STRONGSWAN.CONF(5) strongSwan STRONGSWAN.CONF(5)NAME
strongswan.conf - strongSwan configuration file
DESCRIPTION
While the ipsec.conf(5) configuration file is well suited to define
IPsec related configuration parameters, it is not useful for other
strongSwan applications to read options from this file. The file is
hard to parse and only ipsec starter is capable of doing so. As the
number of components of the strongSwan project is continually growing,
a more flexible configuration file was needed, one that is easy to
extend and can be used by all components. With strongSwan 4.2.1
strongswan.conf(5) was introduced which meets these requirements.
SYNTAX
The format of the strongswan.conf file consists of hierarchical sec‐
tions and a list of key/value pairs in each section. Each section has a
name, followed by C-Style curly brackets defining the section body.
Each section body contains a set of subsections and key/value pairs:
settings := (section|keyvalue)*
section := name { settings }
keyvalue := key = value\n
Values must be terminated by a newline.
Comments are possible using the #-character, but be careful: The parser
implementation is currently limited and does not like brackets in com‐
ments.
Section names and keys may contain any printable character except:
. { } # \n \t space
An example file in this format might look like this:
a = b
section-one {
somevalue = asdf
subsection {
othervalue = xxx
}
# yei, a comment
yetanother = zz
}
section-two {
x = 12
}
Indentation is optional, you may use tabs or spaces.
INCLUDING FILES
Using the include statement it is possible to include other files into
strongswan.conf, e.g.
include /some/path/*.conf
If the file name is not an absolute path, it is considered to be rela‐
tive to the directory of the file containing the include statement. The
file name may include shell wildcards (see sh(1)). Also, such inclu‐
sions can be nested.
Sections loaded from included files extend previously loaded sections;
already existing values are replaced. It is important to note that
settings are added relative to the section the include statement is in.
As an example, the following three files result in the same final con‐
fig as the one given above:
a = b
section-one {
somevalue = before include
include include.conf
}
include other.conf
include.conf:
# settings loaded from this file are added to section-one
# the following replaces the previous value
somevalue = asdf
subsection {
othervalue = yyy
}
yetanother = zz
other.conf:
# this extends section-one and subsection
section-one {
subsection {
# this replaces the previous value
othervalue = xxx
}
}
section-two {
x = 12
}
READING VALUES
Values are accessed using a dot-separated section list and a key. With
reference to the example above, accessing section-one.subsection.other‐
value will return xxx.
DEFINED KEYS
The following keys are currently defined (using dot notation). The
default value (if any) is listed in brackets after the key.
attest section
attest.database
Path to database with file measurement information
attest.load
Plugins to load in ipsec attest tool
charon section
Note: Many of these options also apply to charon-cmd and other charon
derivatives. Just use their respective name (e.g. charon-cmd)
instead of charon.
charon.block_threshold [5]
Maximum number of half-open IKE_SAs for a single peer IP
charon.cisco_unity [no]
Send Cisco Unity vendor ID payload (IKEv1 only)
charon.close_ike_on_child_failure [no]
Close the IKE_SA if setup of the CHILD_SA along with IKE_AUTH
failed
charon.cookie_threshold [10]
Number of half-open IKE_SAs that activate the cookie mechanism
charon.dns1
charon.dns2
DNS servers assigned to peer via configuration payload (CP)
charon.dos_protection [yes]
Enable Denial of Service protection using cookies and aggres‐
siveness checks
charon.filelog
Section to define file loggers, see LOGGER CONFIGURATION
charon.flush_auth_cfg [no]
If enabled objects used during authentication (certificates,
identities etc.) are released to free memory once an IKE_SA is
established. Enabling this might conflict with plugins that
later need access to e.g. the used certificates.
charon.fragment_size [512]
Maximum size (in bytes) of a sent fragment when using the pro‐
prietary IKEv1 fragmentation extension.
charon.group
Name of the group the daemon changes to after startup
charon.half_open_timeout [30]
Timeout in seconds for connecting IKE_SAs (also see IKE_SA_INIT
DROPPING).
charon.hash_and_url [no]
Enable hash and URL support
charon.i_dont_care_about_security_and_use_aggressive_mode_psk [no]
If enabled responders are allowed to use IKEv1 Aggressive Mode
with pre-shared keys, which is discouraged due to security con‐
cerns (offline attacks on the openly transmitted hash of the
PSK)
charon.ignore_routing_tables
A space-separated list of routing tables to be excluded from
route lookups
charon.ikesa_limit [0]
Maximum number of IKE_SAs that can be established at the same
time before new connection attempts are blocked
charon.ikesa_table_segments [1]
Number of exclusively locked segments in the hash table
charon.ikesa_table_size [1]
Size of the IKE_SA hash table
charon.inactivity_close_ike [no]
Whether to close IKE_SA if the only CHILD_SA closed due to inac‐
tivity
charon.init_limit_half_open [0]
Limit new connections based on the current number of half open
IKE_SAs (see IKE_SA_INIT DROPPING).
charon.init_limit_job_load [0]
Limit new connections based on the number of jobs currently
queued for processing (see IKE_SA_INIT DROPPING).
charon.initiator_only [no]
Causes charon daemon to ignore IKE initiation requests.
charon.install_routes [yes]
Install routes into a separate routing table for established
IPsec tunnels
charon.install_virtual_ip [yes]
Install virtual IP addresses
charon.install_virtual_ip_on
The name of the interface on which virtual IP addresses should
be installed. If not specified the addresses will be installed
on the outbound interface.
charon.interfaces_ignore
A comma-separated list of network interfaces that should be
ignored, if charon.interfaces_use is specified this option has
no effect.
charon.interfaces_use
A comma-separated list of network interfaces that should be used
by charon. All other interfaces are ignored.
