The optional
ipsec.conf file
specifies most configuration and control information for the
Openswan IPsec subsystem.
(The major exception is secrets for authentication;
see
ipsec.secrets(5) .) Its contents are not security-sensitive
unless manual keying is being done for more than just testing,
in which case the encryption/authentication keys in the
descriptions for the manually-keyed connections are very sensitive
(and those connection descriptions
are probably best kept in a separate file,
via the include facility described below).
The file is a text file, consisting of one or more
sections . White space followed by
# followed by anything to the end of the line
is a comment and is ignored,
as are empty lines which are not within a section.
A line which contains
include and a file name, separated by white space,
is replaced by the contents of that file,
preceded and followed by empty lines.
If the file name is not a full pathname,
it is considered to be relative to the directory containing the
including file.
Such inclusions can be nested.
Only a single filename may be supplied, and it may not contain white space,
but it may include shell wildcards (see
sh(1) ); for example:
include ipsec.*.conf
The intention of the include facility is mostly to permit keeping
information on connections, or sets of connections,
separate from the main configuration file.
This permits such connection descriptions to be changed,
copied to the other security gateways involved, etc.,
without having to constantly extract them from the configuration
file and then insert them back into it.
Note also the
also and
alsoflip parameters (described below) which permit splitting a single logical section
(e.g. a connection description) into several actual sections.
The first significant line of the file must specify the version
of this specification that it conforms to:
version 2
A section
begins with a line of the form:
type name
where
type indicates what type of section follows, and
name is an arbitrary name which distinguishes the section from others
of the same type.
(Names must start with a letter and may contain only
letters, digits, periods, underscores, and hyphens.)
All subsequent non-empty lines
which begin with white space are part of the section;
comments within a section must begin with white space too.
There may be only one section of a given type with a given name.
Lines within the section are generally of the form
parameter=value
(note the mandatory preceding white space).
There can be white space on either side of the
= . Parameter names follow the same syntax as section names,
and are specific to a section type.
Unless otherwise explicitly specified,
no parameter name may appear more than once in a section.
An empty
value stands for the system default value (if any) of the parameter,
i.e. it is roughly equivalent to omitting the parameter line entirely.
A
value may contain white space only if the entire
value is enclosed in double quotes (");
a
valuecannot itself contain a double quote,
nor may it be continued across more than one line.
Numeric values are specified to be either an ``integer''
(a sequence of digits) or a ``decimal number''
(sequence of digits optionally followed by `.' and another sequence of digits).
There is currently one parameter which is available in any type of
section:
also
the value is a section name;
the parameters of that section are appended to this section,
as if they had been written as part of it.
The specified section must exist, must follow the current one,
and must have the same section type.
(Nesting is permitted,
and there may be more than one
also in a single section,
although it is forbidden to append the same section more than once.)
This allows, for example, keeping the encryption keys
for a connection in a separate file
from the rest of the description, by using both an
also parameter and an
include line.
(Caution, see BUGS below for some restrictions.)
alsoflip
can be used in a
conn section.
It acts like an
also that flips the referenced section's entries left-for-right.
Parameter names beginning with
x- (or
X- , or
x_ , or
X_ ) are reserved for user extensions and will never be assigned meanings
by IPsec.
Parameters with such names must still observe the syntax rules
(limits on characters used in the name;
no white space in a non-quoted value;
no newlines or double quotes within the value).
All other as-yet-unused parameter names are reserved for future IPsec
improvements.
A section with name
%default specifies defaults for sections of the same type.
For each parameter in it,
any section of that type which does not have a parameter of the same name
gets a copy of the one from the
%default section.
There may be multiple
%default sections of a given type,
but only one default may be supplied for any specific parameter name,
and all
%default sections of a given type must precede all non-c
%default sections of that type.
%default sections may not contain
also or
alsoflip parameters.
Currently there are two types of section:
a
config section specifies general configuration information for IPsec,
while a
conn section specifies an IPsec connection.
CONN SECTIONS
A
conn section contains a
"connection specification" , defining a network connection to be made using IPsec.
