Monitoring and Modifying Transport Layer Services

The transport layer protocols TCP, SCTP, and UDP are part of the standard Oracle Solaris package. These protocols typically need no intervention to run properly. However, circumstances at your site might require you to log or modify services that run over the transport layer protocols. Then, you must modify the profiles for these services by using the Service Management Facility (SMF), which is described in Chapter 6, Managing Services (Overview), in Oracle Solaris Administration: Common Tasks.

The inetd daemon is responsible for starting standard Internet services when a system boots. These services include applications that use TCP, SCTP, or UDP as their transport layer protocol. You can modify existing Internet services or add new services using the SMF commands. For more information about inetd, refer to inetd Internet Services Daemon.

Operations that involve the transport layer protocols include:

• Logging of all incoming TCP connections

• Adding services that run over a transport layer protocol, using SCTP as an example

• Configuring the TCP wrappers facility for access control

For detailed information on the inetd daemon refer to the inetd(1M)man page.

How to Log the IP Addresses of All Incoming TCP Connections

1. Become an administrator.

   For more information, see How to Obtain Administrative Rights in Oracle Solaris Administration: Security Services.

2. Set TCP tracing to enabled for all services managed by inetd.

   # inetadm -M tcp_trace=TRUE

How to Add Services That Use the SCTP Protocol

The SCTP transport protocol provides services to application layer protocols in a fashion similar to TCP. However, SCTP enables communication between two systems, either or both of which can be multihomed. The SCTP connection is called an association. In an association, an application divides the data to be transmitted into one or more message streams, or multi-streamed. An SCTP connection can go to endpoints with multiple IP addresses, which is particularly important for telephony applications. The multihoming capabilities of SCTP are a security consideration if your site uses IP Filter or IPsec. Some of these considerations are described in the sctp(7P) man page.

By default, SCTP is included in the Oracle Solaris and does not require additional configuration. However, you might need to explicitly configure certain application layer services to use SCTP. Some example applications are echo and discard. The next procedure shows how to add an echo service that uses an SCTP one-to-one style socket.

The following task shows how to add an SCTP inet service that is managed by the inetd daemon to the SMF repository. The task then shows how to use the Service Management Facility (SMF) commands to add the service.

• For information about SMF commands, refer to SMF Command-Line Administrative Utilities in Oracle Solaris Administration: Common Tasks.

• For syntactical information, refer to the man pages for the SMF commands, as cited in the procedure.

• For detailed information about SMF refer to the smf(5) man page.

Before You Begin

Before you perform the following procedure, create a manifest file for the service. The procedure uses as an example a manifest for the echo service that is called echo.sctp.xml.

1. Log in to the local system with a user account that has write privileges for system files.
2. Edit the /etc/services file and add a definition for the new service.

   Use the following syntax for the service definition.

   service-name |port/protocol | aliases

3. Add the new service.

   Go to the directory where the service manifest is stored and type the following:

   # cd dir-name
   # svccfg import service-manifest-name

   For a complete syntax of svccfg, refer to the svccfg(1M) man page.

   Suppose you want to add a new SCTP echo service using the manifest echo.sctp.xml that is currently located in the service.dir directory. You would type the following:

   # cd service.dir
   # svccfg import echo.sctp.xml

4. Verify that the service manifest has been added:

   # svcs FMRI

   For the FMRI argument, use the Fault Managed Resource Identifier (FMRI) of the service manifest. For example, for the SCTP echo service, you would use the following command:

   # svcs svc:/network/echo:sctp_stream

   Your output should resemble the following:

       STATE          STIME    FMRI
   disabled       16:17:00 svc:/network/echo:sctp_stream

   For detailed information about the svcs command, refer to the svcs(1) man page.

   The output indicates that the new service manifest is currently disabled.

5. List the properties of the service to determine if you must make modifications.

   # inetadm -l FMRI

   For detailed information about the inetadm command, refer to the inetadm(1M) man page.

   For example, for the SCTP echo service, you would type the following:

   # inetadm -l svc:/network/echo:sctp_stream
   SCOPE    NAME=VALUE
                name="echo"
                endpoint_type="stream"
                proto="sctp"
                isrpc=FALSE
                wait=FALSE
                exec="/usr/lib/inet/in.echod -s"
            .
            .
            default  tcp_trace=FALSE
              default  tcp_wrappers=FALSE

6. Enable the new service:

   # inetadm -e FMRI

7. Verify that the service is enabled:

   For example, for the new echo service, you would type the following:

   # inetadm | grep sctp_stream
   .
   .
       enabled   online         svc:/network/echo:sctp_stream

Example 3-9 Adding a Service That Uses the SCTP Transport Protocol

The following example shows the commands to use and the file entries required to have the echo service use the SCTP transport layer protocol.

$ cat /etc/services
.
.
echo            7/tcp
echo            7/udp
echo 7/sctp

# cd service.dir

    # svccfg import echo.sctp.xml

# svcs network/echo*
    STATE          STIME    FMRI
    disabled       15:46:44 svc:/network/echo:dgram
    disabled       15:46:44 svc:/network/echo:stream
    disabled       16:17:00 svc:/network/echo:sctp_stream

# inetadm -l svc:/network/echo:sctp_stream
    SCOPE    NAME=VALUE
             name="echo"
             endpoint_type="stream"
             proto="sctp"
             isrpc=FALSE
             wait=FALSE
             exec="/usr/lib/inet/in.echod -s"
             user="root"
    default  bind_addr=""
    default  bind_fail_max=-1
    default  bind_fail_interval=-1
    default  max_con_rate=-1
    default  max_copies=-1
    default  con_rate_offline=-1
    default  failrate_cnt=40
    default  failrate_interval=60
    default  inherit_env=TRUE
    default  tcp_trace=FALSE
    default  tcp_wrappers=FALSE

# inetadm -e svc:/network/echo:sctp_stream

# inetadm | grep echo
    disabled  disabled       svc:/network/echo:stream
    disabled  disabled       svc:/network/echo:dgram
    enabled   online         svc:/network/echo:sctp_stream

How to Use TCP Wrappers to Control Access to TCP Services

The tcpd program implements TCP wrappers. TCP wrappers add a measure of security for service daemons such as ftpd by standing between the daemon and incoming service requests. TCP wrappers log successful and unsuccessful connection attempts. Additionally, TCP wrappers can provide access control, allowing or denying the connection depending on where the request originates. You can use TCP wrappers to protect daemons such as SSH, Telnet, and FTP. The sendmail application can also use TCP wrappers, as described in Support for TCP Wrappers From Version 8.12 of sendmail in Oracle Solaris Administration: Network Services.

1. Become an administrator.

   For more information, see How to Obtain Administrative Rights in Oracle Solaris Administration: Security Services.

2. Set TCP wrappers to enabled.

   # inetadm -M tcp_wrappers=TRUE

3. Configure the TCP wrappers access control policy as described in the hosts_access(3) man page.

   This man page can be found in the /usr/sfw/man directory.