Chapter 32. Network Servers

Configuration of inetd is done by editing /etc/inetd.conf. Each line of this configuration file represents an application which can be started by inetd. By default, every line starts with a comment (#), meaning that inetd is not listening for any applications. To configure inetd to listen for an application’s connections, remove the # at the beginning of the line for that application.

After saving your edits, configure inetd to start at system boot by editing /etc/rc.conf:

To start inetd now, so that it listens for the service you configured, type:

Once inetd is started, it needs to be notified whenever a modification is made to /etc/inetd.conf:

Typically, the default entry for an application does not need to be edited beyond removing the #. In some situations, it may be appropriate to edit the default entry.

As an example, this is the default entry for ftpd(8) over IPv4:

The seven columns in an entry are as follows:

where:

Like most server daemons, inetd has a number of options that can be used to modify its behavior. By default, inetd is started with -wW -C 60. These options enable TCP wrappers for all services, including internal services, and prevent any IP address from requesting any service more than 60 times per minute.

To change the default options which are passed to inetd, add an entry for inetd_flags in /etc/rc.conf. If inetd is already running, restart it with service inetd restart.

The available rate limiting options are:

Additional options are available. Refer to inetd(8) for the full list of options.

Many of the daemons which can be managed by inetd are not security-conscious. Some daemons, such as fingerd, can provide information that may be useful to an attacker. Only enable the services which are needed and monitor the system for excessive connection attempts. max-connections-per-ip-per-minute, max-child and max-child-per-ip can be used to limit such attacks.

By default, TCP wrappers are enabled. Consult hosts_access(5) for more information on placing TCP restrictions on various inetd invoked daemons.

The file systems which the NFS server will share are specified in /etc/exports. Each line in this file specifies a file system to be exported, which clients have access to that file system, and any access options. When adding entries to this file, each exported file system, its properties, and allowed hosts must occur on a single line. If no clients are listed in the entry, then any client on the network can mount that file system.

The following /etc/exports entries demonstrate how to export file systems. The examples can be modified to match the file systems and client names on the reader’s network. There are many options that can be used in this file, but only a few will be mentioned here. See exports(5) for the full list of options.

This example shows how to export /cdrom to three hosts named alpha, bravo, and charlie:

The -ro flag makes the file system read-only, preventing clients from making any changes to the exported file system. This example assumes that the host names are either in DNS or in /etc/hosts. Refer to hosts(5) if the network does not have a DNS server.

The next example exports /home to three clients by IP address. This can be useful for networks without DNS or /etc/hosts entries. The -alldirs flag allows subdirectories to be mount points. In other words, it will not automatically mount the subdirectories, but will permit the client to mount the directories that are required as needed.

This next example exports /a so that two clients from different domains may access that file system. The -maproot=root allows root on the remote system to write data on the exported file system as root. If -maproot=root is not specified, the client’s root user will be mapped to the server’s nobody account and will be subject to the access limitations defined for nobody.

A client can only be specified once per file system. For example, if /usr is a single file system, these entries would be invalid as both entries specify the same host:

The correct format for this situation is to use one entry:

The following is an example of a valid export list, where /usr and /exports are local file systems:

To enable the processes required by the NFS server at boot time, add these options to /etc/rc.conf:

The server can be started now by running this command:

Whenever the NFS server is started, mountd also starts automatically. However, mountd only reads /etc/exports when it is started. To make subsequent /etc/exports edits take effect immediately, force mountd to reread it:

Refer to zfs-share(8) for a description of exporting ZFS datasets via NFS using the sharenfs ZFS property instead of the exports(5) file.

Refer to nfsv4(4) for a description of an NFS Version 4 setup.

To enable NFS clients, set this option in each client’s /etc/rc.conf:

Then, run this command on each NFS client:

The client now has everything it needs to mount a remote file system. In these examples, the server’s name is server and the client’s name is client. To mount /home on server to the /mnt mount point on client:

The files and directories in /home will now be available on client, in the /mnt directory.

