Passphrase:
This method does not use keys at all, but relies on a shared passphrase.
.It Host Keys:
Public keys are used to authenticate.
See
.Sx PUBLIC KEY AUTHENTICATION
below.
.It X.509 Certificates:
X.509 Certificates are used to authenticate.
See
.Sx X.509 AUTHENTICATION
below.
.It Keynote Certificates:
Keynote Certificates are used to authenticate.
See
.Sx KEYNOTE AUTHENTICATION
below.
.El
.Pp
When configuring
.Nm
for key- and certificate-based authentication,
the
.Dq Transforms
tag in
.Xr isakmpd.conf 5
should include
.Dq RSA_SIG .
For example, the transform
.Dq 3DES-SHA-RSA_SIG
means:
3DES encryption, SHA hash, authentication using RSA signatures.
.Sh PUBLIC KEY AUTHENTICATION
It is possible to store trusted public keys to make them directly
usable by
.Nm ,
bypassing the need to use certificates.
The keys should be saved in PEM format (see
.Xr openssl 1 )
and named and stored after this easy formula:
.Pp
.Bl -tag -width "for_ufqdn_identitiesXX" -offset 3n -compact
.It For IPv4 identities:
.Pa /etc/isakmpd/pubkeys/ipv4/A.B.C.D
.It For IPv6 identities:
.Pa /etc/isakmpd/pubkeys/ipv6/abcd:abcd::ab:bc
.It For FQDN identities:
.Pa /etc/isakmpd/pubkeys/fqdn/foo.bar.org
.It For UFQDN identities:
.Pa /etc/isakmpd/pubkeys/ufqdn/user@foo.bar.org
.El
.Pp
Depending on the
.Dv ID-type
field of
.Xr 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).
.Pp
For example,
.Nm
can authenticate using the pre-generated keys if the local public key,
by default
.Pa /etc/isakmpd/local.pub ,
is copied to the remote gateway as
.Pa /etc/isakmpd/pubkeys/ipv4/local.gateway.ip.address
and the remote gateway's public key
is copied to the local gateway as
.Pa /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,
.Dv ID-type
would also have to be set to IPV4_ADDR or IPV4_ADDR_SUBNET
in
.Xr isakmpd.conf 5 .
.Sh X.509 AUTHENTICATION
X.509 is a framework for public key certificates.
Certificates can be generated using
.Xr 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.
.Bl -enum
.It
Create your own Certificate Authority (CA).
.Pp
First, create a private key for the CA, and a Certificate Signing Request
(CSR) to enable the CA to sign its own key:
.Bd -literal -offset indent
# openssl genrsa -out /etc/ssl/private/ca.key 2048
# openssl req -new -key /etc/ssl/private/ca.key \e
	-out /etc/ssl/private/ca.csr
.Ed
.Pp
.Ic 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
.Sq \&.
is entered, the field will be left blank.
.Pp
After the CSR has been generated, it is used to create and sign
a certificate for the CA:
.Bd -literal -offset indent
# openssl x509 -req -days 365 -in /etc/ssl/private/ca.csr \e
	-signkey /etc/ssl/private/ca.key \e
	-extfile /etc/ssl/x509v3.cnf -extensions x509v3_CA \e
	-out /etc/ssl/ca.crt
.Ed
.It
Create Certificate Signing Requests (CSRs) for IKE peers.
The CSRs are signed with a pre-generated private key.
.Pp
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.
A fully qualified domain name (FQDN) may be used instead of an IPv4 ID.
You will be asked for a DN for each run.
Encoding the ID in the common name is recommended, as it should be unique.
.Bd -literal -offset indent
# openssl req -new -key /etc/isakmpd/private/local.key \e
	-out /etc/isakmpd/private/10.0.0.1.csr
.Ed
.Pp
Now take these certificate signing requests to your CA and process
them as below.
A configuration file is used to add a
.Em subjectAltName
extension field matching the ID used by
.Nm
to the certificate.
.Pp
If using an IPv4 ID, copy
.Pa /etc/ssl/x509v3.cnf
to a temporary file and edit it to replace
.Dv $ENV::CERTIP
with the IP address (10.0.0.1 in this example), then generate a signed
certificate:
.Bd -literal -offset indent
# sed 's,\\$ENV::CERTIP,10.0.0.1,' \e
	< /etc/ssl/x509v3.cnf > ~/tmp_x509v3.cnf
# openssl x509 -req \e
	-days 365 -in 10.0.0.1.csr \e
	-CA /etc/ssl/ca.crt -CAkey /etc/ssl/private/ca.key \e
	-CAcreateserial -extfile ~/tmp_x509v3.cnf \e
	-extensions x509v3_IPAddr -out 10.0.0.1.crt
.Ed
.Pp
For an FQDN certificate, replace
.Dv $ENV::CERTFQDN
with the hostname and generate a signed certificate:
.Bd -literal -offset indent
# sed 's,\\$ENV::CERTFQDN,somehost.somedomain,' \e
	< /etc/ssl/x509v3.cnf > ~/tmp_x509v3.cnf
# openssl x509 -req \e
	-days 365 -in somehost.somedomain.csr \e
	-CA /etc/ssl/ca.crt -CAkey /etc/ssl/private/ca.key \e
	-CAcreateserial -extfile ~/tmp_x509v3.cnf \e
	-extensions x509v3_FQDN -out somehost.somedomain.crt
.Ed
.Pp
If CERTFQDN is being used,
make sure that the
.Va subjectAltName
field of the certificate is specified using
.Ic srcid
in
.Xr ipsec.conf 5 .
