Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
IPSEC_SET_POLICY(3)    FreeBSD Library Functions Manual	   IPSEC_SET_POLICY(3)

     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);

     ipsec_get_policylen(char *buf);

     char *
     ipsec_dump_policy(char *buf, char *delim);

     ipsec_set_policy()	generates IPsec	policy specification structure,	namely
     struct sadb_x_policy and/or struct	sadb_x_ipsecrequest from human-read-
     able policy specification.	 Policy	specification must be given as C
     string policy and length len of policy.  ipsec_set_policy() will return
     the buffer	of IPsec policy	specification structure.

     You may want the length of	the generated buffer such when calling
     setsockopt(2).  ipsec_get_policylen() will	return the length.

     ipsec_dump_policy() converts IPsec	policy structure into readable form.
     Therefore,	ipsec_dump_policy() can	be regarded as inverse conversion of
     ipsec_set_policy().  buf points to	a 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.
     ipsec_dump_policy() returns 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 direc-
	      tion the policy needs to be applied.  With discard policy, pack-
	      ets 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 pro-
	      cessing.	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 omited.

		       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 transmit-
		       ted 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 out-
		       bound 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.  How-
		       ever, 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/
	   in ipsec ipcomp/transport//use

     ipsec_set_policy()	returns	a pointer to the allocated buffer of policy
     specification if successful; otherwise a NULL pointer is returned.
     ipsec_get_policylen() returns with	positive value (meaning	the buffer
     size) on success, and negative value on errors.  ipsec_dump_policy()
     returns a pointer to dynamically allocated	region on success, and NULL on

     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 (
     stack was initially integrated into FreeBSD 4.0

FreeBSD	11.1			  May 5, 1998			  FreeBSD 11.1


Want to link to this manual page? Use this URL:

home | help