To mount a remote file system each time the client boots, add it to /etc/fstab:

Refer to fstab(5) for a description of all available options.

Some applications require file locking to operate correctly. To enable locking, execute the following command on both the client and server:

Then start the rpc.lockd(8) service:

If locking is not required on the server, the NFS client can be configured to lock locally by including -L when running mount. Refer to mount_nfs(8) for further details.

The autofs(5) facility is a common name for several components that, together, allow for automatic mounting of remote and local filesystems whenever a file or directory within that file system is accessed. It consists of the kernel component, autofs(5), and several userspace applications: automount(8), automountd(8) and autounmountd(8). It serves as an alternative for amd(8) from previous FreeBSD releases. amd is still provided for backward compatibility purposes, as the two use different map formats; the one used by autofs is the same as with other SVR4 automounters, such as the ones in Solaris, MacOS X, and Linux.

The autofs(5) virtual filesystem is mounted on specified mountpoints by automount(8), usually invoked during boot.

Whenever a process attempts to access a file within the autofs(5) mountpoint, the kernel will notify automountd(8) daemon and pause the triggering process. The automountd(8) daemon will handle kernel requests by finding the proper map and mounting the filesystem according to it, then signal the kernel to release blocked process. The autounmountd(8) daemon automatically unmounts automounted filesystems after some time, unless they are still being used.

The primary autofs configuration file is /etc/auto_master. It assigns individual maps to top-level mounts. For an explanation of auto_master and the map syntax, refer to auto_master(5).

There is a special automounter map mounted on /net. When a file is accessed within this directory, autofs(5) looks up the corresponding remote mount and automatically mounts it. For instance, an attempt to access a file within /net/foobar/usr would tell automountd(8) to mount the /usr export from the host foobar.

The output from showmount shows /usr as an export. When changing directories to /host/foobar/usr, automountd(8) intercepts the request and attempts to resolve the hostname foobar. If successful, automountd(8) automatically mounts the source export.

To enable autofs(5) at boot time, add this line to /etc/rc.conf:

Then autofs(5) can be started by running:

The autofs(5) map format is the same as in other operating systems. Information about this format from other sources can be useful, like the Mac OS X document.

Consult the automount(8), automountd(8), autounmountd(8), and auto_master(5) manual pages for more information.

Table 28.1 summarizes the terms and important processes used by NIS:

There are three types of hosts in an NIS environment:

Information in many files can be shared using NIS. The master.passwd, group, and hosts files are commonly shared via NIS. Whenever a process on a client needs information that would normally be found in these files locally, it makes a query to the NIS server that it is bound to instead.

This section describes a sample NIS environment which consists of 15 FreeBSD machines with no centralized point of administration. Each machine has its own /etc/passwd and /etc/master.passwd. These files are kept in sync with each other only through manual intervention. Currently, when a user is added to the lab, the process must be repeated on all 15 machines.

The configuration of the lab will be as follows:

If this is the first time an NIS scheme is being developed, it should be thoroughly planned ahead of time. Regardless of network size, several decisions need to be made as part of the planning process.

The canonical copies of all NIS files are stored on the master server. The databases used to store the information are called NIS maps. In FreeBSD, these maps are stored in /var/yp/[domainname] where [domainname] is the name of the NIS domain. Since multiple domains are supported, it is possible to have several directories, one for each domain. Each domain will have its own independent set of maps.

NIS master and slave servers handle all NIS requests through ypserv(8). This daemon is responsible for receiving incoming requests from NIS clients, translating the requested domain and map name to a path to the corresponding database file, and transmitting data from the database back to the client.

