--- name: "isakmpd" section: "8" platform: "openbsd" package: "man" version: "8.0-current-20261101" release: "OpenBSD 8.0-current (2026-11-01)" platforms: ["linux", "openbsd"] url: "https://new.carta.tech/isakmpd" --- # isakmpd(8) ISAKMP/Oakley a.k.a. IKEv1 key management daemon ## NAME **isakmpd** – ISAKMP/Oakley a.k.a. IKEv1 key management daemon ## SYNOPSIS **isakmpd** \[**-46adKLnSTv**\] \[**-c** *config-file*\] \[**-D** *class*=*level*\] \[**-f** *fifo*\] \[**-l** *packetlog-file*\] \[**-N** *udpencap-port*\] \[**-p** *listen-port*\] ## DESCRIPTION The **isakmpd** daemon establishes Security Associations (SAs) for encrypted and/or authenticated network traffic. At this moment, and probably forever, this means [ipsec(4)](/ipsec/4.md) traffic. Traditionally, **isakmpd** was configured using the [isakmpd.conf(5)](/isakmpd.conf/5.md) file format. A newer, much simpler format is now available: [ipsec.conf(5)](/ipsec.conf/5.md). **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 5996, is not supported by **isakmpd** but by [iked(8)](/iked/8.md). 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)](/carp/4.md) and [sasyncd(8)](/sasyncd/8.md). For other uses, some more knowledge of IKEv1 as a protocol is required. The RFCs mentioned below are a possible starting point. On startup **isakmpd** forks into two processes for privilege separation. The unprivileged child jails itself with [chroot(8)](/chroot/8.md) 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. Instead manual flows may be configured using [ipsec.conf(5)](/ipsec.conf/5.md) or by programs such as [bgpd(8)](/bgpd/8.md). Thus **isakmpd** only takes care of 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 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)](/isakmpd.conf/5.md) format, not those in the [ipsec.conf(5)](/ipsec.conf/5.md) format. - **-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 debugging 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. - **-K** When this option is given, **isakmpd** does not read the policy configuration file and no [keynote(4)](/keynote/4.md) policy check is accomplished. This option can be used when policies for flows and SA establishment are arranged by other programs like [ipsecctl(8)](/ipsecctl/8.md) or [bgpd(8)](/bgpd/8.md). - **-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. - **-S** This option is used for setups using [sasyncd(8)](/sasyncd/8.md) and [carp(4)](/carp/4.md) 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 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 information). ## 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* \[**force**\] 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 ‘add’ operation. NOTE: Sending **isakmpd** a SIGHUP or an "R" through the FIFO will void any updates done to the configuration. - **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 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. - **M** **active** - **M** **passive** Set **isakmpd** to active or passive mode. In passive mode no packets are sent to peers. - **p** **on**\[=*path*\] - **R** Reinitialize **isakmpd**, as when sent a SIGHUP signal. - **r** Report **isakmpd** internal state to [syslog(3)](/syslog/3.md). See the **-R** option. Same as when sent a SIGUSR1 signal. - **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)](/isakmpd.conf/5.md) 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)](/openssl/1.md) 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. - Host Keys: Public keys are used to authenticate. See PUBLIC KEY AUTHENTICATION below. - X.509 Certificates: X.509 Certificates are used to authenticate. See X.509 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)](/isakmpd.conf/5.md) 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)](/openssl/1.md)) 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* Depending on the ID-type field of [isakmpd.conf(5)](/isakmpd.conf/5.md), 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)](/isakmpd.conf/5.md). ## X.509 AUTHENTICATION X.509 is a framework for public key certificates. Certificates can be generated using [openssl(1)](/openssl/1.md) 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). First, create