setkey(8) -- Linux man page

 

NAME

setkey - manually manipulate the IPsec SA/SP database  

SYNOPSIS

setkey [-vrk ] file ...
setkey [-vrk ] -c
setkey [-vrk ] -f filename
setkey [-aPlvrk ] -D
setkey [-Pv -F ]
setkey [-H ] -x
setkey [-h ] [-V ]  

DESCRIPTION

setkey adds, updates, dumps, or flushes Security Association Database (SAD) entries as well as Security Policy Database (SPD) entries in the kernel.

setkey takes a series of operations from the standard input Po if invoked with -c Pc or the file named filename Po if invoked with -f filename Pc .

(no flag)
Dump the SAD entries or SPD entries contained in the specified file
-D
Dump the SAD entries. If with -P the SPD entries are dumped.
-F
Flush the SAD entries. If with -P the SPD entries are flushed.
-a
setkey usually does not display dead SAD entries with -D If with -a the dead SAD entries will be displayed as well. A dead SAD entry means that it has been expired but remains in the system because it is referenced by some SPD entries.
-H
Add hexadecimal dump on -x mode.
-l
Loop forever with short output on -D
-v
Be verbose. The program will dump messages exchanged on PF_KEY socket, including messages sent from other processes to the kernel.
-r
Use semantics described in IPSec RFCs. This mode is default. For details see section RFCvsLinuxkernelsemantics. Available only in Linux.
-k
Use semantics used in kernel. Available only in Linux.
-x
Loop forever and dump all the messages transmitted to PF_KEY socket. -xx makes each timestamps unformatted.
-h
Print short help.
-V
Print version string.

 

Configuration syntax

With -c or -f on the command line, setkey accepts the following configuration syntax. Lines starting with hash signs ('#') are treated as comment lines.

add [-46n ] src dst protocol spi [extensions ] algorithm ... ;
Add an SAD entry. add can fail with multiple reasons, including when the key length does not match the specified algorithm.
get [-46n ] src dst protocol spi ;
Show an SAD entry.
delete [-46n ] src dst protocol spi ;
Remove an SAD entry.
deleteall [-46n ] src dst protocol ;
Remove all SAD entries that match the specification.
flush [protocol ] ;
Clear all SAD entries matched by the options. -F on the command line achieves the same functionality.
dump [protocol ] ;
Dumps all SAD entries matched by the options. -D on the command line achieves the same functionality.
spdadd [-46n ] src_range dst_range upperspec policy ;
Add an SPD entry.
spdadd tagged tag policy ;
Add an SPD entry based on PF tag. tag must be a string surrounded by doublequote.
spddelete [-46n ] src_range dst_range upperspec -P direction ;
Delete an SPD entry.
spdflush ;
Clear all SPD entries. -FP on the command line achieves the same functionality.
spddump ;
Dumps all SPD entries. -DP on the command line achieves the same functionality.

Meta-arguments are as follows:

src
dst
Source/destination of the secure communication is specified as IPv4/v6 address. setkey can resolve a FQDN into numeric addresses. If the FQDN resolves into multiple addresses, setkey will install multiple SAD/SPD entries into the kernel by trying all possible combinations. -4 -6 and -n restricts the address resolution of FQDN in certain ways. -4 and -6 restrict results into IPv4/v6 addresses only, respectively. -n avoids FQDN resolution and requires addresses to be numeric addresses.

protocol
protocol is one of following:

esp
ESP based on rfc2406
esp-old
ESP based on rfc1827
ah
AH based on rfc2402
ah-old
AH based on rfc1826
ipcomp
IPComp

spi
Security Parameter Index (SPI) for the SAD and the SPD. spi must be a decimal number, or a hexadecimal number with ``0x '' prefix. SPI values between 0 and 255 are reserved for future use by IANA and they cannot be used.

extensions
take some of the following:

-m mode
Specify a security protocol mode for use. mode is one of following: transport , tunnel or any The default value is any
-r size
Specify window size of bytes for replay prevention. size must be decimal number in 32-bit word. If size is zero or not specified, replay check don't take place.
-u id
Specify the identifier of the policy entry in SPD. See policy
-f pad_option
defines the content of the ESP padding. pad_option is one of following:

zero-pad
All of the padding are zero.
random-pad
A series of randomized values are set.
seq-pad
A series of sequential increasing numbers started from 1 are set.

