.\" $KAME: ipsec_set_policy.3,v 1.15 2001/08/17 07:21:36 itojun Exp $ .\" .\" Copyright (C) 1995, 1996, 1997, 1998, and 1999 WIDE Project. .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. 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IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" $FreeBSD$ .\" .Dd February 14, 2006 .Dt IPSEC_SET_POLICY 3 .Os .Sh NAME .Nm ipsec_set_policy , .Nm ipsec_get_policylen , .Nm ipsec_dump_policy .Nd create an IPsec policy structure from a human readable string .\" .Sh LIBRARY .Lb libipsec .Sh SYNOPSIS .In netipsec/ipsec.h .Ft "char *" .Fn ipsec_set_policy "char *policy" "int len" .Ft int .Fn ipsec_get_policylen "char *buf" .Ft "char *" .Fn ipsec_dump_policy "char *buf" "char *delim" .Sh DESCRIPTION The .Fn ipsec_set_policy function generates an IPsec policy specification structure, .Li struct sadb_x_policy and/or .Li struct sadb_x_ipsecrequest from a human-readable policy specification. The policy specification must be given as a C string, passed in the .Fa policy argument and the length of the string, given as .Fa len . The .Fn ipsec_set_policy function returns pointer to a buffer which contains a properly formed IPsec policy specification structure. The buffer is dynamically allocated, and must be freed by using the .Xr free 3 library function. .Pp The .Fn ipsec_get_policylen function returns the length of the buffer which is needed when passing the specification structure to the .Xr setsockopt 2 system call. .Pp The .Fn ipsec_dump_policy function converts an IPsec policy structure into a human readable form. The .Fa buf argument points to an IPsec policy structure, .Li struct sadb_x_policy . .Fa delim is a delimiter string, which is usually a blank character. If you set .Fa delim to .Dv NULL , a single white space is assumed. The .Fn ipsec_dump_policy function returns a pointer to dynamically allocated string. It is the caller's responsibility to free the returned pointer using the .Xr free 3 library call. .Pp A .Fa policy is given in the following way: .Bl -tag -width "discard" .It Ar direction Li discard The .Ar direction must be .Li in or .Li out and specifies which direction the policy needs to be applied, either on inbound or outbound packets. When the .Li discard policy is selected, packets will be dropped if they match the policy. .It Ar direction Li entrust .Li entrust means to consult the security policy database (SPD) in the kernel, as controlled by .Xr setkey 8 . .It Ar direction Li bypass A direction of .Li bypass indicates that IPsec processing should not occur and that the packet will be transmitted in clear. The bypass option is only available to privileged sockets. .It Xo .Ar direction .Li ipsec .Ar request ... .Xc A direction of .Li ipsec means that matching packets are processed by IPsec. .Li ipsec can be followed by one or more .Ar request string, which is formatted as: .Bl -tag -width "discard" .It Xo .Ar protocol .Li / .Ar mode .Li / .Ar src .Li - .Ar dst .Op Ar /level .Xc The .Ar protocol is one of: .Li ah , .Li esp or .Li ipcomp indicating Authentication Header, Encapsulating Security Protocol or IP Compression protocol is used. .Pp The .Ar mode is either .Li transport or .Li tunnel the meanings of both modes are described in .Xr ipsec 4 . .Pp The .Ar src and .Ar dst specify the IP address, either v4 or v6, of the source and destination systems. The .Ar src always stands for the .Dq sending node and .Ar dst always stands for the .Dq receiving node . When .Ar direction is .Li in , .Ar dst is this local node and .Ar src is the remote node or peer. If .Ar mode is .Li transport , both .Ar src and .Ar dst can be omitted. .Pp The .Ar level must be set to one of the following: .Li default , use , require or .Li unique . .Li default means that the kernel should consult the default security policies as defined by a set of .Xr sysctl 8 , variables. The relevant .Xr sysctl 8 variables are described in .Xr ipsec 4 . .Pp When .Li use is selected a relevant security association (SA) can be used when available but is not necessary. If the SA is available then packets will be handled by IPsec, i.e., encrypted and/or authenticated but if an SA is not available then packets will be transmitted in the clear. The .Li use option is not recommended because it allows for accidental mis-configurations where encrypted or authenticated link becomes unencrypted or unauthenticated, the .Li require keyword is recommended instead of .Li use where possible. Using the .Li require keyword means that a relevant SA is required, and that the kernel must perform IPsec processing on all matching packets. .Pp The .Li unique keyword has the same effect as .Li 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 using .Xr setkey 8 . Put the decimal number as the identifier after the .Li unique keyword in this way: .Li unique : number , where .Li number must be between 1 and 32767. .Pp If the .Ar request string is kept unambiguous, .Ar level and the slash prior to .Ar level can be omitted but you are encouraged to specify them explicitly to avoid unintended behaviors. If .Ar level is omitted, it will be interpreted as .Li default . .El .El .Pp Note that there is a difference between the specification allowed here and in .Xr setkey 8 . When specifying security policies with .Xr setkey 8 , neither entrust nor bypass are used. Refer to .Xr setkey 8 for details. .Sh RETURN VALUES The .Fn ipsec_set_policy function returns a pointer to the allocated buffer containing a the policy specification if successful; otherwise a NULL pointer is returned. .Pp The .Fn ipsec_get_policylen function returns a positive value, indicating the buffer size, on success, and a negative value on error. .Pp The .Fn ipsec_dump_policy function returns a pointer to a dynamically allocated region containing a human readable security policy on success, and .Dv NULL on error. .Sh EXAMPLES Set a policy that all inbound packets are discarded. .Pp .Dl "in discard" .Pp .\" All outbound packets are required to be processed by IPsec and transported using ESP. .Pp .Dl "out ipsec esp/transport//require" .Pp .\" All inbound packets are required to be authenticated using the AH protocol. .Pp .Dl "in ipsec ah/transport//require" .Pp .\" Tunnel packets outbound through the endpoints at 10.1.1.2 and 10.1.1.1. .Pp .Dl "out ipsec esp/tunnel/10.1.1.2-10.1.1.1/require" .Sh SEE ALSO .Xr ipsec_strerror 3 , .Xr ipsec 4 , .Xr setkey 8 .Sh HISTORY These functions first appeared in WIDE/KAME IPv6 protocol stack kit. .Pp IPv6 and IPsec support based on the KAME Project (http://www.kame.net/) stack was initially integrated into .Fx 4.0 .