charon.keep_alive [20s]
NAT keep alive interval
charon.load
Plugins to load in the IKEv2 daemon charon
charon.max_packet [10000]
Maximum packet size accepted by charon
charon.multiple_authentication [yes]
Enable multiple authentication exchanges (RFC 4739)
charon.nbns1
charon.nbns2
WINS servers assigned to peer via configuration payload (CP)
charon.port [500]
UDP port used locally. If set to 0 a random port will be allo‐
cated.
charon.port_nat_t [4500]
UDP port used locally in case of NAT-T. If set to 0 a random
port will be allocated. Has to be different from charon.port,
otherwise a random port will be allocated.
charon.process_route [yes]
Process RTM_NEWROUTE and RTM_DELROUTE events
charon.receive_delay [0]
Delay in ms for receiving packets, to simulate larger RTT
charon.receive_delay_response [yes]
Delay response messages
charon.receive_delay_request [yes]
Delay request messages
charon.receive_delay_type [0]
Specific IKEv2 message type to delay, 0 for any
charon.replay_window [32]
Size of the AH/ESP replay window, in packets.
charon.retransmit_base [1.8]
Base to use for calculating exponential back off, see IKEv2
RETRANSMISSION
charon.retransmit_timeout [4.0]
Timeout in seconds before sending first retransmit
charon.retransmit_tries [5]
Number of times to retransmit a packet before giving up
charon.retry_initiate_interval [0]
Interval to use when retrying to initiate an IKE_SA (e.g. if DNS
resolution failed), 0 to disable retries.
charon.reuse_ikesa [yes]
Initiate CHILD_SA within existing IKE_SAs
charon.routing_table
Numerical routing table to install routes to
charon.routing_table_prio
Priority of the routing table
charon.send_delay [0]
Delay in ms for sending packets, to simulate larger RTT
charon.send_delay_response [yes]
Delay response messages
charon.send_delay_request [yes]
Delay request messages
charon.send_delay_type [0]
Specific IKEv2 message type to delay, 0 for any
charon.send_vendor_id [no]
Send strongSwan vendor ID payload
charon.syslog
Section to define syslog loggers, see LOGGER CONFIGURATION
charon.threads [16]
Number of worker threads in charon
charon.user
Name of the user the daemon changes to after startup
charon.plugins subsection
charon.plugins.android_log.loglevel [1]
Loglevel for logging to Android specific logger
charon.plugins.attr
Section to specify arbitrary attributes that are assigned to a
peer via configuration payload (CP)
charon.plugins.certexpire.csv.cron
Cron style string specifying CSV export times
charon.plugins.certexpire.csv.empty_string
String to use in empty intermediate CA fields
charon.plugins.certexpire.csv.fixed_fields [yes]
Use a fixed intermediate CA field count
charon.plugins.certexpire.csv.force [yes]
Force export of all trustchains we have a private key for
charon.plugins.certexpire.csv.format [%d:%m:%Y]
strftime(3) format string to export expiration dates as
charon.plugins.certexpire.csv.local
strftime(3) format string for the CSV file name to export local
certificates to
charon.plugins.certexpire.csv.remote
strftime(3) format string for the CSV file name to export remote
certificates to
charon.plugins.certexpire.csv.separator [,]
CSV field separator
charon.plugins.coupling.file
File to store coupling list to
charon.plugins.coupling.hash [sha1]
Hashing algorithm to fingerprint coupled certificates
charon.plugins.coupling.max [1]
Maximum number of coupling entries to create
charon.plugins.dhcp.force_server_address [no]
Always use the configured server address. This might be helpful
if the DHCP server runs on the same host as strongSwan, and the
DHCP daemon does not listen on the loopback interface. In that
case the server cannot be reached via unicast (or even
255.255.255.255) as that would be routed via loopback. Setting
this option to yes and configuring the local broadcast address
(e.g. 192.168.0.255) as server address might work.
charon.plugins.dhcp.identity_lease [no]
Derive user-defined MAC address from hash of IKEv2 identity
charon.plugins.dhcp.server [255.255.255.255]
DHCP server unicast or broadcast IP address
charon.plugins.duplicheck.enable [yes]
Enable duplicheck plugin (if loaded)
charon.plugins.duplicheck.socket [unix://${piddir}/charon.dck]
Socket provided by the duplicheck plugin
charon.plugins.eap-aka.request_identity [yes]
charon.plugins.eap-aka-3ggp2.seq_check
charon.plugins.eap-dynamic.preferred
The preferred EAP method(s) to be used. If it is not given the
first registered method will be used initially. If a comma sep‐
arated list is given the methods are tried in the given order
before trying the rest of the registered methods.
charon.plugins.eap-dynamic.prefer_user [no]
If enabled the EAP methods proposed in an EAP-Nak message sent
by the peer are preferred over the methods registered locally.
charon.plugins.eap-gtc.backend [pam]
XAuth backend to be used for credential verification
charon.plugins.eap-peap.fragment_size [1024]
Maximum size of an EAP-PEAP packet
charon.plugins.eap-peap.max_message_count [32]
Maximum number of processed EAP-PEAP packets (0 = no limit)
charon.plugins.eap-peap.include_length [no]
Include length in non-fragmented EAP-PEAP packets
charon.plugins.eap-peap.phase2_method [mschapv2]
Phase2 EAP client authentication method
charon.plugins.eap-peap.phase2_piggyback [no]
Phase2 EAP Identity request piggybacked by server onto TLS Fin‐
ished message
charon.plugins.eap-peap.phase2_tnc [no]
Start phase2 EAP TNC protocol after successful client authenti‐
cation
charon.plugins.eap-peap.request_peer_auth [no]
Request peer authentication based on a client certificate
charon.plugins.eap-radius.accounting [no]
Send RADIUS accounting information to RADIUS servers.
charon.plugins.eap-radius.accounting_requires_vip [no]
If enabled, accounting is disabled unless an IKE_SA has at least
one virtual IP
charon.plugins.eap-radius.class_group [no]
Use the class attribute sent in the RADIUS-Accept message as
group membership information that is compared to the groups
specified in the rightgroups option in ipsec.conf (5).