The name given is arbitrary, and is used to identify the connection to
ipsec_auto(8) and
ipsec_manual(8) . Here's a simple example:
A note on terminology...
In automatic keying, there are two kinds of communications going on:
transmission of user IP packets, and gateway-to-gateway negotiations for
keying, rekeying, and general control.
The data path (a set of ``IPsec SAs'') used for user packets is herein
referred to as the ``connection'';
the path used for negotiations (built with ``ISAKMP SAs'') is referred to as
the ``keying channel''.
To avoid trivial editing of the configuration file to suit it to each system
involved in a connection,
connection specifications are written in terms of
left and
right participants,
rather than in terms of local and remote.
Which participant is considered
left or
right is arbitrary;
IPsec figures out which one it is being run on based on internal information.
This permits using identical connection specifications on both ends.
There are cases where there is no symmetry; a good convention is to
use
left for the local side and
right for the remote side (the first letters are a good mnemonic).
Many of the parameters relate to one participant or the other;
only the ones for
left are listed here, but every parameter whose name begins with
left has a
right counterpart,
whose description is the same but with
left and
right reversed.
Parameters are optional unless marked ``(required)'';
a parameter required for manual keying need not be included for
a connection which will use only automatic keying, and vice versa.
"CONN PARAMETERS: GENERAL" The following parameters are relevant to both automatic and manual keying.
Unless otherwise noted,
for a connection to work,
in general it is necessary for the two ends to agree exactly
on the values of these parameters.
type
the type of the connection; currently the accepted values
are
tunnel (the default)
signifying a host-to-host, host-to-subnet, or subnet-to-subnet tunnel;
transport , signifying host-to-host transport mode;
passthrough , signifying that no IPsec processing should be done at all;
drop , signifying that packets should be discarded; and
reject , signifying that packets should be discarded and a diagnostic ICMP returned.
left
(required)
the IP address of the left participant's public-network interface,
in any form accepted by
ipsec_ttoaddr(3) or one of several magic values.
If it is
%defaultroute , and
the
config setup section's,
interfaces specification contains
%defaultroute, left will be filled in automatically with the local address
of the default-route interface (as determined at IPsec startup time);
this also overrides any value supplied for
leftnexthop . (Either
left or
right may be
%defaultroute , but not both.)
The value
%any signifies an address to be filled in (by automatic keying) during
negotiation.
The value
%opportunistic signifies that both
left and
leftnexthop are to be filled in (by automatic keying) from DNS data for
left 's client.
The values
%group and
%opportunisticgroup makes this a policy group conn: one that will be instantiated
into a regular or opportunistic conn for each CIDR block listed in the
policy group file with the same name as the conn.
leftsubnet
private subnet behind the left participant, expressed as
network/netmask
(actually, any form acceptable to
ipsec_ttosubnet(3) );if omitted, essentially assumed to be left/32,
signifying that the left end of the connection goes to the left participant only
leftnexthop
next-hop gateway IP address for the left participant's connection
to the public network;
defaults to
%direct (meaning
right ). If the value is to be overridden by the
left=%defaultroute method (see above),
an explicit value must
not be given.
If that method is not being used,
but
leftnexthop is
%defaultroute , and
interfaces=%defaultroute is used in the
config setup section,
the next-hop gateway address of the default-route interface
will be used.
The magic value
%direct signifies a value to be filled in (by automatic keying)
with the peer's address.
Relevant only locally, other end need not agree on it.
leftupdown
what ``updown'' script to run to adjust routing and/or firewalling
when the status of the connection
changes (default
"ipsec _updown" ). May include positional parameters separated by white space
(although this requires enclosing the whole string in quotes);
including shell metacharacters is unwise.
See
ipsec_pluto(8) for details.
Relevant only locally, other end need not agree on it.
If one or both security gateways are doing forwarding firewalling
(possibly including masquerading),
and this is specified using the firewall parameters,
tunnels established with IPsec are exempted from it
so that packets can flow unchanged through the tunnels.