a private key for the CA, and a Certificate Signing Request (CSR) to enable the CA to sign its own key: ``` # openssl genrsa -out /etc/ssl/private/ca.key 2048 # openssl req -new -key /etc/ssl/private/ca.key \ -out /etc/ssl/private/ca.csr ``` **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. After the CSR has been generated, it is used to create and sign a certificate for the CA: ``` # openssl x509 -req -days 365 -in /etc/ssl/private/ca.csr \ -signkey /etc/ssl/private/ca.key \ -extfile /etc/ssl/x509v3.cnf -extensions x509v3_CA \ -out /etc/ssl/ca.crt ``` 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. 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. ``` # 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 configuration file is used to add a *subjectAltName* extension field matching the ID used by **isakmpd** to the certificate. If using an IPv4 ID, copy */etc/ssl/x509v3.cnf* to a temporary file and edit it to replace $ENV::CERTIP with the IP address (10.0.0.1 in this example), then generate a signed certificate: ``` # sed 's,\$ENV::CERTIP,10.0.0.1,' \ < /etc/ssl/x509v3.cnf > ~/tmp_x509v3.cnf # openssl x509 -req \ -days 365 -in 10.0.0.1.csr \ -CA /etc/ssl/ca.crt -CAkey /etc/ssl/private/ca.key \ -CAcreateserial -extfile ~/tmp_x509v3.cnf \ -extensions x509v3_IPAddr -out 10.0.0.1.crt ``` For an FQDN certificate, replace $ENV::CERTFQDN with the hostname and generate a signed certificate: ``` # sed 's,\$ENV::CERTFQDN,somehost.somedomain,' \ < /etc/ssl/x509v3.cnf > ~/tmp_x509v3.cnf # openssl x509 -req \ -days 365 -in somehost.somedomain.csr \ -CA /etc/ssl/ca.crt -CAkey /etc/ssl/private/ca.key \ -CAcreateserial -extfile ~/tmp_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)](/ipsec.conf/5.md). A similar setup will be required if [isakmpd.conf(5)](/isakmpd.conf/5.md) is being used instead. 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)](/openssl/1.md) and the ‘crl’ subcommand for more info. ## KEYNOTE AUTHENTICATION Keynote is a trust-management framework. Keys can be generated using [keynote(1)](/keynote/1.md) and provide an alternative means for **isakmpd** to authenticate. See [keynote(4)](/keynote/4.md) 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 information it must not be readable by anyone but the user running **isakmpd**. - */etc/isakmpd/isakmpd.policy* The keynote policy configuration file. The same mode requirements as *isakmpd.conf*. - */etc/isakmpd/keynote/* The directory where KeyNote credentials are kept. - */etc/isakmpd/private/* The directory where local private keys used for public key authentication are kept. By default, the system startup script [rc(8)](/rc/8.md) 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*. - */etc/isakmpd/pubkeys/* The directory in which trusted public keys are kept. The keys must be named in the fashion described above. - */var/run/isakmpd.fifo* The FIFO used to manually control ## SEE ALSO [openssl(1)](/openssl/1.md), [getnameinfo(3)](/getnameinfo/3.md), [ipsec(4)](/ipsec/4.md), [ipsec.conf(5)](/ipsec.conf/5.md), [isakmpd.conf(5)](/isakmpd.conf/5.md), [isakmpd.policy(5)](/isakmpd.policy/5.md), [iked(8)](/iked/8.md), [sasyncd(8)](/sasyncd/8.md), [ssl(8)](/ssl/8.md) ## STANDARDS D. Piper, *The Internet IP Security Domain of Interpretation for ISAKMP*, RFC 2407, November 1998. D. Maughan, M. Schertler, M. Schneider, and J. Turner, *Internet Security Association and Key Management Protocol (ISAKMP)*, RFC 2408, November 1998. D. Harkins and D. Carrel, *The Internet Key Exchange (IKE)*, RFC 2409, November 1998. T. Kivinen, B. Swander, A. Huttunen, and V. Volpe, *Negotiation of NAT-Traversal in the IKE*, RFC 3947, January 2005. ## 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. ## 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)](/getnameinfo/3.md) 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 with [carp(4)](/carp/4.md) and [sasyncd(8)](/sasyncd/8.md), [sasyncd(8)](/sasyncd/8.md) must be manually restarted every time **isakmpd** is restarted, and [isakmpd.conf(5)](/isakmpd.conf/5.md) must explicitly configure **isakmpd** to listen on the virtual IP address of each [carp(4)](/carp/4.md) interface.