charon.plugins.eap-radius.close_all_on_timeout [no]
Closes all IKE_SAs if communication with the RADIUS server times
out. If it is not set only the current IKE_SA is closed.
charon.plugins.eap-radius.dae.enable [no]
Enables support for the Dynamic Authorization Extension (RFC
5176)
charon.plugins.eap-radius.dae.listen [0.0.0.0]
Address to listen for DAE messages from the RADIUS server
charon.plugins.eap-radius.dae.port [3799]
Port to listen for DAE requests
charon.plugins.eap-radius.dae.secret
Shared secret used to verify/sign DAE messages
charon.plugins.eap-radius.eap_start [no]
Send EAP-Start instead of EAP-Identity to start RADIUS conversa‐
tion
charon.plugins.eap-radius.filter_id [no]
If the RADIUS tunnel_type attribute with value ESP is received,
use the filter_id attribute sent in the RADIUS-Accept message as
group membership information that is compared to the groups
specified in the rightgroups option in ipsec.conf (5).
charon.plugins.eap-radius.forward.ike_to_radius
RADIUS attributes to be forwarded from IKEv2 to RADIUS (can be
defined by name or attribute number, a colon can be used to
specify vendor-specific attributes, e.g. Reply-Message, or 11,
or 36906:12).
charon.plugins.eap-radius.forward.radius_to_ike
Same as charon.plugins.eap-radius.forward.ike_to_radius but from
RADIUS to IKEv2, a strongSwan specific private notify (40969) is
used to transmit the attributes.
charon.plugins.eap-radius.id_prefix
Prefix to EAP-Identity, some AAA servers use a IMSI prefix to
select the EAP method
charon.plugins.eap-radius.nas_identifier [strongSwan]
NAS-Identifier to include in RADIUS messages
charon.plugins.eap-radius.port [1812]
Port of RADIUS server (authentication)
charon.plugins.eap-radius.secret
Shared secret between RADIUS and NAS
charon.plugins.eap-radius.server
IP/Hostname of RADIUS server
charon.plugins.eap-radius.servers
Section to specify multiple RADIUS servers. The nas_identifier,
secret, sockets and port (or auth_port) options can be specified
for each server. A server's IP/Hostname can be configured using
the address option. The acct_port [1813] option can be used to
specify the port used for RADIUS accounting. For each RADIUS
server a priority can be specified using the preference [0]
option.
charon.plugins.eap-radius.sockets [1]
Number of sockets (ports) to use, increase for high load
charon.plugins.eap-sim.request_identity [yes]
charon.plugins.eap-simaka-sql.database
charon.plugins.eap-simaka-sql.remove_used [no]
charon.plugins.eap-tls.fragment_size [1024]
Maximum size of an EAP-TLS packet
charon.plugins.eap-tls.max_message_count [32]
Maximum number of processed EAP-TLS packets (0 = no limit)
charon.plugins.eap-tls.include_length [yes]
Include length in non-fragmented EAP-TLS packets
charon.plugins.eap-tnc.max_message_count [10]
Maximum number of processed EAP-TNC packets (0 = no limit)
charon.plugins.eap-tnc.protocol [tnccs-1.1]
IF-TNCCS protocol version to be used (tnccs-1.1, tnccs-2.0,
tnccs-dynamic)
charon.plugins.eap-ttls.fragment_size [1024]
Maximum size of an EAP-TTLS packet
charon.plugins.eap-ttls.max_message_count [32]
Maximum number of processed EAP-TTLS packets (0 = no limit)
charon.plugins.eap-ttls.include_length [yes]
Include length in non-fragmented EAP-TTLS packets
charon.plugins.eap-ttls.phase2_method [md5]
Phase2 EAP client authentication method
charon.plugins.eap-ttls.phase2_piggyback [no]
Phase2 EAP Identity request piggybacked by server onto TLS Fin‐
ished message
charon.plugins.eap-ttls.phase2_tnc [no]
Start phase2 EAP TNC protocol after successful client authenti‐
cation
charon.plugins.eap-ttls.request_peer_auth [no]
Request peer authentication based on a client certificate
charon.plugins.error-notify.socket [unix://${piddir}/charon.enfy]
Socket provided by the error-notify plugin
charon.plugins.ha.autobalance [0]
Interval in seconds to automatically balance handled segments
between nodes. Set to 0 to disable.
charon.plugins.ha.fifo_interface [yes]
charon.plugins.ha.heartbeat_delay [1000]
charon.plugins.ha.heartbeat_timeout [2100]
charon.plugins.ha.local
charon.plugins.ha.monitor [yes]
charon.plugins.ha.pools
charon.plugins.ha.remote
charon.plugins.ha.resync [yes]
charon.plugins.ha.secret
charon.plugins.ha.segment_count [1]
charon.plugins.ipseckey.enable [no]
Enable the fetching of IPSECKEY RRs via DNS
charon.plugins.led.activity_led
charon.plugins.led.blink_time [50]
charon.plugins.kernel-klips.ipsec_dev_count [4]
Number of ipsecN devices
charon.plugins.kernel-klips.ipsec_dev_mtu [0]
Set MTU of ipsecN device
charon.plugins.kernel-netlink.roam_events [yes]
Whether to trigger roam events when interfaces, addresses or
routes change
charon.plugins.kernel-pfroute.vip_wait [1000]
Time in ms to wait until virtual IP addresses appear/disappear
before failing.
charon.plugins.load-tester
Section to configure the load-tester plugin, see LOAD TESTS
charon.plugins.lookip.socket [unix://${piddir}/charon.lkp]
Socket provided by the lookip plugin
charon.plugins.radattr.dir
Directory where RADIUS attributes are stored in client-ID spe‐
cific files.
charon.plugins.radattr.message_id [-1]
Attributes are added to all IKE_AUTH messages by default (-1),
or only to the IKE_AUTH message with the given IKEv2 message ID.
charon.plugins.resolve.file [/etc/resolv.conf]
File where to add DNS server entries
charon.plugins.resolve.resolvconf.iface_prefix [lo.inet.ipsec.]