-f nocyclic-seq
Don't allow cyclic sequence number.
-lh time
-ls time
Specify hard/soft life time duration of the SA measured in seconds.
-bh bytes
-bs bytes
Specify hard/soft life time duration of the SA measured in bytes transported.

algorithm

-E ealgo key
Specify a encryption algorithm ealgo for ESP.
-E ealgo key -A aalgo key
Specify a encryption algorithm ealgo as well as a payload authentication algorithm aalgo for ESP.
-A aalgo key
Specify an authentication algorithm for AH.
-C calgo [-R ]
Specify a compression algorithm for IPComp. If -R is specified, spi field value will be used as the IPComp CPI (compression parameter index) on wire as is. If -R is not specified, the kernel will use well-known CPI on wire, and spi field will be used only as an index for kernel internal usage.

key must be double-quoted character string, or a series of hexadecimal digits preceded by ``0x ''

Possible values for ealgo aalgo and calgo are specified in separate section.

src_range
dst_range
These are selections of the secure communication specified as IPv4/v6 address or IPv4/v6 address range, and it may accompany TCP/UDP port specification. This takes the following form:
address
address/prefixlen
address[port]
address/prefixlen[port]

prefixlen and port must be decimal number. The square bracket around port is really necessary. They are not manpage metacharacters. For FQDN resolution, the rules applicable to src and dst apply here as well.

upperspec
Upper-layer protocol to be used. You can use one of words in /etc/protocols as upperspec Or icmp6 ip4 and any can be specified. any stands for ``any protocol'' Also you can use the protocol number. You can specify a type and/or a code of ICMPv6 when Upper-layer protocol is ICMPv6. the specification can be placed after icmp6 A type is separated with a code by single comma. A code must be specified anytime. When a zero is specified, the kernel deals with it as a wildcard. Note that the kernel can not distinguish a wildcard from that a type of ICMPv6 is zero. For example, the following means the policy doesn't require IPsec for any inbound Neighbor Solicitation.
spdadd ::/0 ::/0 icmp6 135,0 -P in none

NOTE: upperspec does not work against forwarding case at this moment, as it requires extra reassembly at forwarding node (not implemented at this moment) We have many protocols in /etc/protocols but protocols except of TCP, UDP and ICMP may not be suitable to use with IPsec. You have to consider and be careful to use them.

policy
policy is the one of the following three formats:
-P direction discard
-P direction none
-P direction ipsec protocol/mode/src-dst/level [...]

You must specify the direction of its policy as direction Either out , in or fwd are used. discard means the packet matching indexes will be discarded. none means that IPsec operation will not take place onto the packet. ipsec means that IPsec operation will take place onto the packet. The part of protocol/mode/src-dst/level specifies the rule how to process the packet. Either ah esp or ipcomp is to be set as protocol mode is either transport or tunnel If mode is tunnel you must specify the end-points addresses of the SA as src and dst with `-' between these addresses which is used to specify the SA to use. If mode is transport both src and dst can be omitted. level is to be one of the following: default , use , require or unique If the SA is not available in every level, the kernel will request getting SA to the key exchange daemon. default means the kernel consults to the system wide default against protocol you specified, e.g. esp_trans_deflev sysctl variable, when the kernel processes the packet. use means that the kernel use a SA if it's available, otherwise the kernel keeps normal operation. require means SA is required whenever the kernel sends a packet matched with the policy. unique is the same to require, in addition, it allows the policy to bind with the unique out-bound SA. You just specify the policy level unique racoon(8) will configure the SA for the policy. If you configure the SA by manual keying for that policy, you can put the decimal number as the policy identifier after unique separated by colon `:' like the following; unique:number in order to bind this policy to the SA. number must be between 1 and 32767. It corresponds to extensions -u of the manual SA configuration. When you want to use SA bundle, you can define multiple rules. For example, if an IP header was followed by AH header followed by ESP header followed by an upper layer protocol header, the rule would be:
esp/transport//require ah/transport//require
The rule order is very important.