(This means that all subnets connected in this manner must have
distinct, non-overlapping subnet address blocks.)
This is done by the default
updown script (see
ipsec_pluto(8) ).
"CONN PARAMETERS: AUTOMATIC KEYING" The following parameters are relevant only to automatic keying,
and are ignored in manual keying.
Unless otherwise noted,
for a connection to work,
in general it is necessary for the two ends to agree exactly
on the values of these parameters.
keyexchange
method of key exchange;
the default and currently the only accepted value is
ike
auto
what operation, if any, should be done automatically at IPsec startup;
currently-accepted values are
add (signifying an
ipsec auto --add ), route (signifying that plus an
ipsec auto --route ), start (signifying that plus an
ipsec auto --up ), manual (signifying an
ipsec manual --up ), and
ignore (also the default) (signifying no automatic startup operation).
See the
config setup discussion below.
Relevant only locally, other end need not agree on it
(but in general, for an intended-to-be-permanent connection,
both ends should use
auto=start to ensure that any reboot causes immediate renegotiation).
auth
whether authentication should be done as part of
ESP encryption, or separately using the AH protocol;
acceptable values are
esp (the default) and
ah .
authby
how the two security gateways should authenticate each other;
acceptable values are
secret for shared secrets,
rsasig for RSA digital signatures (the default),
secret|rsasig for either, and
never if negotiation is never to be attempted or accepted (useful for shunt-only conns).
Digital signatures are superior in every way to shared secrets.
leftid
how
the left participant
should be identified for authentication;
defaults to
left . Can be an IP address (in any
ipsec_ttoaddr(3) syntax)
or a fully-qualified domain name preceded by
@ (which is used as a literal string and not resolved).
The magic value
%myid stands for the current setting of myid.
This is set in config setup or by ipsec_whack(8) ), or, if not set,
it is the IP address in %defaultroute (if that is supported by a TXT record in its reverse domain), or otherwise
it is the system's hostname (if that is supported by a TXT record in its forward domain), or otherwise it is undefined.
leftrsasigkey
the left participant's
public key for RSA signature authentication,
in RFC 2537 format using
ipsec_ttodata(3) encoding.
The magic value
%none means the same as not specifying a value (useful to override a default).
The value
%dnsondemand (the default)
means the key is to be fetched from DNS at the time it is needed.
The value
%dnsonload means the key is to be fetched from DNS at the time
the connection description is read from
ipsec.conf ; currently this will be treated as
%none if
right=%any or
right=%opportunistic . The value
%dns is currently treated as
%dnsonload but will change to
%dnsondemand in the future.
The identity used for the left participant
must be a specific host, not
%any or another magic value.
The value
%cert will load the information required from a certificate defined in
%leftcert and automatically define leftid for you.
Caution: if two connection descriptions
specify different public keys for the same
leftid , confusion and madness will ensue.
leftrsasigkey2
if present, a second public key.
Either key can authenticate the signature, allowing for key rollover.
leftcert
If you are using
leftrsasigkey=%cert this defines the certificate you would like to use. It should point to a X.509
encoded certificate file. If you do not specify a full pathname, by default it
will look in /etc/ipsec.d/certs.
leftsendcert
This option configures when Openswan will send X.509 certificates to the remote
host. Acceptable values are
yes|always (signifying that we should always send a certificate),
ifasked (signifying that we should send a certificate if the remote end asks for it), and
no|never (signifying that we will never send a X.509 certificate).