Prefix used for interface names sent to resolvconf(8). The name‐
server address is appended to this prefix to make it unique.
The result has to be a valid interface name according to the
rules defined by resolvconf. Also, it should have a high prior‐
ity according to the order defined in interface-order(5).
charon.plugins.socket-default.set_source [yes]
Set source address on outbound packets, if possible.
charon.plugins.socket-default.use_ipv4 [yes]
Listen on IPv4, if possible.
charon.plugins.socket-default.use_ipv6 [yes]
Listen on IPv6, if possible.
charon.plugins.sql.database
Database URI for charons SQL plugin
charon.plugins.sql.loglevel [-1]
Loglevel for logging to SQL database
charon.plugins.stroke.ignore_missing_ca_basic_constraint [no]
Treat certificates in ipsec.d/cacerts and ipsec.conf ca sections
as CA certificates even if they don't contain a CA basic con‐
straint.
charon.plugins.stroke.max_concurrent [4]
Maximum number of stroke messages handled concurrently
charon.plugins.stroke.socket [unix://${piddir}/charon.ctl]
Socket provided by the stroke plugin
charon.plugins.stroke.timeout [0]
Timeout in ms for any stroke command. Use 0 to disable the time‐
out
charon.plugins.systime-fix.interval [0]
Interval in seconds to check system time for validity. 0 dis‐
ables the check
charon.plugins.systime-fix.reauth [no]
Whether to use reauth or delete if an invalid cert lifetime is
detected
charon.plugins.systime-fix.threshold
Threshold date where system time is considered valid. Disabled
if not specified
charon.plugins.systime-fix.threshold_format [%Y]
strptime(3) format used to parse threshold option
charon.plugins.tnccs-11.max_message_size [45000]
Maximum size of a PA-TNC message (XML & Base64 encoding)
charon.plugins.tnccs-20.max_batch_size [65522]
Maximum size of a PB-TNC batch (upper limit via PT-EAP = 65529)
charon.plugins.tnccs-20.max_message_size [65490]
Maximum size of a PA-TNC message (upper limit via PT-EAP =
65497)
charon.plugins.tnc-ifmap.client_cert
Path to X.509 certificate file of IF-MAP client
charon.plugins.tnc-ifmap.client_key
Path to private key file of IF-MAP client
charon.plugins.tnc-ifmap.device_name
Unique name of strongSwan server as a PEP and/or PDP device
charon.plugins.tnc-ifmap.renew_session_interval [150]
Interval in seconds between periodic IF-MAP RenewSession
requests
charon.plugins.tnc-ifmap.server_uri [https://localhost:8444/imap]
URI of the form [https://]servername[:port][/path]
charon.plugins.tnc-ifmap.server_cert
Path to X.509 certificate file of IF-MAP server
charon.plugins.tnc-ifmap.username_password
Credentials of IF-MAP client of the form username:password
charon.plugins.tnc-imc.dlclose [yes]
Unload IMC after use
charon.plugins.tnc-imc.preferred_language [en]
Preferred language for TNC recommendations
charon.plugins.tnc-imv.dlclose [yes]
Unload IMV after use
charon.plugins.tnc-pdp.method [ttls]
EAP tunnel method to be used
charon.plugins.tnc-pdp.port [1812]
RADIUS server port the strongSwan PDP is listening on
charon.plugins.tnc-pdp.secret
Shared RADIUS secret between strongSwan PDP and NAS
charon.plugins.tnc-pdp.server
Name of the strongSwan PDP as contained in the AAA certificate
charon.plugins.tnc-pdp.timeout
Timeout in seconds before closing incomplete connections
charon.plugins.updown.dns_handler [no]
Whether the updown script should handle DNS serves assigned via
IKEv1 Mode Config or IKEv2 Config Payloads (if enabled they
can't be handled by other plugins, like resolve)
charon.plugins.whitelist.enable [yes]
Enable loaded whitelist plugin
charon.plugins.whitelist.socket [unix://${piddir}/charon.wlst]
Socket provided by the whitelist plugin
charon.plugins.xauth-eap.backend [radius]
EAP plugin to be used as backend for XAuth credential verifica‐
tion
charon.plugins.xauth-pam.pam_service [login]
PAM service to be used for authentication
libstrongswan section
libstrongswan.cert_cache [yes]
Whether relations in validated certificate chains should be
cached in memory
libstrongswan.crypto_test.bench [no]
libstrongswan.crypto_test.bench_size [1024]
libstrongswan.crypto_test.bench_time [50]
libstrongswan.crypto_test.on_add [no]
Test crypto algorithms during registration
libstrongswan.crypto_test.on_create [no]
Test crypto algorithms on each crypto primitive instantiation
libstrongswan.crypto_test.required [no]
Strictly require at least one test vector to enable an algorithm
libstrongswan.crypto_test.rng_true [no]
Whether to test RNG with TRUE quality; requires a lot of entropy
libstrongswan.dh_exponent_ansi_x9_42 [yes]
Use ANSI X9.42 DH exponent size or optimum size matched to cryp‐
tographical strength
libstrongswan.ecp_x_coordinate_only [yes]
Compliance with the errata for RFC 4753
libstrongswan.host_resolver.max_threads [3]
Maximum number of concurrent resolver threads (they are termi‐
nated if unused)
libstrongswan.host_resolver.min_threads [0]
Minimum number of resolver threads to keep around
libstrongswan.integrity_test [no]
Check daemon, libstrongswan and plugin integrity at startup
libstrongswan.leak_detective.detailed [yes]
Includes source file names and line numbers in leak detective
output
libstrongswan.leak_detective.usage_threshold [10240]
Threshold in bytes for leaks to be reported (0 to report all)
libstrongswan.leak_detective.usage_threshold_count [0]
Threshold in number of allocations for leaks to be reported (0
to report all)
libstrongswan.processor.priority_threads
Subsection to configure the number of reserved threads per pri‐
ority class see JOB PRIORITY MANAGEMENT
libstrongswan.x509.enforce_critical [yes]
Discard certificates with unsupported or unknown critical exten‐
sions
libstrongswan.plugins subsection
libstrongswan.plugins.attr-sql.database
Database URI for attr-sql plugin used by charon
libstrongswan.plugins.attr-sql.lease_history [yes]
Enable logging of SQL IP pool leases
libstrongswan.plugins.gcrypt.quick_random [no]
Use faster random numbers in gcrypt; for testing only, produces
weak keys!
