How to Add a New Preshared Key (IPsec and IKE Administration Guide)

IPsec and IKE Administration Guide

How to Add a New Preshared Key

You must have one preshared key for every policy entry in the ipsecinit.conf file. If you add a new policy entry while IPsec and IKE are running, the in.iked daemon can read in new keys. This procedure assumes the following:

The systems are named enigma and ada. Substitute your system names for these names.
The in.iked daemon is running on both systems.
The interface that you want to protect with IPsec is included as an entry in the /etc/hosts file on both systems. The following entry is an example.
192.168.15.7 ada
This procedure also works with an IPv6 address in the /etc/inet/ipnodes file.
You have added a new policy entry to the /etc/inet/ipsecinit.conf file on both systems. For example, the new entry on the enigma system appears similar to the following:
{laddr enigma raddr ada} ipsec {auth_algs any encr_algs any sa shared}
The entry on the ada system appears similar to the following:
{laddr ada raddr enigma} ipsec {auth_algs any encr_algs any sa shared}

You have created a rule for the enigma and ada systems to communicate securely in the /etc/inet/ike/config file on both systems. For example, the rule on the enigma system appears similar to the following:

### ike/config file on enigma, 192.168.116.16
…
## The rule to communicate with ada

{ label "enigma-to-ada"
  local_addr 192.168.116.16
  remote_addr 192.168.15.7
  p1_xform
  { auth_method preshared oakley_group 5 auth_alg md5 encr_alg blowfish }
  p2_pfs 5
	}

The rule on the ada system appears similar to the following:

### ike/config file on ada, 192.168.15.7
…
## The rule to communicate with enigma

{ label "ada-to-enigma"
  local_addr 192.168.15.7
  remote_addr 192.168.116.16
  p1_xform
  { auth_method preshared oakley_group 5 auth_alg md5 encr_alg blowfish }
  p2_pfs 5
}

On the system console, become superuser or assume an equivalent role.

Note –
Logging in remotely exposes security-critical traffic to eavesdropping. Even if you somehow protect the remote login, the security of the system is reduced to the security of the remote login session.

Check that the in.iked daemon permits you to change keying material.
# /usr/sbin/ikeadm get priv Current privilege level is 0x0, base privileges enabled
You can change keying material if the command returns a privilege level of 0x1 or 0x2. Level 0x0 does not permit keying material operations. By default, the in.iked daemon runs at the 0x0 level of privilege.

If the in.iked daemon does not permit you to change keying material, kill the daemon. Then, restart the daemon with the correct privilege level.
# pkill in.iked # /usr/lib/inet/in.iked -p 2 Setting privilege level to 2!

Generate random numbers and construct a key of 64 to 448 bits.

For details, see How to Generate Random Numbers.

By some means, send the key to the administrator of the remote system.

You both need to add the same preshared key at the same time.

Add the new keying material with the add preshared subcommand in ikeadm command mode.

ikeadm> add preshared { localidtype id-type localid id
remoteidtype id-type remoteid id ike_mode mode key key }

id-type: Specifies the type of the id.
id: Specifies the IP address when id-type is IP.
mode: Specifies the IKE mode. The only accepted value is main.
key: Specifies the preshared key in hexadecimal format.

For example, on host enigma, you would add the key for the new interface, ada.

# ikeadm
ikeadm> add preshared { localidtype ip localid 192.168.116.16
remoteidtype ip remoteid 192.168.15.7 ike_mode main
key 8d1fb4ee500e2bea071deb2e781cb48374411af5a9671714672bb1749ad9364d }
ikeadm: Successfully created new preshared key.

On host ada, you would add the identical key.

# ikeadm
ikeadm> add preshared { localidtype ip localid 192.168.15.7
remoteidtype ip remoteid 192.168.116.16 ike_mode main
key 8d1fb4ee500e2bea071deb2e781cb48374411af5a9671714672bb1749ad9364d }
ikeadm: Successfully created new preshared key.

Exit the ikeadm command mode.
ikeadm> exit #

On each system, lower the privilege level of the in.iked daemon.
# ikeadm set priv base

On each system, activate the ipsecinit.conf file to secure the added interface.
# ipsecconf -a /etc/inet/ipsecinit.conf
Caution –
Read the warning when you execute the ipsecconf command. The same warning applies to restarting the in.iked daemon. A socket that is already latched, that is, the socket is in use, provides an unsecured back door into the system. For more extensive discussion, see Security Considerations for ipsecinit.conf and ipsecconf.

On each system, read in the new rules by using the ikeadm command.
# ikeadm read rules
A sample of the new rules for the ada and enigma systems is available at the start of the procedure. Because the rules are in the /etc/inet/ike/config file, the name of the file does not have to be specified to the ikeadm command.

To ensure that IKE preshared keys are available at reboot, add the keys to the /etc/inet/secret/ike.preshared file.

For example, on the enigma system, you would add the following keying information to the ike.preshared file:

# ike.preshared on enigma for the ada interface
#…
{ localidtype IP
  localid 192.168.116.16
  remoteidtype IP
  remoteid 192.168.15.7
  # enigma and ada's shared key in hex (32 - 448 bits required)
  key 8d1fb4ee500e2bea071deb2e781cb48374411af5a9671714672bb1749ad9364d
}

On the ada system, you would add the following keying information to the ike.preshared file:

# ike.preshared on ada for the enigma interface
#…
{ localidtype IP
  localid 192.168.15.7
  remoteidtype IP
  remoteid 192.168.116.16
  # ada and enigma's shared key in hex (32 - 448 bits required)
  key 8d1fb4ee500e2bea071deb2e781cb48374411af5a9671714672bb1749ad9364d
}

Verify that the systems can communicate. See How to Verify That the Preshared Keys Are Identical.