Setting up a master NIS server can be relatively straight forward, depending on environmental needs. Since FreeBSD provides built-in NIS support, it only needs to be enabled by adding the following lines to /etc/rc.conf:

Care must be taken in a multi-server domain where the server machines are also NIS clients. It is generally a good idea to force the servers to bind to themselves rather than allowing them to broadcast bind requests and possibly become bound to each other. Strange failure modes can result if one server goes down and others are dependent upon it. Eventually, all the clients will time out and attempt to bind to other servers, but the delay involved can be considerable and the failure mode is still present since the servers might bind to each other all over again.

A server that is also a client can be forced to bind to a particular server by adding these additional lines to /etc/rc.conf:

After saving the edits, type /etc/netstart to restart the network and apply the values defined in /etc/rc.conf. Before initializing the NIS maps, start ypserv(8):

To set up an NIS slave server, log on to the slave server and edit /etc/rc.conf as for the master server. Do not generate any NIS maps, as these already exist on the master server. When running ypinit on the slave server, use -s (for slave) instead of -m (for master). This option requires the name of the NIS master in addition to the domain name, as seen in this example:

This will generate a directory on the slave server called /var/yp/test-domain which contains copies of the NIS master server’s maps. Adding these /etc/crontab entries on each slave server will force the slaves to sync their maps with the maps on the master server:

These entries are not mandatory because the master server automatically attempts to push any map changes to its slaves. However, since clients may depend upon the slave server to provide correct password information, it is recommended to force frequent password map updates. This is especially important on busy networks where map updates might not always complete.

To finish the configuration, run /etc/netstart on the slave server in order to start the NIS services.

An NIS client binds to an NIS server using ypbind(8). This daemon broadcasts RPC requests on the local network. These requests specify the domain name configured on the client. If an NIS server in the same domain receives one of the broadcasts, it will respond to ypbind, which will record the server’s address. If there are several servers available, the client will use the address of the first server to respond and will direct all of its NIS requests to that server. The client will automatically ping the server on a regular basis to make sure it is still available. If it fails to receive a reply within a reasonable amount of time, ypbind will mark the domain as unbound and begin broadcasting again in the hopes of locating another server.

To configure a FreeBSD machine to be an NIS client:

To start the NIS client immediately, execute the following commands as the superuser:

After completing these steps, running ypcat passwd on the client should show the server’s passwd map.

Since RPC is a broadcast-based service, any system running ypbind within the same domain can retrieve the contents of the NIS maps. To prevent unauthorized transactions, ypserv(8) supports a feature called "securenets" which can be used to restrict access to a given set of hosts. By default, this information is stored in /var/yp/securenets, unless ypserv(8) is started with -p and an alternate path. This file contains entries that consist of a network specification and a network mask separated by white space. Lines starting with "#" are considered to be comments. A sample securenets might look like this:

If ypserv(8) receives a request from an address that matches one of these rules, it will process the request normally. If the address fails to match a rule, the request will be ignored and a warning message will be logged. If the securenets does not exist, ypserv will allow connections from any host.

TCP Wrapper is an alternate mechanism for providing access control instead of securenets. While either access control mechanism adds some security, they are both vulnerable to "IP spoofing" attacks. All NIS-related traffic should be blocked at the firewall.

Servers using securenets may fail to serve legitimate NIS clients with archaic TCP/IP implementations. Some of these implementations set all host bits to zero when doing broadcasts or fail to observe the subnet mask when calculating the broadcast address. While some of these problems can be fixed by changing the client configuration, other problems may force the retirement of these client systems or the abandonment of securenets.

The use of TCP Wrapper increases the latency of the NIS server. The additional delay may be long enough to cause timeouts in client programs, especially in busy networks with slow NIS servers. If one or more clients suffer from latency, convert those clients into NIS slave servers and force them to bind to themselves.

Barring specified users from logging on to individual systems becomes unscaleable on larger networks and quickly loses the main benefit of NIS: centralized administration.

Netgroups were developed to handle large, complex networks with hundreds of users and machines. Their use is comparable to UNIX® groups, where the main difference is the lack of a numeric ID and the ability to define a netgroup by including both user accounts and other netgroups.