libstrongswan.plugins.openssl.engine_id [pkcs11]
ENGINE ID to use in the OpenSSL plugin
libstrongswan.plugins.openssl.fips_mode [0]
Set OpenSSL FIPS mode: disabled(0), enabled(1), Suite B
enabled(2)
libstrongswan.plugins.pkcs11.modules
List of available PKCS#11 modules
libstrongswan.plugins.pkcs11.load_certs [yes]
Whether to load certificates from tokens
libstrongswan.plugins.pkcs11.reload_certs [no]
Reload certificates from all tokens if charon receives a SIGHUP
libstrongswan.plugins.pkcs11.use_dh [no]
Whether the PKCS#11 modules should be used for DH and ECDH (see
use_ecc option)
libstrongswan.plugins.pkcs11.use_ecc [no]
Whether the PKCS#11 modules should be used for ECDH and ECDSA
public key operations. ECDSA private keys can be used regardless
of this option
libstrongswan.plugins.pkcs11.use_hasher [no]
Whether the PKCS#11 modules should be used to hash data
libstrongswan.plugins.pkcs11.use_pubkey [no]
Whether the PKCS#11 modules should be used for public key opera‐
tions, even for keys not stored on tokens
libstrongswan.plugins.pkcs11.use_rng [no]
Whether the PKCS#11 modules should be used as RNG
libstrongswan.plugins.random.random [/dev/random]
File to read random bytes from, instead of /dev/random
libstrongswan.plugins.random.urandom [/dev/urandom]
File to read pseudo random bytes from, instead of /dev/urandom
libstrongswan.plugins.unbound.resolv_conf [/etc/resolv.conf]
File to read DNS resolver configuration from
libstrongswan.plugins.unbound.trust_anchors [/etc/ipsec.d/dnssec.keys]
File to read DNSSEC trust anchors from (usually root zone KSK)
libtls section
libtls.cipher
List of TLS encryption ciphers
libtls.key_exchange
List of TLS key exchange methods
libtls.mac
List of TLS MAC algorithms
libtls.suites
List of TLS cipher suites
libtnccs section
libtnccs.tnc_config [/etc/tnc_config]
TNC IMC/IMV configuration directory
libimcv section
libimcv.assessment_result [yes]
Whether IMVs send a standard IETF Assessment Result attribute
libimcv.database
Global IMV policy database URI
libimcv.debug_level [1]
Debug level for a stand-alone libimcv library
libimcv.load [random nonce gmp pubkey x509]
Plugins to load in IMC/IMVs
libimcv.os_info.name
Manually set the name of the client OS (e.g. Ubuntu)
libimcv.os_info.version
Manually set the version of the client OS (e.g. 12.04 i686)
libimcv.policy_script [ipsec _imv_policy]
Script called for each TNC connection to generate IMV policies
libimcv.stderr_quiet [no]
isable output to stderr with a stand-alone libimcv library
libimcv plugins section
libimcv.plugins.imc-attestation.aik_blob
AIK encrypted private key blob file
libimcv.plugins.imc-attestation.aik_cert
AIK certificate file
libimcv.plugins.imc-attestation.aik_key
AIK public key file
libimcv.plugins.imv-attestation.nonce_len [20]
DH nonce length
libimcv.plugins.imv-attestation.use_quote2 [yes]
Use Quote2 AIK signature instead of Quote signature
libimcv.plugins.imv-attestation.cadir
Path to directory with AIK cacerts
libimcv.plugins.imv-attestation.dh_group [ecp256]
Preferred Diffie-Hellman group
libimcv.plugins.imv-attestation.hash_algorithm [sha256]
Preferred measurement hash algorithm
libimcv.plugins.imv-attestation.min_nonce_len [0]
DH minimum nonce length
libimcv.plugins.imv-attestation.remediation_uri
URI pointing to attestation remediation instructions
libimcv.plugins.imc-os.push_info [yes]
Send operating system info without being prompted
libimcv.plugins.imv-os.remediation_uri
URI pointing to operating system remediation instructions
libimcv.plugins.imc-scanner.push_info [yes]
Send open listening ports without being prompted
libimcv.plugins.imv-scanner.remediation_uri
URI pointing to scanner remediation instructions
libimcv.plugins.imc-test.additional_ids [0]
Number of additional IMC IDs
libimcv.plugins.imc-test.command [none]
Command to be sent to the Test IMV
libimcv.plugins.imc-test.dummy_size [0]
Size of dummy attribute to be sent to the Test IMV (0 = dis‐
abled)
libimcv.plugins.imv-test.remediation_uri
URI pointing to test remediation instructions
libimcv.plugins.imc-test.retry [no]
Do a handshake retry
libimcv.plugins.imc-test.retry_command
Command to be sent to the Test IMV in the handshake retry
libimcv.plugins.imv-test.rounds [0]
Number of IMC-IMV retry rounds
manager section
manager.database
Credential database URI for manager
manager.debug [no]
Enable debugging in manager
manager.load
Plugins to load in manager
manager.socket
FastCGI socket of manager, to run it statically
manager.threads [10]
Threads to use for request handling
manager.timeout [15m]
Session timeout for manager
mediation client section
medcli.database
Mediation client database URI
medcli.dpd [5m]
DPD timeout to use in mediation client plugin
medcli.rekey [20m]
Rekeying time on mediation connections in mediation client plug‐
in
mediation server section
medsrv.database
Mediation server database URI
medsrv.debug [no]
Debugging in mediation server web application
medsrv.dpd [5m]
DPD timeout to use in mediation server plugin
medsrv.load
Plugins to load in mediation server plugin
medsrv.password_length [6]
Minimum password length required for mediation server user
accounts
medsrv.rekey [20m]
Rekeying time on mediation connections in mediation server plug‐
in
medsrv.socket
Run Mediation server web application statically on socket
medsrv.threads [5]
Number of thread for mediation service web application
medsrv.timeout [15m]
Session timeout for mediation service
openac section
openac.load
Plugins to load in ipsec openac tool
pacman section
pacman.database
Database URI for the database that stores the package informa‐
tion
pki section
pki.load
Plugins to load in ipsec pki tool
pool section
pool.load
Plugins to load in ipsec pool tool
scepclient section
scepclient.load
Plugins to load in ipsec scepclient tool
starter section
starter.load
Plugins to load in starter
starter.load_warning [yes]
Disable charon plugin load option warning
LOGGER CONFIGURATION
The options described below provide a much more flexible way to config‐
ure loggers for the IKEv2 daemon charon than using the charondebug
option in ipsec.conf(5).
