ISAKMPD(8) OpenBSD System Manager's Manual ISAKMPD(8)
NAME
isakmpd - ISAKMP/Oakley a.k.a. IKE key management daemon
SYNOPSIS
isakmpd [-46adKLnTv] [-c config-file] [-D class=level] [-f fifo]
[-i pid-file] [-l packetlog-file] [-N udpencap-port]
[-p listen-port] [-R report-file]
DESCRIPTION
The isakmpd daemon establishes security associations for encrypted and/or
authenticated network traffic. At this moment, and probably forever,
this means ipsec(4) traffic.
The way isakmpd goes about its work is by maintaining an internal config-
uration as well as a policy database which describes what kinds of SAs to
negotiate, and by listening for different events that trigger these nego-
tiations. The events that control isakmpd consist of negotiation initia-
tions 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 trig-
gered by timers running out.
Most uses of isakmpd will be to implement so called "virtual private net-
works" (VPNs). The vpn(8) manual page describes how to set up isakmpd
for a simple VPN. For other uses, some more knowledge of IKE as a proto-
col is required. One source of information are the RFCs mentioned below.
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
IPv6.
-a If given, isakmpd does not set up flows automatically. This is
useful when flows are configured with ipsecadm(8) or by other
programs like bgpd(8). Thus isakmpd only takes care of the SA
establishment.
-c config-file
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 run-
ning the daemon. isakmpd will reread the configuration file when
sent a SIGHUP signal.
-D class=level
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 de-
bugging classes are set to the specified level.
Valid values for class are as follows:
0 Misc
1 Transport
2 Message
3 Crypto
4 Timer
5 Sysdep
6 SA
7 Exchange
8 Negotiation
9 Policy
10 FIFO user interface
A All
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.
-f fifo
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.
-i pid-file
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 con-
figuration file and no keynote(4) policy check is accomplished.
This option can be used when policies for flows and SA establish-
ment are arranged by other programs like ipsecadm(8) or bgpd(8).
-L Enable IKE packet capture. When this option is given, isakmpd
will capture to file an unencrypted copy of the negotiation pack-
ets it is sending and receiving. This file can later be read by
tcpdump(8) and other utilities using pcap(3).
-l packetlog-file
As option -L above, but capture to a specified file.
-N udpencap-port
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.
-p listen-port
The -p option specifies the listen port the daemon will bind to.
-R report-file
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
allowed.
-T When this option is given, NAT-Traversal will be disabled and
isakmpd will not advertise support for NAT-Traversal to its
peers.
-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 in-
formation).
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 com-
mand-specific options. Available commands are:
C add [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 con-
figuration list tag. `rm' removes a tag in a section. `rms' re-
moves an entire section.
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.
c <name>
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 speci-
fied 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.
p on[=<path>]
p off Enable or disable cleartext IKE packet capture. When enabling,
optionally specify which file isakmpd should capture the packets
to.
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
/var/run/isakmpd.result file.
T Tear down all active connections.
t <name>
Tear down the named connection, if active.
SETTING UP AN IKE PUBLIC KEY INFRASTRUCTURE (PKI)
In order to use public key based authentication, there has to be an in-
frastructure managing the key signing. Either there is an already exist-
ing 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:
Passphrase:
This method does not use keys at all, but relies on a shared
passphrase. See vpn(8) for an example implementation.
Host Keys:
Public keys are used to authenticate. See PUBLIC KEY
AUTHENTICATION below.
X509 Certificates:
X509 Certificates are used to authenticate. See X509
AUTHENTICATION below.
Keynote Certificates:
Keynote Certificates are used to authenticate. See KEYNOTE
AUTHENTICATION below.
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
formula:
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: /etc/isakmpd/pubkeys/ufqdn/user@foo.bar.org
By default, the system startup script rc(8) generates a key-pair when
starting, if one does not already exist. The private and public keys are
named local.key and local.pub, respectively. 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_AD-
DR_SUBNET), fully qualified domain name (FDQN), user fully qualified do-
main name (USER_FQDN), or key ID (KEY_ID).
For example, isakmpd can authenticate using the pre-generated keys if the
local public key is copied to the remote gateway as
/etc/isakmpd/pubkeys/ipv4/local.gateway.ip.address and the remote gate-
way'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).
X509 AUTHENTICATION
X509 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:1024 \
-keyout /etc/ssl/private/ca.key \
-out /etc/ssl/ca.crt
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. By default, the system
startup script rc(8) generates a key-pair when starting, if one does
not already exist. The private and public keys are named local.key
and local.pub, respectively.
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 \
-out /etc/isakmpd/private/10.0.0.1.csr
Now take these certificate signing requests to your CA and process
them as below. A subjectAltName extension field should be added to
the certificate. This field is not mandatory, but is highly recom-
mended since it allows isakmpd to avoid ``man in the middle'' at-
tacks. Replace 10.0.0.1 with the IP address which isakmpd will use
as the certificate identity.
# setenv 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:
# setenv 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
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 AUTHENTICATION
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.
FILES
/etc/isakmpd/ca/
The directory where CA certificates are kept.
/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.
/etc/isakmpd/crls/
The directory where CRLs are kept.
/etc/isakmpd/isakmpd.conf
The configuration file. As this file can contain sensitive in-
formation it must not be readable by anyone but the user running
isakmpd.
/etc/isakmpd/isakmpd.policy
The keynote policy configuration file. The same mode require-
ments as isakmpd.conf.
/etc/isakmpd/keynote/
The directory where KeyNote credentials are kept.
/etc/isakmpd/private/
The directory where local private keys for certificate-based au-
thentication, and their public key counterparts, are kept. By
default, the system startup script rc(8) generates a key-pair
when starting, if one does not already exist. The private and
public keys are named local.key and local.pub, respectively.
There has to be a certificate for local.key in the certificate
directory, /etc/isakmpd/certs/. local.key has the same mode re-
quirements as isakmpd.conf.
/etc/isakmpd/pubkeys/
The directory in which trusted public keys are kept. The keys
must be named in the fashion described above.
/usr/share/ipsec/isakmpd/
A directory containing some sample isakmpd and keynote policy
configuration files.
/var/run/isakmpd.fifo
The FIFO used to manually control isakmpd.
/var/run/isakmpd.pcap
The default IKE packet capture file.
/var/run/isakmpd.pid
The PID of the current daemon.
/var/run/isakmpd.report
The report file written when SIGUSR1 is received.
/var/run/isakmpd.result
The report file written when the `S' or `C get' command is issued
in the command FIFO.
SEE ALSO
openssl(1), getnameinfo(3), pcap(3), ipsec(4), isakmpd.conf(5),
isakmpd.policy(5), ssl(8), tcpdump(8), vpn(8)
HISTORY
The ISAKMP/Oakley key management protocol is described in RFC 2407, RFC
2408, and RFC 2409. NAT-Traversal is described in RFC 3947. This imple-
mentation was done 1998 by Niklas Hallqvist and Niels Provos, sponsored
by Ericsson Radio Systems.
CAVEATS
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 pro-
cess 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.
OpenBSD 3.8 August 07, 2002 7