Note that ``discard '' and ``none '' are not in the syntax described in ipsec_set_policy3. There are little differences in the syntax. See ipsec_set_policy3 for detail.

 

Algorithms

The following list shows the supported algorithms. protocol and algorithm are almost orthogonal. Followings are the list of authentication algorithms that can be used as aalgo in -A aalgo of protocol parameter:

algorithm       keylen (bits)
hmac-md5        128             ah: rfc2403
                128             ah-old: rfc2085
hmac-sha1       160             ah: rfc2404
                160             ah-old: 128bit ICV (no document)
keyed-md5       128             ah: 96bit ICV (no document)
                128             ah-old: rfc1828
keyed-sha1      160             ah: 96bit ICV (no document)
                160             ah-old: 128bit ICV (no document)
null            0 to 2048       for debugging
hmac-sha2-256   256             ah: 96bit ICV
                                (draft-ietf-ipsec-ciph-sha-256-00)
                256             ah-old: 128bit ICV (no document)
hmac-sha2-384   384             ah: 96bit ICV (no document)
                384             ah-old: 128bit ICV (no document)
hmac-sha2-512   512             ah: 96bit ICV (no document)
                512             ah-old: 128bit ICV (no document)
hmac-ripemd160  160             ah: 96bit ICV (RFC2857)
                                ah-old: 128bit ICV (no document)
aes-xcbc-mac    128             ah: 96bit ICV (RFC3566)
                128             ah-old: 128bit ICV (no document)

Followings are the list of encryption algorithms that can be used as ealgo in -E ealgo of protocol parameter:

algorithm       keylen (bits)
des-cbc         64              esp-old: rfc1829, esp: rfc2405
3des-cbc        192             rfc2451
null            0 to 2048       rfc2410
blowfish-cbc    40 to 448       rfc2451
cast128-cbc     40 to 128       rfc2451
des-deriv       64              ipsec-ciph-des-derived-01
3des-deriv      192             no document
rijndael-cbc    128/192/256     rfc3602
twofish-cbc     0 to 256        draft-ietf-ipsec-ciph-aes-cbc-01
aes-ctr         160/224/288     draft-ietf-ipsec-ciph-aes-ctr-03

Note that the first 128 bits of a key for aes-ctr will be used as AES key, and remaining 32 bits will be used as nonce.

Followings are the list of compression algorithms that can be used as calgo in -C calgo of protocol parameter:

algorithm
deflate         rfc2394
 

RFC vs Linux kernel semantics

Linux kernel uses fwd policy instead of in policy for packets what are forwarded through that particular box.

In kernel mode setkey manages and shows policies and SAs exactly as they are stored in the kernel.

In RFC mode setkey

creates fwd policies for every in policy inserted.
(not implemented yet) filters out all fwd policies
 

RETURN VALUES

The command exits with 0 on success, and non-zero on errors.  

EXAMPLES

add 3ffe:501:4819::1 3ffe:501:481d::1 esp 123457
        -E des-cbc 0x3ffe05014819ffff ;

add -6 myhost.example.com yourhost.example.com ah 123456
        -A hmac-sha1 "AH SA configuration!" ;

add 10.0.11.41 10.0.11.33 esp 0x10001
        -E des-cbc 0x3ffe05014819ffff
        -A hmac-md5 "authentication!!" ;

get 3ffe:501:4819::1 3ffe:501:481d::1 ah 123456 ;

flush ;

dump esp ;

spdadd 10.0.11.41/32[21] 10.0.11.33/32[any] any
        -P out ipsec esp/tunnel/192.168.0.1-192.168.1.2/require ;

 

SEE ALSO

ipsec_set_policy3, racoon(8), sysctl(8)
"Changed manual key configuration for IPsec" "http://www.kame.net/newsletter/19991007/" "October 1999"
 

HISTORY

The setkey command first appeared in WIDE Hydrangea IPv6 protocol stack kit. The command was completely re-designed in June 1998.  

BUGS

setkey should report and handle syntax errors better.

For IPsec gateway configuration, src_range and dst_range with TCP/UDP port number do not work, as the gateway does not reassemble packets (cannot inspect upper-layer headers)