Please note that if any loggers are specified in strongswan.conf,
charondebug does not have any effect.
There are currently two types of loggers defined:
File loggers
Log directly to a file and are defined by specifying the full
path to the file as subsection in the charon.filelog section. To
log to the console the two special filenames stdout and stderr
can be used.
Syslog loggers
Log into a syslog facility and are defined by specifying the
facility to log to as the name of a subsection in the
charon.syslog section. The following facilities are currently
supported: daemon and auth.
Multiple loggers can be defined for each type with different log ver‐
bosity for the different subsystems of the daemon.
Options
charon.filelog.<filename>.default [1]
charon.syslog.<facility>.default
Specifies the default loglevel to be used for subsystems for
which no specific loglevel is defined.
charon.filelog.<filename>.<subsystem> [<default>]
charon.syslog.<facility>.<subsystem>
Specifies the loglevel for the given subsystem.
charon.filelog.<filename>.append [yes]
If this option is enabled log entries are appended to the exist‐
ing file.
charon.filelog.<filename>.flush_line [no]
Enabling this option disables block buffering and enables line
buffering.
charon.filelog.<filename>.ike_name [no]
charon.syslog.<facility>.ike_name
Prefix each log entry with the connection name and a unique
numerical identifier for each IKE_SA.
charon.filelog.<filename>.time_format
Prefix each log entry with a timestamp. The option accepts a
format string as passed to strftime(3).
charon.syslog.identifier
Global identifier used for an openlog(3) call, prepended to each
log message by syslog. If not configured, openlog(3) is not
called, so the value will depend on system defaults (often the
program name).
Subsystems
dmn Main daemon setup/cleanup/signal handling
mgr IKE_SA manager, handling synchronization for IKE_SA access
ike IKE_SA
chd CHILD_SA
job Jobs queueing/processing and thread pool management
cfg Configuration management and plugins
knl IPsec/Networking kernel interface
net IKE network communication
asn Low-level encoding/decoding (ASN.1, X.509 etc.)
enc Packet encoding/decoding encryption/decryption operations
tls libtls library messages
esp libipsec library messages
lib libstrongwan library messages
tnc Trusted Network Connect
imc Integrity Measurement Collector
imv Integrity Measurement Verifier
pts Platform Trust Service
Loglevels
-1 Absolutely silent
0 Very basic auditing logs, (e.g. SA up/SA down)
1 Generic control flow with errors, a good default to see whats
going on
2 More detailed debugging control flow
3 Including RAW data dumps in Hex
4 Also include sensitive material in dumps, e.g. keys
Example
charon {
filelog {
/var/log/charon.log {
time_format = %b %e %T
append = no
default = 1
}
stderr {
ike = 2
knl = 3
ike_name = yes
}
}
syslog {
# enable logging to LOG_DAEMON, use defaults
daemon {
}
# minimalistic IKE auditing logging to LOG_AUTHPRIV
auth {
default = -1
ike = 0
}
}
}
JOB PRIORITY MANAGEMENT
Some operations in the IKEv2 daemon charon are currently implemented
synchronously and blocking. Two examples for such operations are commu‐
nication with a RADIUS server via EAP-RADIUS, or fetching CRL/OCSP
information during certificate chain verification. Under high load con‐
ditions, the thread pool may run out of available threads, and some
more important jobs, such as liveness checking, may not get executed in
time.
To prevent thread starvation in such situations job priorities were
introduced. The job processor will reserve some threads for higher
priority jobs, these threads are not available for lower priority,
locking jobs.
Implementation
Currently 4 priorities have been defined, and they are used in charon
as follows:
CRITICAL
Priority for long-running dispatcher jobs.
HIGH INFORMATIONAL exchanges, as used by liveness checking (DPD).
MEDIUM Everything not HIGH/LOW, including IKE_SA_INIT processing.
LOW IKE_AUTH message processing. RADIUS and CRL fetching block here
Although IKE_SA_INIT processing is computationally expensive, it is
explicitly assigned to the MEDIUM class. This allows charon to do the
DH exchange while other threads are blocked in IKE_AUTH. To prevent the
daemon from accepting more IKE_SA_INIT requests than it can handle, use
IKE_SA_INIT DROPPING.
The thread pool processes jobs strictly by priority, meaning it will
consume all higher priority jobs before looking for ones with lower
priority. Further, it reserves threads for certain priorities. A prior‐
ity class having reserved n threads will always have n threads avail‐
able for this class (either currently processing a job, or waiting for
one).
