IPsec Utilities and Files

This section describes the configuration file that initializes IPsec. This section also describes various commands that enable you to manage IPsec within your network. For instructions about how to implement IPsec within your network, see Implementing IPsec (Task Map).

IPsec Policy Command

You use the ipsecconf command to configure the IPsec policy for a host. When you run the command to configure the policy, the system creates a temporary file that is named ipsecpolicy.conf. This file holds the IPsec policy entries that were set in the kernel by the ipsecconf command. The system uses the in-kernel IPsec policy entries to check all outbound and inbound IP datagrams for policy. Forwarded datagrams are not subjected to policy checks that are added by using this command. For information on how to protect forwarded packets, see the ifconfig(1M) and tun(7M) man pages. For IPsec policy options, see the ipsecconf(1M) man page.

You must become superuser or assume an equivalent role to invoke the ipsecconf command. The command accepts entries that protect traffic in both directions, and entries that protect traffic in only one direction.

Policy entries with a format of local address and remote address can protect traffic in both directions with a single policy entry. For example, entries that contain the patterns laddr host1 and raddr host2, protect traffic in both directions if no direction is specified for the named host. Thus, you need only one policy entry for each host. Policy entries with a format of source address to destination address protect traffic in only one direction. For example, a policy entry of the pattern saddr host1 daddr host2 protects inbound traffic or outbound traffic, not both directions. Thus, to protect traffic in both directions, you need to pass the ipsecconf command another entry, as in saddr host2 daddr host1.

You can see the policies that are configured in the system when you issue the ipsecconf command without any arguments. The command displays each entry with an index followed by a number. You can use the -d option with the index to delete a particular policy in the system. The command displays the entries in the order that the entries were added, which is not necessarily the order in which the traffic match occurs. To view the order in which the traffic match occurs, use the -l option.

The ipsecpolicy.conf file is deleted when the system shuts down. To ensure that the IPsec policy is active when the machine boots, you can create an IPsec policy file, /etc/inet/ipsecinit.conf, that the inetinit script reads during startup.

IPsec Policy File

To invoke IPsec security policies when you start the Solaris operating environment, you create a configuration file to initialize IPsec with your specific IPsec policy entries. You should name the file /etc/inet/ipsecinit.conf. See the ipsecconf(1M) man page for details about policy entries and their format. After policies are configured, you can use the ipsecconf command to delete a policy temporarily, or to view the existing configuration.

Example—ipsecinit.conf File

The Solaris software includes an IPsec policy file as a sample. This sample file is named ipsecinit.sample. You can use the file as a template to create your own ipsecinit.conf file. The ipsecinit.sample file contains the following examples:

#
# For example,
#
#	 {rport 23} ipsec {encr_algs des encr_auth_algs md5}
#
# will protect the telnet traffic originating from the host with ESP using
# DES and MD5. Also:
#
#	 {raddr 10.5.5.0/24} ipsec {auth_algs any}
#
# will protect traffic to or from the 10.5.5.0 subnet with AH 
# using any available algorithm.
#
#
# To do basic filtering, a drop rule may be used. For example:
#
#    {lport 23 dir in} drop {}
#    {lport 23 dir out} drop {}
#
# will disallow any remote system from telnetting in.

Security Considerations for ipsecinit.conf and ipsecconf

If, for example, the /etc/inet/ipsecinit.conf file is sent from an NFS-mounted file system, an adversary can modify the data contained in the file. The outcome would be a change to the configured policy. Consequently, you should use extreme caution if transmitting a copy of the ipsecinit.conf file over a network.

The policy cannot be changed for TCP sockets or UDP sockets on which a connect() or accept() function call has been issued. A socket whose policy cannot be changed is called a latched socket. New policy entries do not protect sockets that are already latched. See the connect(3SOCKET) and accept(3SOCKET) man pages.

Ensure that you set up the policies before starting any communications, because existing connections might be affected by the addition of new policy entries. Similarly, do not change policies in the middle of a communication.

Protect your naming system. If the following two conditions are met, then your host names are no longer trustworthy:

• Your source address is a host that can be looked up over the network

• Your naming system is compromised

Security weaknesses often lie in misapplication of tools, not the actual tools. You should be cautious when using the ipsecconf command. Use a console or other hard-connected TTY for the safest mode of operation.

Security Associations Database for IPsec

Information on keying material for IPsec security services is maintained in a security association database (SADB). Security associations protect both inbound packets and outbound packets. A user process, or possibly multiple cooperating processes, maintains SADBs by sending messages over a special kind of socket. This method of maintaining SADBs is analogous to the method that is described in the route(7P) man page. Only a superuser or someone who has assumed an equivalent role can access an SADB.

The operating system might spontaneously emit messages in response to external events. For example, the system might request for a new SA for an outbound datagram, or the system might report the expiration of an existing SA. You open the channel for passing SADB control messages by using the socket call that is mentioned in the previous section. More than one key socket can be open per system.