A similar setup will be required if
.Xr isakmpd.conf 5
is being used instead.
.Pp
Put the certificate (the file ending in .crt) in
.Pa /etc/isakmpd/certs/
on your local system.
Also carry over the CA cert
.Pa /etc/ssl/ca.crt
and put it in
.Pa /etc/isakmpd/ca/ .
.El
.Pp
To revoke certificates, create a Certificate Revocation List (CRL) file
and install it in the
.Pa /etc/isakmpd/crls/
directory.
See
.Xr openssl 1
and the
.Sq crl
subcommand for more info.
.Sh KEYNOTE AUTHENTICATION
Keynote is a trust-management framework.
Keys can be generated using
.Xr keynote 1
and provide an alternative means for
.Nm
to authenticate.
See
.Xr keynote 4
for further information.
.Sh FILES
.Bl -tag -width Ds
.It Pa /etc/isakmpd/ca/
The directory where CA certificates are kept.
.It Pa /etc/isakmpd/certs/
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.
.It Pa /etc/isakmpd/crls/
The directory where CRLs are kept.
.It Pa /etc/isakmpd/isakmpd.conf
The configuration file.
As this file can contain sensitive information
it must not be readable by anyone but the user running
.Nm .
.It Pa /etc/isakmpd/isakmpd.policy
The keynote policy configuration file.
The same mode requirements as
.Pa isakmpd.conf .
.It Pa /etc/isakmpd/keynote/
The directory where KeyNote credentials are kept.
.It Pa /etc/isakmpd/private/
The directory where local private keys used for public key authentication
are kept.
By default, the system startup script
.Xr rc 8
generates a key-pair when starting, if one does not already exist.
The entire keypair is in
.Pa local.key ,
and a copy of the public key suitable for transferring to other hosts
is extracted into
.Pa /etc/isakmpd/local.pub .
There has to be a certificate for
.Pa local.key
in the certificate directory,
.Pa /etc/isakmpd/certs/ .
.Pa local.key
has the same mode requirements as
.Pa isakmpd.conf .
.It Pa /etc/isakmpd/pubkeys/
The directory in which trusted public keys are kept.
The keys must be named in the fashion described above.
.It Pa /var/run/isakmpd.fifo
The FIFO used to manually control
.Nm isakmpd .
.It Pa /var/run/isakmpd.pcap
The default IKE packet capture file.
.It Pa /var/run/isakmpd.pid
The PID of the current daemon.
.It Pa /var/run/isakmpd.report
The report file written when
.Dv SIGUSR1
is received.
.It Pa /var/run/isakmpd.result
The report file written when the
.Sq S
or
.Sq "C get"
command is issued in the command FIFO.
.El
.Sh SEE ALSO
.Xr openssl 1 ,
.Xr getnameinfo 3 ,
.Xr pcap_open_offline 3 ,
.Xr ipsec 4 ,
.Xr ipsec.conf 5 ,
.Xr isakmpd.conf 5 ,
.Xr isakmpd.policy 5 ,
.Xr iked 8 ,
.Xr sasyncd 8 ,
.Xr ssl 8 ,
.Xr tcpdump 8
.Sh STANDARDS
.Rs
.%A D. Piper
.%D November 1998
.%R RFC 2407
.%T The Internet IP Security Domain of Interpretation for ISAKMP
.Re
.Pp
.Rs
.%A D. Maughan
.%A M. Schertler
.%A M. Schneider
.%A J. Turner
.%D November 1998
.%R RFC 2408
.%T Internet Security Association and Key Management Protocol (ISAKMP)
.Re
.Pp
.Rs
.%A D. Harkins
.%A D. Carrel
.%D November 1998
.%R RFC 2409
.%T The Internet Key Exchange (IKE)
.Re
.Pp
.Rs
.%A T. Kivinen
.%A B. Swander
.%A A. Huttunen
.%A V. Volpe
.%D January 2005
.%R RFC 3947
.%T Negotiation of NAT-Traversal in the IKE
.Re
.Sh HISTORY
This implementation of the ISAKMP/Oakley key management protocol
was done in 1998 by Niklas Hallqvist and Niels Provos,
sponsored by Ericsson Radio Systems.
.Sh CAVEATS
When storing a trusted public key for an IPv6 identity, the
.Em most efficient
form of address representation, i.e. "::" instead of ":0:0:0:",
must be used or the matching will fail.
.Nm
uses the output from
.Xr 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
.Nm
listens on without a restart.
.Pp
For redundant setups with
.Xr carp 4
and
.Xr sasyncd 8 ,
.Xr sasyncd 8
must be manually restarted every time
.Nm
is restarted, and
.Xr isakmpd.conf 5
must explicitly configure
.Nm
to listen on the virtual IP address of each
.Xr carp 4
interface.