IPSEC.SECRETS(5) strongSwan IPSEC.SECRETS(5)
ipsec.secrets - secrets for IKE/IPsec authentication
The file ipsec.secrets holds a table of secrets. These secrets are used by the strongSwan Internet Key Exchange (IKE) daemons pluto
(IKEv1) and charon (IKEv2) to authenticate other hosts.
It is vital that these secrets be protected. The file should be owned by the super-user, and its permissions should be set to block all
access by others.
The file is a sequence of entries and include directives. Here is an example.
# /etc/ipsec.secrets - strongSwan IPsec secrets file
192.168.0.1 %any : PSK "v+NkxY9LLZvwj4qCC2o/gGrWDF2d21jL"
: RSA moonKey.pem
firstname.lastname@example.org : EAP "x3.dEhgN"
carol : XAUTH "4iChxLT3"
dave : XAUTH "ryftzG4A"
# get secrets from other files
Each entry in the file is a list of optional ID selectors, followed by a secret. The two parts are separated by a colon (:) that is sur-
rounded by whitespace. If no ID selectors are specified the line must start with a colon.
A selector is an IP address, a Fully Qualified Domain Name, user@FQDN, %any or %any6 (other kinds may come). An IP address may be written
in the familiar dotted quad form or as a domain name to be looked up when the file is loaded. In many cases it is a bad idea to use domain
names because the name server may not be running or may be insecure. To denote a Fully Qualified Domain Name (as opposed to an IP address
denoted by its domain name), precede the name with an at sign (@).
Matching IDs with selectors is fairly straightforward: they have to be equal. In the case of a ``Road Warrior'' connection, if an equal
match is not found for the Peer's ID, and it is in the form of an IP address, a selector of %any will match the peer's IP address if IPV4
and %any6 will match a the peer's IP address if IPV6. Currently, the obsolete notation 0.0.0.0 may be used in place of %any.
In IKEv1 an additional complexity arises in the case of authentication by preshared secret: the responder will need to look up the secret
before the Peer's ID payload has been decoded, so the ID used will be the IP address.
To authenticate a connection between two hosts, the entry that most specifically matches the host and peer IDs is used. An entry with no
selectors will match any host and peer. More specifically, an entry with one selector will match a host and peer if the selector matches
the host's ID (the peer isn't considered). Still more specifically, an entry with multiple selectors will match a host and peer if the
host ID and peer ID each match one of the selectors. If the key is for an asymmetric authentication technique (i.e. a public key system
such as RSA), an entry with multiple selectors will match a host and peer even if only the host ID matches a selector (it is presumed that
the selectors are all identities of the host). It is acceptable for two entries to be the best match as long as they agree about the
secret or private key.
Authentication by preshared secret requires that both systems find the identical secret (the secret is not actually transmitted by the IKE
protocol). If both the host and peer appear in the selector list, the same entry will be suitable for both systems so verbatim copying
between systems can be used. This naturally extends to larger groups sharing the same secret. Thus multiple-selector entries are best for
Authentication by public key systems such as RSA requires that each host have its own private key. A host could reasonably use a different
private keys for different interfaces and for different peers. But it would not be normal to share entries between systems. Thus thus no-
selector and one-selector forms of entry often make sense for public key authentication.
The key part of an entry must start with a token indicating the kind of key. The following types of secrets are currently supported:
PSK defines a pre-shared key
RSA defines an RSA private key
ECDSA defines an ECDSA private key
EAP defines EAP credentials
XAUTH defines XAUTH credentials
PIN defines a smartcard PIN
Details on each type of secret are given below.
Whitespace at the end of a line is ignored. At the start of a line or after whitespace, # and the following text up to the end of the line
is treated as a comment.
An include directive causes the contents of the named file to be processed before continuing with the current file. The filename is sub-
ject to ``globbing'' as in sh(1), so every file with a matching name is processed. Includes may be nested to a modest depth (10, cur-
rently). If the filename doesn't start with a /, the directory containing the current file is prepended to the name. The include direc-
tive is a line that starts with the word include, followed by whitespace, followed by the filename (which must not contain whitespace).
TYPES OF SECRETS
[ <selectors> ] : PSK <secret>
A preshared secret is most conveniently represented as a sequence of characters, delimited by double-quote characters ("). The
sequence cannot contain a newline or double-quote. Strictly speaking, the secret is actually the sequence of bytes that is used in
the file to represent the sequence of characters (excluding the delimiters).
[ <selectors> ] : RSA <private key file> [ <passphrase> | %prompt ]
[ <selectors> ] : ECDSA <private key file> [ <passphrase> | %prompt ]
For the private key file both absolute paths or paths relative to /etc/ipsec.d/private are accepted. If the private key file is
encrypted, the passphrase must be defined. Instead of a passphrase %prompt can be used which then causes the daemons to ask the user
for the password whenever it is required to decrypt the key.
<user id> : EAP <secret>
As with PSK secrets the secret is a sequence of characters, delimited by double-quote characters (").
EAP secrets are IKEv2 only.
[ <servername> ] <username> : XAUTH <password>
XAUTH secrets are IKEv1 only.
: PIN <smartcard selector> <pin code> | %prompt
IKEv1 uses the format %smartcard[<slot nr>[:<key id>]] to specify the smartcard selector (e.g. %smartcard1:50). The IKEv2 daemon
supports multiple modules with the format %smartcard[<slot nr>[@<module>]]:<keyid> , but always requires a keyid to uniquely select
the correct key. Instead of specifying the pin code statically, %prompt can be specified, which causes the daemons to ask the user
for the pin code.
ipsec.conf(5), strongswan.conf(5), ipsec(8)
Originally written for the FreeS/WAN project by D. Hugh Redelmeier. Updated and extended for the strongSwan project
<http://www.strongswan.org> by Tobias Brunner and Andreas Steffen.
If an ID is 0.0.0.0, it will match %any; if it is 0::0, it will match %any6.
4.5.2 2010-05-30 IPSEC.SECRETS(5)