Messages include a small base header, followed by a number of extension messages. The number of messages might be zero or more. Some messages require additional data. The base message and all extensions must be 8-byte aligned. The GET message serves as an example. This message requires the base header, the SA extension, and the ADDRESS_DST extension. See the pf_key(7P) man page for details.

Keying Utilities

The IKE protocol is the automatic keying utility for IPv4 and IPv6 addresses. See Chapter 4, Administering IKE (Tasks) for how to set up IKE. The manual keying utility is the ipseckey command. See the ipseckey(1M) man page.

You use the ipseckey command to manually manipulate the security association databases with the ipsecah and ipsecesp protection mechanisms. You can also use the ipseckey command to set up security associations between communicating parties when automated key management is not used.

While the ipseckey command has only a limited number of general options, the command supports a rich command language. You can specify that requests should be delivered by means of a programmatic interface specific for manual keying. See the pf_key(7P) man page for additional information. When you invoke the ipseckey command with no arguments, the command enters an interactive mode that displays a prompt that enables you to make entries. Some commands require an explicit security association (SA) type, while others permit you to specify the SA type and act on all SA types.

Security Considerations for ipseckey

The ipseckey command enables a privileged user to enter sensitive cryptographic keying information. If an adversary gains access to this information, the adversary can compromise the security of IPsec traffic. You should consider the following issues when you handle keying material and use the ipseckey command:

1. Have you refreshed the keying material? Periodic key refreshment is a fundamental security practice. Key refreshment guards against potential weaknesses of the algorithm and keys, and limits the damage of an exposed key.

2. Is the TTY going over a network? Is the ipseckey command in interactive mode?

   • In interactive mode, the security of the keying material is the security of the network path for this TTY's traffic. You should avoid using the ipseckey command over a clear-text telnet or rlogin session.

   • Even local windows might be vulnerable to attacks by a concealed program that reads window events.

3. Is the file being accessed over the network? Can the file be read by the world? Have you used the -f option?

   • An adversary can read a network-mounted file as the file is being read. You should avoid using a world-readable file that contains keying material.

   • Protect your naming system. If the following two conditions are met, then your host names are no longer trustworthy:

     • Your source address is a host that can be looked up over the network

     • Your naming system is compromised

Security weaknesses often lie in misapplication of tools, not the actual tools. You should be cautious when using the ipseckey command. Use a console or other hard-connected TTY for the safest mode of operation.

IPsec Extensions to Other Utilities

The ifconfig command has options to manage the IPsec policy on a tunnel interface. The snoop command can parse AH and ESP headers.

ifconfig Command

To support IPsec, the following security options have been added to the ifconfig command:

• auth_algs

• encr_auth_algs

• encr_algs

You must specify all IPsec security options for a tunnel in one invocation. For example, if you are using only ESP to protect traffic, you would configure the tunnel, ip.tun0, once with both security options, as in:

# ifconfig ip.tun0 … encr_algs 3DES encr_auth_algs MD5

Similarly, an ipsecinit.conf entry would configure the tunnel once with both security options, as in:

# WAN traffic uses ESP with 3DES and MD5.
   {} ipsec {encr_algs 3des encr_auth_algs md5}

auth_algs Security Option

This option enables IPsec AH for a tunnel with a specified authentication algorithm. The auth_algs option has the following format:

auth_algs authentication-algorithm

For the algorithm, you can specify either a number or an algorithm name, including the parameter any, to express no specific algorithm preference. To disable tunnel security, specify the following option:

auth_algs none

See Table 1–1 for a list of available authentication algorithms and for pointers to the algorithm man pages.

encr_auth_algs Security Option

This option enables IPsec ESP for a tunnel with a specified authentication algorithm. The encr_auth_algs option has the following format:

encr_auth_algs authentication-algorithm

For the algorithm, you can specify either a number or an algorithm name, including the parameter any, to express no specific algorithm preference. If you specify an ESP encryption algorithm, but you do not specify the authentication algorithm, the ESP authentication algorithm value defaults to the parameter any.

See Table 1–1 for a list of available authentication algorithms and for pointers to the algorithm man pages.

encr_algs Security Option

This option enables IPsec ESP for a tunnel with a specified encryption algorithm. The encr_algs option has the following format:

encr_algs encryption-algorithm

For the algorithm, you can specify either a number or an algorithm name. To disable tunnel security, specify the following option:

encr_algs none

If you specify an ESP authentication algorithm, but not an encryption algorithm, ESP's encryption value defaults to the parameter null.

For a list of available encryption algorithms and for pointers to the algorithm man pages, see the ipsecesp(7P) man page or Table 1–2.

snoop Command

The snoop command can now parse AH and ESP headers. Because ESP encrypts its data, the snoop command cannot see encrypted headers that are protected by ESP. AH does not encrypt data, so traffic can still be inspected with this command. The snoop -V option shows when AH is in use on a packet. See the snoop(1M) man page for more details.

For a sample of verbose snoop output on a protected packet, see How to Verify That Packets Are Protected.