Configuration
To ensure that there are always enough threads available for higher
priority tasks, threads must be reserved for each priority class.
libstrongswan.processor.priority_threads.critical [0]
Threads reserved for CRITICAL priority class jobs
libstrongswan.processor.priority_threads.high [0]
Threads reserved for HIGH priority class jobs
libstrongswan.processor.priority_threads.medium [0]
Threads reserved for MEDIUM priority class jobs
libstrongswan.processor.priority_threads.low [0]
Threads reserved for LOW priority class jobs
Let's consider the following configuration:
libstrongswan {
processor {
priority_threads {
high = 1
medium = 4
}
}
}
With this configuration, one thread is reserved for HIGH priority
tasks. As currently only liveness checking and stroke message process‐
ing is done with high priority, one or two threads should be suffi‐
cient.
The MEDIUM class mostly processes non-blocking jobs. Unless your setup
is experiencing many blocks in locks while accessing shared resources,
threads for one or two times the number of CPU cores is fine.
It is usually not required to reserve threads for CRITICAL jobs. Jobs
in this class rarely return and do not release their thread to the
pool.
The remaining threads are available for LOW priority jobs. Reserving
threads does not make sense (until we have an even lower priority).
Monitoring
To see what the threads are actually doing, invoke ipsec statusall.
Under high load, something like this will show up:
worker threads: 2 or 32 idle, 5/1/2/22 working,
job queue: 0/0/1/149, scheduled: 198
From 32 worker threads,
2 are currently idle.
5 are running CRITICAL priority jobs (dispatching from sockets,
etc.).
1 is currently handling a HIGH priority job. This is actually the
thread currently providing this information via stroke.
2 are handling MEDIUM priority jobs, likely IKE_SA_INIT or CRE‐
ATE_CHILD_SA messages.
22 are handling LOW priority jobs, probably waiting for an EAP-
RADIUS response while processing IKE_AUTH messages.
The job queue load shows how many jobs are queued for each priority,
ready for execution. The single MEDIUM priority job will get executed
immediately, as we have two spare threads reserved for MEDIUM class
jobs.
IKE_SA_INIT DROPPING
If a responder receives more connection requests per seconds than it
can handle, it does not make sense to accept more IKE_SA_INIT messages.
And if they are queued but can't get processed in time, an answer might
be sent after the client has already given up and restarted its connec‐
tion setup. This additionally increases the load on the responder.
To limit the responder load resulting from new connection attempts, the
daemon can drop IKE_SA_INIT messages just after reception. There are
two mechanisms to decide if this should happen, configured with the
following options:
charon.init_limit_half_open [0]
Limit based on the number of half open IKE_SAs. Half open
IKE_SAs are SAs in connecting state, but not yet established.
charon.init_limit_job_load [0]
Limit based on the number of jobs currently queued for process‐
ing (sum over all job priorities).
The second limit includes load from other jobs, such as rekeying.
Choosing a good value is difficult and depends on the hardware and
expected load.
The first limit is simpler to calculate, but includes the load from new
connections only. If your responder is capable of negotiating 100 tun‐
nels/s, you might set this limit to 1000. The daemon will then drop new
connection attempts if generating a response would require more than 10
seconds. If you are allowing for a maximum response time of more than
30 seconds, consider adjusting the timeout for connecting IKE_SAs
(charon.half_open_timeout). A responder, by default, deletes an IKE_SA
if the initiator does not establish it within 30 seconds. Under high
load, a higher value might be required.
LOAD TESTS
To do stability testing and performance optimizations, the IKEv2 daemon
charon provides the load-tester plugin. This plugin allows one to setup
thousands of tunnels concurrently against the daemon itself or a remote
host.
WARNING: Never enable the load-testing plugin on productive systems. It
provides preconfigured credentials and allows an attacker to authenti‐
cate as any user.
Options
charon.plugins.load-tester.addrs
Subsection that contains key/value pairs with address pools (in
CIDR notation) to use for a specific network interface e.g. eth0
= 10.10.0.0/16
charon.plugins.load-tester.addrs_keep [no]
Whether to keep dynamic addresses even after the associated SA
got terminated
charon.plugins.load-tester.addrs_prefix [16]
Network prefix length to use when installing dynamic addresses.
