table of contents
IPSEC_SET_POLICY(3) | Library Functions Manual | IPSEC_SET_POLICY(3) |
NAME¶
ipsec_set_policy, ipsec_get_policylen, ipsec_dump_policy — manipulate IPsec policy specification structure from human-readable policy stringLIBRARY¶
IPsec Policy Control Library (libipsec, -lipsec)SYNOPSIS¶
#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);
DESCRIPTION¶
ipsec_set_policy() generates an IPsec policy specification structure, namelystruct sadb_x_policy
and/or
struct sadb_x_ipsecrequest
from a human-readable
policy specification. The policy specification must be given as a C string
policy and its length len.
ipsec_set_policy() will return a buffer with the
corresponding IPsec policy specification structure. The buffer is dynamically
allocated, and must be free(3)'d by the caller.
You can get the length of the generated buffer with
ipsec_get_policylen() (i.e. for calling
setsockopt(2)).
ipsec_dump_policy() converts an IPsec policy structure into
human-readable form. Therefore, ipsec_dump_policy() can be
regarded as the inverse function to 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
, a single
whitespace is assumed. ipsec_dump_policy() returns a pointer
to a dynamically allocated string. It is the caller's responsibility to
free(3) it.
policy is formatted as either of the following:
- direction
[priority specification]
discard
- direction must be
in
,out
, orfwd
. direction specifies in which direction the policy needs to be applied. The non-standard directionfwd
is substituted within
on platforms which do not support forward policies. priority specification is used to control the placement of the policy within the SPD. The policy position is determined by a signed integer where higher priorities indicate the policy is placed closer to the beginning of the list and lower priorities indicate the policy is placed closer to the end of the list. Policies with equal priorities are added at the end of the group of such policies. Priority can only be specified when libipsec has been compiled against kernel headers that support policy priorities (Linux >= 2.6.6). It takes one of the following formats:- {priority,prio} offset
- offset is an integer in the range -2147483647..214783648.
- {priority,prio} base {+,-} offset
- base is either
low (-1073741824)
,def (0)
, orhigh (1073741824)
. offset is an unsigned integer. It can be up to 1073741824 for positive offsets, and up to 1073741823 for negative offsets.
discard
policy, packets will be dropped if they match the policy. - direction
[priority specification]
entrust
entrust
means to consult the SPD defined by setkey(8).- direction
[priority specification]
bypass
bypass
means to bypass the IPsec processing. (the packet will be transmitted in clear). This is for privileged sockets.- direction
[priority specification]
ipsec
request ... ipsec
means that the matching packets are subject to IPsec processing.ipsec
can be followed by one or more request strings, which are formatted as below:- protocol
/
mode/
src-
dst [/level] - protocol is either
ah
,esp
, oripcomp
. mode is eithertransport
ortunnel
. src and dst specifies the IPsec endpoint. src always means the “sending node” and dst always means the “receiving node”. Therefore, when direction isin
, dst is this node and src is the other node (peer). If mode istransport
, Both src and dst can be omitted. level must be set to one of the following:default
,use
,require
, orunique
.default
means that the kernel should consult the system default policy defined by sysctl(8), such asnet.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 asrequire
, 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 afterunique
likeunique
: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 behavior. If level is omitted, it will be interpreted asdefault
.
entrust
andbypass
are not used. Refer to setkey(8) for details. 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
- protocol
RETURN VALUES¶
ipsec_set_policy() returns a pointer to the allocated buffer with the policy specification if successful; otherwise aNULL
pointer is returned.
ipsec_get_policylen() returns a positive value (meaning the
buffer size) on success, and a negative value on errors.
ipsec_dump_policy() returns a pointer to a dynamically
allocated region on success, and NULL
on errors.
SEE ALSO¶
ipsec_strerror(3), ipsec(4), setkey(8)HISTORY¶
The functions first appeared in the WIDE/KAME IPv6 protocol stack kit.May 5, 1998 | Debian |