The default for this option is
ifasked which may break compatibility with other vendor's IPSec implementations, such as
Cisco and SafeNet. If you find that you are getting errors about no ID/Key found,
you likely need to set this to
always.
aggrmode
Use aggressive mode ISAKMP negotiation. The default is
main mode. Aggressive mode is less secure than main mode as it reveals
your identity to an eavesdropper, but is needed to support road warriors
using PSK keys or to interoperate with other buggy implementations insisting
on using aggressive mode.
xauth
Use XAUTH / Mode Config for this connection. This uses PAM for authentication
currently, and it not well documented. Use the source :) Acceptable values are
yes or
no (the default).
dpddelay
Set the delay (in seconds) between Dead Peer Dectection
(RFC 3706) keepalives (R_U_THERE, R_U_THERE_ACK)
that are sent for this connection (default
30 seconds). If dpdtimeout is set, but not dpddelay, dpddelay will be set
to the default.
dpdtimeout
Set the length of time (in seconds) we will idle without hearing either an
R_U_THERE poll from our peer, or an R_U_THERE_ACK reply. After this period
has elapsed with no response and no traffic, we will declare the peer dead,
and remove the SA (default
120 seconds). If dpddelay is set, but not dpdtimeout, dpdtimeout will be set
to the default.
dpdaction
When a DPD enabled peer is declared dead, what action should be taken.
hold (default) means the eroute will be put into %hold status, while clear means the eroute and SA with both be cleared. dpdaction=clear is really only usefull on the server of a Road Warrior config.
pfs
whether Perfect Forward Secrecy of keys is desired on the connection's
keying channel
(with PFS, penetration of the key-exchange protocol
does not compromise keys negotiated earlier);
acceptable values are
yes (the default)
and
no .
keylife
how long a particular instance of a connection
(a set of encryption/authentication keys for user packets) should last,
from successful negotiation to expiry;
acceptable values are an integer optionally followed by
s (a time in seconds)
or a decimal number followed by
m , h , or
d (a time
in minutes, hours, or days respectively)
(default
8.0h , maximum
24h ). Normally, the connection is renegotiated (via the keying channel)
before it expires.
The two ends need not exactly agree on
keylife , although if they do not,
there will be some clutter of superseded connections on the end
which thinks the lifetime is longer.
rekey
whether a connection should be renegotiated when it is about to expire;
acceptable values are
yes (the default)
and
no . The two ends need not agree,
but while a value of
no prevents Pluto from requesting renegotiation,
it does not prevent responding to renegotiation requested from the other end,
so
no will be largely ineffective unless both ends agree on it.
rekeymargin
how long before connection expiry or keying-channel expiry
should attempts to
negotiate a replacement
begin; acceptable values as for
keylife (default
9m ). Relevant only locally, other end need not agree on it.
rekeyfuzz
maximum percentage by which
rekeymargin should be randomly increased to randomize rekeying intervals
(important for hosts with many connections);
acceptable values are an integer,
which may exceed 100,
followed by a `%'
(default set by
ipsec_pluto(8) , currently
100% ). The value of
rekeymargin , after this random increase,
must not exceed
keylife . The value
0% will suppress time randomization.
Relevant only locally, other end need not agree on it.
keyingtries
how many attempts (a whole number or %forever) should be made to
negotiate a connection, or a replacement for one, before giving up
(default
%forever ). The value %forever
means ``never give up'' (obsolete: this can be written 0).
Relevant only locally, other end need not agree on it.
ikelifetime
how long the keying channel of a connection (buzzphrase: ``ISAKMP SA'')
should last before being renegotiated;
acceptable values as for
keylife (default set by
ipsec_pluto(8) , currently
1h , maximum
8h ). The two-ends-disagree case is similar to that of
keylife .
compress
whether IPComp compression of content is proposed on the connection
(link-level compression does not work on encrypted data,
so to be effective, compression must be done before encryption);
acceptable values are
yesand
no (the default).
The two ends need not agree.
A value of
yes causes IPsec to propose both compressed and uncompressed,
and prefer compressed.
A value of
no prevents IPsec from proposing compression;
a proposal to compress will still be accepted.
disablearrivalcheck
whether KLIPS's normal tunnel-exit check
(that a packet emerging from a tunnel has plausible addresses in its header)
should be disabled;
acceptable values are
yes and
no (the default).
Tunnel-exit checks improve security and do not break any normal configuration.
Relevant only locally, other end need not agree on it.
failureshunt
what to do with packets when negotiation fails.
The default is
none : no shunt;
passthrough , drop , and
reject have the obvious meanings.