To expand on the example used in this chapter, the NIS domain will be extended to add the users and systems shown in Tables 28.2 and 28.3:

When using netgroups to configure this scenario, each user is assigned to one or more netgroups and logins are then allowed or forbidden for all members of the netgroup. When adding a new machine, login restrictions must be defined for all netgroups. When a new user is added, the account must be added to one or more netgroups. If the NIS setup is planned carefully, only one central configuration file needs modification to grant or deny access to machines.

The first step is the initialization of the NIS netgroup map. In FreeBSD, this map is not created by default. On the NIS master server, use an editor to create a map named /var/yp/netgroup.

This example creates four netgroups to represent IT employees, IT apprentices, employees, and interns:

Each entry configures a netgroup. The first column in an entry is the name of the netgroup. Each set of parentheses represents either a group of one or more users or the name of another netgroup. When specifying a user, the three comma-delimited fields inside each group represent:

If a group contains multiple users, separate each user with whitespace. Additionally, each field may contain wildcards. See netgroup(5) for details.

Netgroup names longer than 8 characters should not be used. The names are case sensitive and using capital letters for netgroup names is an easy way to distinguish between user, machine and netgroup names.

Some non-FreeBSD NIS clients cannot handle netgroups containing more than 15 entries. This limit may be circumvented by creating several sub-netgroups with 15 users or fewer and a real netgroup consisting of the sub-netgroups, as seen in this example:

Repeat this process if more than 225 (15 times 15) users exist within a single netgroup.

To activate and distribute the new NIS map:

This will generate the three NIS maps netgroup, netgroup.byhost and netgroup.byuser. Use the map key option of ypcat(1) to check if the new NIS maps are available:

The output of the first command should resemble the contents of /var/yp/netgroup. The second command only produces output if host-specific netgroups were created. The third command is used to get the list of netgroups for a user.

To configure a client, use vipw(8) to specify the name of the netgroup. For example, on the server named war, replace this line:

with

This specifies that only the users defined in the netgroup IT_EMP will be imported into this system’s password database and only those users are allowed to login to this system.

This configuration also applies to the ~ function of the shell and all routines which convert between user names and numerical user IDs. In other words, cd ~user will not work, ls -l will show the numerical ID instead of the username, and find . -user joe -print will fail with the message No such user. To fix this, import all user entries without allowing them to login into the servers. This can be achieved by adding an extra line:

This line configures the client to import all entries but to replace the shell in those entries with /usr/sbin/nologin.

Make sure that extra line is placed after +@IT_EMP:::::::::. Otherwise, all user accounts imported from NIS will have /usr/sbin/nologin as their login shell and no one will be able to login to the system.

To configure the less important servers, replace the old +::::::::: on the servers with these lines:

The corresponding lines for the workstations would be:

NIS supports the creation of netgroups from other netgroups which can be useful if the policy regarding user access changes. One possibility is the creation of role-based netgroups. For example, one might create a netgroup called BIGSRV to define the login restrictions for the important servers, another netgroup called SMALLSRV for the less important servers, and a third netgroup called USERBOX for the workstations. Each of these netgroups contains the netgroups that are allowed to login onto these machines. The new entries for the NIS`netgroup` map would look like this:

This method of defining login restrictions works reasonably well when it is possible to define groups of machines with identical restrictions. Unfortunately, this is the exception and not the rule. Most of the time, the ability to define login restrictions on a per-machine basis is required.

Machine-specific netgroup definitions are another possibility to deal with the policy changes. In this scenario, the /etc/master.passwd of each system contains two lines starting with "+". The first line adds a netgroup with the accounts allowed to login onto this machine and the second line adds all other accounts with /usr/sbin/nologin as shell. It is recommended to use the "ALL-CAPS" version of the hostname as the name of the netgroup:

Once this task is completed on all the machines, there is no longer a need to modify the local versions of /etc/master.passwd ever again. All further changes can be handled by modifying the NIS map. Here is an example of a possible netgroup map for this scenario:

It may not always be advisable to use machine-based netgroups. When deploying a couple of dozen or hundreds of systems, role-based netgroups instead of machine-based netgroups may be used to keep the size of the NIS map within reasonable limits.

