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System Administration Guide: IP Services

Chapter 20 IP Security Architecture (Reference)

This chapter contains the following reference information:

For instructions on how to implement IPsec on your network, see Chapter 19, Configuring IPsec (Tasks). For an overview of IPsec, see Chapter 18, IP Security Architecture (Overview).

IPsec Service Management Facility

The service management facility (SMF) provides the following services for IPsec:

For information about SMF, see Chapter 16, Managing Services (Overview), in System Administration Guide: Basic Administration. Also see the smf(5), svcadm(1M), and svccfg(1M) man pages.

ipsecconf 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 the IPsec policy entries in the kernel. The system uses these entries to check the policy on all inbound and outbound IP datagrams. Forwarded datagrams are not subjected to policy checks that are added by using this command. The ipsecconf command also configures the security policy database (SPD).

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

To ensure that the IPsec policy is active when the machine boots, you can create an IPsec policy file, /etc/inet/ipsecinit.conf. This file is read when the network services are started. For instructions on how to create an IPsec policy file, see Protecting Traffic With IPsec (Task Map).

With the -c option, the ipsecconf command checks the syntax of the IPsec policy file that you provide as an argument.

Policy entries that are added by the ipsecconf command are not persistent over a system reboot. To ensure that the IPsec policy is active when the system boots, add the policy entries to the /etc/inet/ipsecinit.conf file, then refresh or enable the policy service. For examples, see Protecting Traffic With IPsec (Task Map).

ipsecinit.conf File

To invoke IPsec security policies when you start the Solaris Operating System (Solaris OS), you create a configuration file to initialize IPsec with your specific IPsec policy entries. The default name for this file is /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 view the existing configuration.

Sample ipsecinit.conf File

The Solaris software includes a sample IPsec policy file, 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.
#
# If you are using IPv6, it may be useful to bypass neighbor discovery
# to allow in.iked to work properly with on-link neighbors. To do that,
# add the following lines:
#
#        {ulp ipv6-icmp type 133-137 dir both } pass { }
#
# This will allow neighbor discovery to work normally.

Security Considerations for ipsecinit.conf and ipsecconf

Use extreme caution if transmitting a copy of the ipsecinit.conf file over a network. An adversary can read a network-mounted file as the file is being read. If, for example, the /etc/inet/ipsecinit.conf file is accessed or is copied from an NFS-mounted file system, an adversary can change the policy that is contained in the file.

Ensure that you set up IPsec 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.

Specifically, IPsec policy cannot be changed for SCTP, TCP, 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. For more information, see the connect(3SOCKET) and accept(3SOCKET) man pages.

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

Security weaknesses often arise from the misapplication of tools, not from 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.

ipsecalgs Command

The Solaris cryptographic framework provides authentication and encryption algorithms to IPsec. The ipsecalgs command can list the algorithms that each IPsec protocol supports. The ipsecalgs configuration is stored in the /etc/inet/ipsecalgs file. Typically, this file does not need to be modified. However, if the file needs to be modified, use the ipsecalgs command. The file must never be edited directly. The supported algorithms are synchronized with the kernel at system boot by the svc:/network/ipsec/ipsecalgs:default service.

The valid IPsec protocols and algorithms are described by the ISAKMP domain of interpretation (DOI), which is covered by RFC 2407. In a general sense, a DOI defines data formats, network traffic exchange types, and conventions for naming security-relevant information. Security policies, cryptographic algorithms, and cryptographic modes are examples of security-relevant information.

Specifically, the ISAKMP DOI defines the naming and numbering conventions for the valid IPsec algorithms and for their protocols, PROTO_IPSEC_AH and PROTO_IPSEC_ESP. Each algorithm is associated with exactly one protocol. These ISAKMP DOI definitions are in the /etc/inet/ipsecalgs file. The algorithm and protocol numbers are defined by the Internet Assigned Numbers Authority (IANA). The ipsecalgs command makes the list of algorithms for IPsec extensible.

For more information about the algorithms, refer to the ipsecalgs(1M) man page. For more information on the Solaris cryptographic framework, see Chapter 13, Solaris Cryptographic Framework (Overview), in System Administration Guide: Security Services.

Security Associations Database for IPsec

Information on key material for IPsec security services is maintained in a security associations database (SADB). Security associations (SAs) protect inbound packets and outbound packets. The SADBs are maintained by a user process, or possibly multiple cooperating processes, that send 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 superuser or a user who has assumed an equivalent role can access the database.

The in.iked daemon and the ipseckey command use the PF_KEY socket interface to maintain SADBs. For more information on how SADBs handle requests and messages, see the pf_key(7P) man page.

Utilities for Key Generation in IPsec

The IKE protocol provides automatic key management for IPv4 and IPv6 addresses. See Chapter 22, Configuring IKE (Tasks) for instructions on how to set up IKE. The manual keying utility is the ipseckey command, which is described in the ipseckey(1M) man page.

You use the ipseckey command to manually populate the security associations database (SADB). Typically, manual SA generation is used when IKE is unavailable for some reason. However, if the SPI values are unique, manual SA generation and IKE can be used at the same time.

The ipseckey command can be used to view all SAs that are known to the system, whether the keys were added manually or by IKE. With the -c option, the ipseckey command checks the syntax of the keys file that you provide as an argument.

IPsec SAs that are added by the ipseckey command are not persistent over system reboot. To enable manually added SAs at system boot, add entries to the /etc/inet/secret/ipseckeys file, then enable the svc:/network/ipsec/manual-key:default service. For the procedure, see How to Manually Create IPsec Security Associations.

While the ipseckey command has only a limited number of general options, the command supports a rich command language. You can specify that requests be delivered by means of a programmatic interface specific for manual keying. For additional information, see the pf_key(7P) man page.

Security Considerations for ipseckey

The ipseckey command enables superuser or a role with the Network Security or Network IPsec Management rights profile 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:

Security weaknesses often arise from the misapplication of tools, not from 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.

snoop Command and IPsec

The snoop command can 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. Therefore, traffic that is protected by AH can be inspected with the snoop command. The -V option to the command shows when AH is in use on a packet. For more details, see the snoop(1M) man page.

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