If set to -1 the full address is used (i.e. 32 or 128)
charon.plugins.load-tester.ca_dir
Directory to load (intermediate) CA certificates from
charon.plugins.load-tester.child_rekey [600]
Seconds to start CHILD_SA rekeying after setup
charon.plugins.load-tester.delay [0]
Delay between initiatons for each thread
charon.plugins.load-tester.delete_after_established [no]
Delete an IKE_SA as soon as it has been established
charon.plugins.load-tester.digest [sha1]
Digest algorithm used when issuing certificates
charon.plugins.load-tester.dpd_delay [0]
DPD delay to use in load test
charon.plugins.load-tester.dynamic_port [0]
Base port to be used for requests (each client uses a different
port)
charon.plugins.load-tester.eap_password [default-pwd]
EAP secret to use in load test
charon.plugins.load-tester.enable [no]
Enable the load testing plugin
charon.plugins.load-tester.esp [aes128-sha1]
CHILD_SA proposal to use for load tests
charon.plugins.load-tester.fake_kernel [no]
Fake the kernel interface to allow load-testing against self
charon.plugins.load-tester.ike_rekey [0]
Seconds to start IKE_SA rekeying after setup
charon.plugins.load-tester.init_limit [0]
Global limit of concurrently established SAs during load test
charon.plugins.load-tester.initiator [0.0.0.0]
Address to initiate from
charon.plugins.load-tester.initiators [0]
Number of concurrent initiator threads to use in load test
charon.plugins.load-tester.initiator_auth [pubkey]
Authentication method(s) the intiator uses
charon.plugins.load-tester.initiator_id
Initiator ID used in load test
charon.plugins.load-tester.initiator_match
Initiator ID to match against as responder
charon.plugins.load-tester.initiator_tsi
Traffic selector on initiator side, as proposed by initiator
charon.plugins.load-tester.initiator_tsr
Traffic selector on responder side, as proposed by initiator
charon.plugins.load-tester.iterations [1]
Number of IKE_SAs to initiate by each initiator in load test
charon.plugins.load-tester.issuer_cert
Path to the issuer certificate (if not configured a hard-coded
value is used)
charon.plugins.load-tester.issuer_key
Path to private key that is used to issue certificates (if not
configured a hard-coded value is used)
charon.plugins.load-tester.pool
Provide INTERNAL_IPV4_ADDRs from a named pool
charon.plugins.load-tester.preshared_key [default-psk]
Preshared key to use in load test
charon.plugins.load-tester.proposal [aes128-sha1-modp768]
IKE proposal to use in load test
charon.plugins.load-tester.responder [127.0.0.1]
Address to initiation connections to
charon.plugins.load-tester.responder_auth [pubkey]
Authentication method(s) the responder uses
charon.plugins.load-tester.responder_id
Responder ID used in load test
charon.plugins.load-tester.responder_tsi [initiator_tsi]
Traffic selector on initiator side, as narrowed by responder
charon.plugins.load-tester.responder_tsr [initiator_tsr]
Traffic selector on responder side, as narrowed by responder
charon.plugins.load-tester.request_virtual_ip [no]
Request an INTERNAL_IPV4_ADDR from the server
charon.plugins.load-tester.shutdown_when_complete [no]
Shutdown the daemon after all IKE_SAs have been established
charon.plugins.load-tester.socket [unix://${piddir}/charon.ldt]
Socket provided by the load-tester plugin
charon.plugins.load-tester.version [0]
IKE version to use (0 means use IKEv2 as initiator and accept
any version as responder)
Configuration details
For public key authentication, the responder uses the "CN=srv, OU=load-
test, O=strongSwan" identity. For the initiator, each connection
attempt uses a different identity in the form "CN=c1-r1, OU=load-test,
O=strongSwan", where the first number inidicates the client number, the
second the authentication round (if multiple authentication is used).
For PSK authentication, FQDN identities are used. The server uses
srv.strongswan.org, the client uses an identity in the form
c1-r1.strongswan.org.
For EAP authentication, the client uses a NAI in the form
100000000010001@strongswan.org.
To configure multiple authentication, concatenate multiple methods
using, e.g.
initiator_auth = pubkey|psk|eap-md5|eap-aka
The responder uses a hardcoded certificate based on a 1024-bit RSA key.
This certificate additionally serves as CA certificate. A peer uses the
same private key, but generates client certificates on demand signed by
the CA certificate. Install the Responder/CA certificate on the remote
host to authenticate all clients.
To speed up testing, the load tester plugin implements a special
Diffie-Hellman implementation called modpnull. By setting
proposal = aes128-sha1-modpnull
this wicked fast DH implementation is used. It does not provide any
security at all, but allows one to run tests without DH calculation
overhead.
Examples
In the simplest case, the daemon initiates IKE_SAs against itself using
the loopback interface. This will actually establish double the number
of IKE_SAs, as the daemon is initiator and responder for each IKE_SA at
the same time. Installation of IPsec SAs would fails, as each SA gets
installed twice. To simulate the correct behavior, a fake kernel inter‐
face can be enabled which does not install the IPsec SAs at the kernel
level.
A simple loopback configuration might look like this:
charon {
# create new IKE_SAs for each CHILD_SA to simulate
# different clients
reuse_ikesa = no
# turn off denial of service protection
dos_protection = no
plugins {
load-tester {
# enable the plugin
enable = yes
# use 4 threads to initiate connections
# simultaneously
initiators = 4
# each thread initiates 1000 connections
iterations = 1000
# delay each initiation in each thread by 20ms
delay = 20
# enable the fake kernel interface to
# avoid SA conflicts
fake_kernel = yes
}
}
}
This will initiate 4000 IKE_SAs within 20 seconds. You may increase the
delay value if your box can not handle that much load, or decrease it
to put more load on it. If the daemon starts retransmitting messages
your box probably can not handle all connection attempts.
The plugin also allows one to test against a remote host. This might
help to test against a real world configuration. A connection setup to
do stress testing of a gateway might look like this:
charon {
reuse_ikesa = no
threads = 32
plugins {
load-tester {
enable = yes
# 10000 connections, ten in parallel
initiators = 10
iterations = 1000
# use a delay of 100ms, overall time is:
# iterations * delay = 100s
delay = 100
# address of the gateway
remote = 1.2.3.4
# IKE-proposal to use
proposal = aes128-sha1-modp1024
# use faster PSK authentication instead
# of 1024bit RSA
initiator_auth = psk
responder_auth = psk
# request a virtual IP using configuration
# payloads
request_virtual_ip = yes
# enable CHILD_SA every 60s
child_rekey = 60
}
}
}
IKEv2 RETRANSMISSION
Retransmission timeouts in the IKEv2 daemon charon can be configured
globally using the three keys listed below:
charon.retransmit_base [1.8]
charon.retransmit_timeout [4.0]
charon.retransmit_tries [5]
The following algorithm is used to calculate the timeout:
relative timeout = retransmit_timeout * retransmit_base ^ (n-1)
Where n is the current retransmission count.
Using the default values, packets are retransmitted in:
Retransmission Relative Timeout Absolute Timeout
─────────────────────────────────────────────────────
1 4s 4s
2 7s 11s
3 13s 24s
4 23s 47s
5 42s 89s
giving up 76s 165s
FILES
/etc/strongswan.conf
SEE ALSOipsec.conf(5), ipsec.secrets(5), ipsec(8), charon-cmd(8)HISTORY
Written for the strongSwan project ⟨http://www.strongswan.org⟩ by
Tobias Brunner, Andreas Steffen and Martin Willi.
5.1.0 2013-07-22 STRONGSWAN.CONF(5)