NIS requires that all hosts within an NIS domain use the same format for encrypting passwords. If users have trouble authenticating on an NIS client, it may be due to a differing password format. In a heterogeneous network, the format must be supported by all operating systems, where DES is the lowest common standard.

To check which format a server or client is using, look at this section of /etc/login.conf:

In this example, the system is using the DES format for password hashing. Other possible values include blf for Blowfish, md5 for MD5, sha256 and sha512 for SHA-256 and SHA-512 respectively. For more information and the up to date list of what is available on your system, consult the crypt(3) manpage.

If the format on a host needs to be edited to match the one being used in the NIS domain, the login capability database must be rebuilt after saving the change:

LDAP uses several terms which should be understood before starting the configuration. All directory entries consist of a group of attributes. Each of these attribute sets contains a unique identifier known as a Distinguished Name (DN) which is normally built from several other attributes such as the common or Relative Distinguished Name (RDN). Similar to how directories have absolute and relative paths, consider a DN as an absolute path and the RDN as the relative path.

An example LDAP entry looks like the following. This example searches for the entry for the specified user account (uid), organizational unit (ou), and organization (o):

This example entry shows the values for the dn, mail, cn, uid, and telephoneNumber attributes. The cn attribute is the RDN.

More information about LDAP and its terminology can be found at http://www.openldap.org/doc/admin24/intro.html.

FreeBSD does not provide a built-in LDAP server. Begin the configuration by installing net/openldap-server package or port:

There is a large set of default options enabled in the package. Review them by running pkg info openldap-server. If they are not sufficient (for example if SQL support is needed), please consider recompiling the port using the appropriate framework.

The installation creates the directory /var/db/openldap-data to hold the data. The directory to store the certificates must be created:

The next phase is to configure the Certificate Authority. The following commands must be executed from /usr/local/etc/openldap/private. This is important as the file permissions need to be restrictive and users should not have access to these files. More detailed information about certificates and their parameters can be found in OpenSSL. To create the Certificate Authority, start with this command and follow the prompts:

The entries for the prompts may be generic except for the Common Name. This entry must be different than the system hostname. If this will be a self signed certificate, prefix the hostname with CA for Certificate Authority.

The next task is to create a certificate signing request and a private key. Input this command and follow the prompts:

During the certificate generation process, be sure to correctly set the Common Name attribute. The Certificate Signing Request must be signed with the Certificate Authority in order to be used as a valid certificate:

The final part of the certificate generation process is to generate and sign the client certificates:

Remember to use the same Common Name attribute when prompted. When finished, ensure that a total of eight (8) new files have been generated through the proceeding commands.

The daemon running the OpenLDAP server is slapd. Its configuration is performed through slapd.ldif: the old slapd.conf has been deprecated by OpenLDAP.

Configuration examples for slapd.ldif are available and can also be found in /usr/local/etc/openldap/slapd.ldif.sample. Options are documented in slapd-config(5). Each section of slapd.ldif, like all the other LDAP attribute sets, is uniquely identified through a DN. Be sure that no blank lines are left between the dn: statement and the desired end of the section. In the following example, TLS will be used to implement a secure channel. The first section represents the global configuration:

The Certificate Authority, server certificate and server private key files must be specified here. It is recommended to let the clients choose the security cipher and omit option olcTLSCipherSuite (incompatible with TLS clients other than openssl). Option olcTLSProtocolMin lets the server require a minimum security level: it is recommended. While verification is mandatory for the server, it is not for the client: olcTLSVerifyClient: never.

