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IPSEC_SET_POLICY(3)     System Library Functions Manual    IPSEC_SET_POLICY(3)

NAME

     ipsec_set_policy, ipsec_get_policylen, ipsec_dump_policy - manipulate

     IPsec policy specification structure from readable string

LIBRARY

     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 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.  The buffer is dynam-

     ically 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).  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/10.1.1.2-10.1.1.1/use

           in ipsec ipcomp/transport//use

                   esp/transport//use

RETURN VALUES

     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

     errors.

SEE ALSO

     ipsec_strerror(3), ipsec(4), setkey(8)

HISTORY

     The functions first appeared in WIDE/KAME IPv6 protocol stack kit.

KAME                              May 5, 1998                             KAME

IPSEC_STRERROR(3)       System Library Functions Manual      IPSEC_STRERROR(3)

NAME

     ipsec_strerror - error message for IPsec policy manipulation library

SYNOPSIS

     #include <netinet6/ipsec.h>

     const char *

     ipsec_strerror();

DESCRIPTION

     netinet6/ipsec.h declares

           extern int ipsec_errcode;

     which is used to pass an error code from IPsec policy manipulation

     library to an user program.  ipsec_strerror() can be used to obtain the

     error message string for the error code.

     The array pointed to is not to be modified by the program.  Since

     ipsec_strerror() uses strerror(3) as underlying function, calling

     strerror(3) after ipsec_strerror() would make the return value from

     ipsec_strerror() invalid, or overwritten.

RETURN VALUES

     ipsec_strerror() always return a pointer to C string.  The C string must

     not be overwritten by user programs.

SEE ALSO

     ipsec_set_policy(3)

HISTORY

     ipsec_strerror() first appeared in WIDE/KAME IPv6 protocol stack kit.

BUGS

     ipsec_strerror() will return its result which may be overwritten by sub-

     sequent calls.

     ipsec_errcode is not thread safe.

KAME                              May 6, 1998                             KAME