Ubuntu Manpage: ipsec.secrets - secrets for IKE/IPsec authentication

Provided by: libreswan_4.14-1ubuntu2_amd64

NAME

       ipsec.secrets - secrets for IKE/IPsec authentication

DESCRIPTION

The file ipsec.secrets contains a list of secrets. Currently supported secrets are preshared secrets
(PSKs), postquantum preshared keys (PPKs) and XAUTH passwords. As of libreswan version 4.0, the secrets
entries for raw RSA keys are no longer needed and ignored. All private keys from public keypairs (RSA or
ECDSA) are stored completely in the NSS database and :RSA entries are no longer required to locate these.

These secrets are used by pluto(8) , the Libreswan Internet Key Exchange daemon, to authenticate other
hosts. There is another one type of secret, post-quantum preshared keys (PPKs), that are used for
protecting traffic from quantum computer attack.

XAUTH passwords are stored in plaintext in this file. The secrets file should be owned by root, and
permissions should be set to block all access by others. (eg: chmod 600)

The file is a sequence of entries and include directives. Here is an example - each entry or directive
must start at the left margin, but if it continues beyond a single line, each continuation line must be
indented.

# sample /etc/ipsec.secrets file for 10.1.0.1
10.1.0.1 10.2.0.1 : PSK "secret shared by two hosts"
# sample roadwarrior
%any gateway.corp.com : PSK "shared secret with many roadwarriors"
# sample server for roadwarriors
myip %any : PSK "shared secret with many roadwarriors"

# an entry may be split across lines,
# but indentation matters
www.xs4all.nl @www.kremvax.ru
10.6.0.1 10.7.0.1 1.8.0.1 : PSK "secret shared by 5 systems"

# sample entry for static PPK
10.1.0.1 10.2.0.1 : PPKS "PPK_ID_1" "post-quantum preshared key for extra security"

# XAUTH password, used with leftusername=username
@username : XAUTH "password"

include ipsec.*.secrets # get secrets from other files

Each entry in the file is a list of indices, followed by a secret. The two parts are separated by a colon
(:) that is followed by whitespace or a newline.

An index is an IP address, or 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. Be aware that using domain names requires DNS to be functional before the IPsec
tunnel comes up. 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 indices 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, an index of %any will match the peer's IP address if IPV4 and %any6 will match a the peer's IP
address if IPV6.

This file is only read at startup time. If any changes are made to this file, the pluto daemon should be
told to re-read this file using the command ipsec secrets or ipsec auto --rereadsecrets. Note that
currently there is no way to add a specific new entry - it's all or nothing.

Smartcard support has been moved from Libreswan to NSS. The location of these are specified using
leftcert/rightcert entries with a PKIX URI in ipsec.conf. No entry in the secrets file is required for
these.

An additional complexity arises in the case of authentication by preshared secret in IKEv1 Main Mode: 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. IKEv1 Aggressive Mode (aggrmode=yes) can be used to work around this, at the
price of leaking the ID in the clear and allowing a brute force attack against the PSK to be performed
offline. PSKs are the least secure authentication method and should be avoided.

To authenticate a connection between two hosts, the entry that most specifically matches the host and
peer IDs is used. An entry with no index will match any host and peer. More specifically, an entry with
one index will match a host and peer if the index matches the host's ID (the peer isn't considered).
Still more specifically, an entry with multiple indices will match a host and peer if the host ID and
peer ID each match one of the indices. It is acceptable for two entries to be the best match as long as
they agree about the secret.

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 index 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-index entries are best for PSK
authentication.

When running in FIPS mode, PSK's need to comply to a minimum strength requirement depending on the
integrity and PRF algorithm used. It is recommended not to use PSK's shorter then 64 random characters.

The token "XAUTH" indicates an IKEv1 eXtended Authentication password. There should be one index, and it
should be in the @FQDN format. The file will be searched with the XAUTH username, which is usually
provided in the configuration file. XAUTH is otherwise identical to PSK in syntax.

A preshared secret is most conveniently represented as a sequence of characters, delimited by the
double-quote character ("). 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). A preshared secret may also be represented, without quotes, in any of
supported formats.

Currently supported formats are hexadecimal, base64, and characters.

A hexadecimal text value begins with a 0x (or 0X) prefix and continues with two-digit groups of
hexadecimal digits (0-9, and a-f or A-F), each group encoding the value of one binary byte, high-order
digit first. A single _ (underscore) between consecutive groups is ignored, permitting punctuation to
improve readability; doing this every eight digits seems about right.

A base64 text value begins with a 0s (or 0S) prefix and continues with four-digit groups of base64 digits
(A-Z, a-z, 0-9, +, and /), each group encoding the value of three binary bytes as described in section
6.8 of RFC 2045. If flags has the TTODATAV_IGNORESPACE bit on, blanks are ignore (after the prefix). Note
that the last one or two digits of a base64 group can be = to indicate that fewer than three binary bytes
are encoded.

A character text value begins with a 0t (or 0T) prefix and continues with text characters, each being the
value of one binary byte.

Post-quantum preshared keys (PPK) can be static. The token “PPKS” indicates that the following key will
be a PPK. The next token is a PPK_ID that uniquely represents the given PPK. PPK_ID must be represented
as a sequence of characters delimited by the double-quote character ("). The next token is a PPK itself.
The static PPK may be represented in any format that can be used for representing a preshared secret. It
is recommended that the static PPK be at least 256 bits in order to provide real security against quantum
computer attacks.

The first token of an entry must start in the first column of its line. Subsequent tokens must be
separated by whitespace, except for a colon token, which only needs to be followed by whitespace. A
newline is taken as whitespace, but every line of an entry after the first must be indented.

Whitespace at the end of a line is ignored (except in the 0t notation for a key). At the start of line or
after whitespace, # and the following text up to the end of the line is treated as a comment. Within
entries, all lines must be indented (except for lines with no tokens). Outside entries, no line may be
indented (this is to make sure that the file layout reflects its structure).

An include directive causes the contents of the named file to be processed before continuing with the
current file. The filename is subject to "globbing" as in sh(1), so every file with a matching name is
processed. Includes may be nested to a modest depth (10, currently). If the filename doesn't start with a
/, the directory containing the current file is prepended to the name. The include directive is a line
that starts with the word include, followed by whitespace, followed by the filename (which must not
contain whitespace).

FILES

       /etc/ipsec.secrets

HISTORY

       Originally designed for the FreeS/WAN project <https://www.freeswan.org> by D. Hugh Redelmeier. Updated
       for Openswan by Ken Bantoft. Updated for Libreswan by Paul Wouters

       This file originally stored the private part of RSA keys. This was later on moved to the NSS database,
       and all private fields were filled with the CKAID to enable lookup in the NSS database. This was further
       obsoleted in libreswan 4.0 and now the secrets file no longer contains any public key pair information.

BUGS

       If an ID is 0.0.0.0, it will match %any; if it is 0::0, it will match %any6.

AUTHOR