"CONN PARAMETERS: MANUAL KEYING" The following parameters are relevant only to manual keying,
and are ignored in automatic keying.
Unless otherwise noted,
for a connection to work,
in general it is necessary for the two ends to agree exactly
on the values of these parameters.
A manually-keyed
connection must specify at least one of AH or ESP.
spi
(this or
spibase required for manual keying)
the SPI number to be used for the connection (see
ipsec_manual(8) ); must be of the form 0xhex,
where
hexis one or more hexadecimal digits
(note, it will generally be necessary to make
spi at least
0x100 to be acceptable to KLIPS,
and use of SPIs in the range
0x100 - 0xfff is recommended)
spibase
(this or
spi required for manual keying)
the base number for the SPIs to be used for the connection (see
ipsec_manual(8) ); must be of the form 0xhex0,
where
hexis one or more hexadecimal digits
(note, it will generally be necessary to make
spibase at least
0x100 for the resulting SPIs
to be acceptable to KLIPS,
and use of numbers in the range
0x100 - 0xff0 is recommended)
esp
ESP encryption/authentication algorithm to be used
for the connection, e.g.
3des-md5-96 (must be suitable as a value of
ipsec_spi(8) 's --esp option);
default is not to use ESP
espenckey
ESP encryption key
(must be suitable as a value of
ipsec_spi(8) 's --enckey option)
(may be specified separately for each direction using
leftespenckey (leftward SA)
and
rightespenckey parameters)
espauthkey
ESP authentication key
(must be suitable as a value of
ipsec_spi(8) 's --authkey option)
(may be specified separately for each direction using
leftespauthkey (leftward SA)
and
rightespauthkey parameters)
espreplay_window
ESP replay-window setting,
an integer from
0 (the
ipsec_manual default, which turns off replay protection) to
64 ; relevant only if ESP authentication is being used
leftespspi
SPI to be used for the leftward ESP SA, overriding
automatic assignment using
spi or
spibase ; typically a hexadecimal number beginning with
0x
ah
AH authentication algorithm to be used
for the connection, e.g.
hmac-md5-96 (must be suitable as a value of
ipsec_spi(8) 's --ah option);
default is not to use AH
ahkey
(required if
ah is present) AH authentication key
(must be suitable as a value of
ipsec_spi(8) 's --authkey option)
(may be specified separately for each direction using
leftahkey (leftward SA)
and
rightahkey parameters)
ahreplay_window
AH replay-window setting,
an integer from
0 (the
ipsec_manual default, which turns off replay protection) to
64
leftahspi
SPI to be used for the leftward AH SA, overriding
automatic assignment using
spi or
spibase ; typically a hexadecimal number beginning with
0x
CONFIG SECTIONS
At present, the only
config section known to the IPsec software is the one named
setup , which contains information used when the software is being started
(see
ipsec_setup(8) ). Here's an example:
Parameters are optional unless marked ``(required)''.
The currently-accepted
parameter names in a
config setup section are:
myid
the identity to be used for
%myid . %myid is used in the implicit policy group conns and can be used as
an identity in explicit conns.
If unspecified,
%myid is set to the IP address in %defaultroute (if that is supported by a TXT record in its reverse domain), or otherwise
the system's hostname (if that is supported by a TXT record in its forward domain), or otherwise it is undefined.
An explicit value generally starts with ``@''.
interfaces
virtual and physical interfaces for IPsec to use:
a single
virtual=physical pair, a (quoted!) list of pairs separated
by white space, or
%none .One of the pairs may be written as
%defaultroute , which means: find the interface d that the default route points to,
and then act as if the value was ``ipsec0=d''.
%defaultrouteis the default;
%none must be used to denote no interfaces.
