|
|
IPSEC_SET_POLICY(3)
Contents
|
ipsec_set_policy, ipsec_get_policylen, ipsec_dump_policy -- manipulate
IPsec policy specification structure from readable string
IPsec Policy Control Library (libipsec, -lipsec)
#include <netinet6/ipsec.h>
char *
ipsec_set_policy(char *policy, int len);
int
ipsec_get_policylen(char *buf);
char *
ipsec_dump_policy(char *buf, char *delim);
The ipsec_set_policy() function generates IPsec policy specification
structure, namely struct sadb_x_policy and/or struct sadb_x_ipsecrequest
from human-readable policy specification. Policy specification must be
given as C string policy and length len of policy. The
ipsec_set_policy() function will return the buffer of IPsec policy specification
structure. The buffer is dynamically allocated, and must be
freed by the caller by calling free(3).
You may want the length of the generated buffer such when calling
setsockopt(2). The ipsec_get_policylen() function will return the
length.
The ipsec_dump_policy() function converts IPsec policy structure into
readable form. Therefore, ipsec_dump_policy() can be regarded as inverse
conversion of ipsec_set_policy(). buf points to an IPsec policy structure,
struct sadb_x_policy. delim is a delimiter string, which is usually
a blank character. If you set delim to NULL, single whitespace is
assumed. The ipsec_dump_policy() function returns a pointer to dynamically
allocated string. It is caller's responsibility to reclaim the
region, by using free(3).
policy is formatted as either of the following:
direction discard
direction must be in or out. direction specifies which direction
the policy needs to be applied. With discard policy, packets
will be dropped if they match the policy.
direction entrust
entrust means to consult to SPD defined by setkey(8).
direction bypass
bypass means to be bypassed the IPsec processing. (packet will
be transmitted in clear). This is for privileged socket.
direction ipsec request ...
ipsec means that the matching packets are subject to IPsec processing.
ipsec can be followed by one or more request string,
which is formatted as below:
protocol / mode / src - dst [/level]
protocol is either ah, esp or ipcomp.
mode is either transport or tunnel.
src and dst specifies IPsec endpoint. src always means
``sending node'' and dst always means ``receiving
node''. Therefore, when direction is in, dst is this
node and src is the other node (peer). If mode is
transport, Both src and dst can be omitted.
level must be set to one of the following: default,
use, require or unique. default means that the kernel
should consult the system default policy defined by
sysctl(8), such as net.inet.ipsec.esp_trans_deflev.
See ipsec(4) regarding the system default. use means
that a relevant SA can be used when available, since
the kernel may perform IPsec operation against packets
when possible. In this case, packets can be transmitted
in clear (when SA is not available), or encrypted
(when SA is available). require means that a relevant
SA is required, since the kernel must perform IPsec
operation against packets. unique is the same as
require, but adds the restriction that the SA for outbound
traffic is used only for this policy. You may
need the identifier in order to relate the policy and
the SA when you define the SA by manual keying. You
can put the decimal number as the identifier after
unique like unique: number. number must be between 1
and 32767 . If the request string is kept unambiguous,
level and slash prior to level can be omitted. However,
it is encouraged to specify them explicitly to
avoid unintended behaviors. If level is omitted, it
will be interpreted as default.
Note that there is a bit difference of specification from setkey(8). In
specification by setkey(8), both entrust and bypass are not used. Refer
to setkey(8) for detail.
Here are several examples (long lines are wrapped for readability):
in discard
out ipsec esp/transport//require
in ipsec ah/transport//require
out ipsec esp/tunnel/10.1.1.2-10.1.1.1/use
in ipsec ipcomp/transport//use
esp/transport//use
The ipsec_set_policy() function returns a pointer to the allocated buffer
of policy specification if successful; otherwise a NULL pointer is
returned. The ipsec_get_policylen() function returns with positive value
(meaning the buffer size) on success, and negative value on errors. The
ipsec_dump_policy() function returns a pointer to dynamically allocated
region on success, and NULL on errors.
ipsec_strerror(3), ipsec(4), setkey(8)
The functions first appeared in WIDE/KAME IPv6 protocol stack kit.
IPv6 and IPsec support based on the KAME Project (http://www.kame.net/)
stack was initially integrated into FreeBSD 4.0
FreeBSD 5.2.1 May 5, 1998 FreeBSD 5.2.1 [ Back ] |