If
%defaultroute is used (implicitly or explicitly)
information about the default route and its interface is noted for
use by
ipsec_manual(8) and
ipsec_auto(8) .)
forwardcontrol
whether
setup should turn IP forwarding on
(if it's not already on) as IPsec is started,
and turn it off again (if it was off) as IPsec is stopped;
acceptable values are
yes and (the default)
no . For this to have full effect, forwarding must be
disabled before the hardware interfaces are brought
up (e.g.,
net.ipv4.ip_forward\ =\ 0 in Red Hat 6.x
/etc/sysctl.conf ), because IPsec doesn't get control early enough to do that.
rp_filter
whether and how
setup should adjust the reverse path filtering mechanism for the
physical devices to be used.
Values are %unchanged (to leave it alone)
or 0, 1, 2 (values to set it to).
/proc/sys/net/ipv4/conf/PHYS/rp_filter
is badly documented; it must be 0 in many cases
for ipsec to function.
The default value for the parameter is 0.
syslog
the
syslog(2) ``facility'' name and priority to use for
startup/shutdown log messages,
default
daemon.error .
klipsdebug
how much KLIPS debugging output should be logged.
An empty value,
or the magic value
none , means no debugging output (the default).
The magic value
all means full output.
Otherwise only the specified types of output
(a quoted list, names separated by white space) are enabled;
for details on available debugging types, see
ipsec_klipsdebug(8) .
plutodebug
how much Pluto debugging output should be logged.
An empty value,
or the magic value
none , means no debugging output (the default).
The magic value
all means full output.
Otherwise only the specified types of output
(a quoted list, names without the
--debug- prefix,
separated by white space) are enabled;
for details on available debugging types, see
ipsec_pluto(8) .
plutoopts
additional options to pass to pluto upon startup. See
ipsec_pluto(8) .
plutostderrlog
do not use syslog, but rather log to stderr, and direct stderr to the
argument file.
dumpdir
in what directory should things started by
setup (notably the Pluto daemon) be allowed to
dump core?
The empty value (the default) means they are not
allowed to.
manualstart
which manually-keyed connections to set up at startup
(empty, a name, or a quoted list of names separated by white space);
see
ipsec_manual(8) . Default is none.
pluto
whether to start Pluto or not;
Values are
yes (the default)
or
no (useful only in special circumstances).
plutowait
should Pluto wait for each
negotiation attempt that is part of startup to
finish before proceeding with the next?
Values are
yes or
no (the default).
prepluto
shell command to run before starting Pluto
(e.g., to decrypt an encrypted copy of the
ipsec.secrets file).
It's run in a very simple way;
complexities like I/O redirection are best hidden within a script.
Any output is redirected for logging,
so running interactive commands is difficult unless they use
/dev/tty or equivalent for their interaction.
Default is none.
postpluto
shell command to run after starting Pluto
(e.g., to remove a decrypted copy of the
ipsec.secrets file).
It's run in a very simple way;
complexities like I/O redirection are best hidden within a script.
Any output is redirected for logging,
so running interactive commands is difficult unless they use
/dev/tty or equivalent for their interaction.
Default is none.
fragicmp
whether a tunnel's need to fragment a packet should be reported
back with an ICMP message,
in an attempt to make the sender lower his PMTU estimate;
acceptable values are
yes (the default)
and
no .
hidetos
whether a tunnel packet's TOS field should be set to
0 rather than copied from the user packet inside;
acceptable values are
yes (the default)
and
no .
uniqueids
whether a particular participant ID should be kept unique,
with any new (automatically keyed)
connection using an ID from a different IP address
deemed to replace all old ones using that ID;
acceptable values are
yes (the default)
and
no . Participant IDs normally are unique,
so a new (automatically-keyed) connection using the same ID is
almost invariably intended to replace an old one.
overridemtu
value that the MTU of the ipsecn interface(s) should be set to,
overriding IPsec's (large) default.
This parameter is needed only in special situations.
nat_traversal
whether to accept/offer to support NAT (NAPT, also known as "IP Masqurade")
workaround for IPsec. Acceptable values are:
yes and
no (the default).
This parameter may eventually become per-connection.
IMPLICIT CONNS
The system automatically defines several conns to implement
default policy groups. Each can be overridden by explicitly
defining a new conn with the same name. If the new conn has auto=ignore,
the definition is suppressed.
These conns are not affected by anything in conn %default.
They will only work if %defaultroute works.
The leftid will be the interfaces IP address; this
requires that reverse DNS records be set up properly.
The implicit conns are defined after all others. It is
appropriate and reasonable to use also=private-or-clear
(for example) in any other opportunistic conn.
POLICY GROUP FILES
The optional files under
/etc/ipsec.d/policy , including
may contain policy group configuration information to
supplement
ipsec.conf . Their contents are not security-sensitive.
These files are text files.
Each consists of a list of CIDR blocks, one per line.
White space followed by # followed by anything to the end of the line
is a comment and is ignored, as are empty lines.
A connection in
/etc/ipsec.conf which has
right=%group or
right=%opportunisticgroup is a policy group connection.
When a policy group file of the same name is loaded, with
ipsec auto --rereadgroups
or at system start, the connection is instantiated such that each
CIDR block serves as an instance's
right value. The system treats the
resulting instances as normal connections.
For example, given a suitable connection definition
private , and the file
/etc/ipsec.d/policy/private with an entry 192.0.2.3,
the system creates a connection instance
private#192.0.2.3. This connection inherits all details from
private , except that its right client is 192.0.2.3.
DEFAULT POLICY GROUPS
The standard Openswan install includes several policy groups
which provide a way of classifying possible peers into IPsec security classes:
private (talk encrypted only),
private-or-clear (prefer encryption),
clear-or-private (respond to requests for encryption),
clear and
block . Implicit policy groups apply to the local host only,
and are implemented by the
IMPLICIT CONNECTIONS described above.
CHOOSING A CONNECTION
When choosing a connection to apply to an outbound packet caught with a
%trap, the system prefers the one with the most specific eroute that
includes the packet's source and destination IP addresses.
Source subnets are examined before destination subnets.
For initiating, only routed connections are considered. For responding,
unrouted but added connections are considered.
When choosing a connection to use to respond to a negotiation which
doesn't match an ordinary conn, an opportunistic connection
may be instantiated. Eventually, its instance will be /32 -> /32, but
for earlier stages of the negotiation, there will not be enough
information about the client subnets to complete the instantiation.
Designed for the FreeS/WAN project
<http://www.freeswan.org>
by Henry Spencer.
BUGS
When
type or
failureshunt is set to
drop or
reject, Openswan blocks outbound packets using eroutes, but assumes inbound
blocking is handled by the firewall. Openswan offers firewall hooks
via an ``updown'' script. However, the default
ipsec _updown provides no help in controlling a modern firewall.
Including attributes of the keying channel
(authentication methods,
ikelifetime , etc.)
as an attribute of a connection,
rather than of a participant pair, is dubious and incurs limitations.
Ipsec_manual is not nearly as generous about the syntax of subnets,
addresses, etc. as the usual Openswan user interfaces.
Four-component dotted-decimal must be used for all addresses.
It
is smart enough to translate bit-count netmasks to dotted-decimal form.
It would be good to have a line-continuation syntax,
especially for the very long lines involved in
RSA signature keys.
The ability to specify different identities,
authby , and public keys for different automatic-keyed connections
between the same participants is misleading;
this doesn't work dependably because the identity of the participants
is not known early enough.
This is especially awkward for the ``Road Warrior'' case,
where the remote IP address is specified as
0.0.0.0 , and that is considered to be the ``participant'' for such connections.
In principle it might be necessary to control MTU on an
interface-by-interface basis,
rather than with the single global override that
overridemtu provides.
A number of features which could be implemented in
both manual and automatic keying
actually are not yet implemented for manual keying.
This is unlikely to be fixed any time soon.
If conns are to be added before DNS is available,
left=FQDN,
leftnextop=FQDN,
and
leftrsasigkey=%dnsonload will fail.
ipsec_pluto(8) does not actually use the public key for our side of a conn but it
isn't generally known at a add-time which side is ours (Road Warrior
and Opportunistic conns are currently exceptions).
The myid option does not affect explicit ipsec auto --add or ipsec auto --replace commands for implicit conns.