The second section is about the backend modules and can be configured as follows:

The third section is devoted to load the needed ldif schemas to be used by the databases: they are essential.

Next, the frontend configuration section:

Another section is devoted to the configuration backend, the only way to later access the OpenLDAP server configuration is as a global super-user.

The default administrator username is cn=config. Type slappasswd in a shell, choose a password and use its hash in olcRootPW. If this option is not specified now, before slapd.ldif is imported, no one will be later able to modify the global configuration section.

The last section is about the database backend:

This database hosts the actual contents of the LDAP directory. Types other than mdb are available. Its super-user, not to be confused with the global one, is configured here: a (possibly custom) username in olcRootDN and the password hash in olcRootPW; slappasswd can be used as before.

This repository contains four examples of slapd.ldif. To convert an existing slapd.conf into slapd.ldif, refer to this page (please note that this may introduce some unuseful options).

When the configuration is completed, slapd.ldif must be placed in an empty directory. It is recommended to create it as:

Import the configuration database:

Start the slapd daemon:

Option -d can be used for debugging, as specified in slapd(8). To verify that the server is running and working:

The server must still be trusted. If that has never been done before, follow these instructions. Install the OpenSSL package or port:

From the directory where ca.crt is stored (in this example, /usr/local/etc/openldap), run:

Both the CA and the server certificate are now correctly recognized in their respective roles. To verify this, run this command from the server.crt directory:

If slapd was running, restart it. As stated in /usr/local/etc/rc.d/slapd, to properly run slapd at boot the following lines must be added to /etc/rc.conf:

slapd does not provide debugging at boot. Check /var/log/debug.log, dmesg -a and /var/log/messages for this purpose.

The following example adds the group team and the user john to the domain.example LDAP database, which is still empty. First, create the file domain.ldif:

See the OpenLDAP documentation for more details. Use slappasswd to replace the plain text password secret with a hash in userPassword. The path specified as loginShell must exist in all the systems where john is allowed to login. Finally, use the mdb administrator to modify the database:

Modifications to the global configuration section can only be performed by the global super-user. For example, assume that the option olcTLSCipherSuite: HIGH:MEDIUM:SSLv3 was initially specified and must now be deleted. First, create a file that contains the following:

Then, apply the modifications:

When asked, provide the password chosen in the configuration backend section. The username is not required: here, cn=config represents the DN of the database section to be modified. Alternatively, use ldapmodify to delete a single line of the database, ldapdelete to delete a whole entry.

If something goes wrong, or if the global super-user cannot access the configuration backend, it is possible to delete and re-write the whole configuration:

slapd.ldif can then be edited and imported again. Please, follow this procedure only when no other solution is available.

This is the configuration of the server only. The same machine can also host an LDAP client, with its own separate configuration.

DHCP client support is included in the FreeBSD installer, making it easy to configure a newly installed system to automatically receive its networking addressing information from an existing DHCP server. Refer to Accounts, Time Zone, Services and Hardening for examples of network configuration.

When dhclient is executed on the client machine, it begins broadcasting requests for configuration information. By default, these requests use UDP port 68. The server replies on UDP port 67, giving the client an IP address and other relevant network information such as a subnet mask, default gateway, and DNS server addresses. This information is in the form of a DHCP "lease" and is valid for a configurable time. This allows stale IP addresses for clients no longer connected to the network to automatically be reused. DHCP clients can obtain a great deal of information from the server. An exhaustive list may be found in dhcp-options(5).

By default, when a FreeBSD system boots, its DHCP client runs in the background, or asynchronously. Other startup scripts continue to run while the DHCP process completes, which speeds up system startup.

Background DHCP works well when the DHCP server responds quickly to the client’s requests. However, DHCP may take a long time to complete on some systems. If network services attempt to run before DHCP has assigned the network addressing information, they will fail. Using DHCP in synchronous mode prevents this problem as it pauses startup until the DHCP configuration has completed.

This line in /etc/rc.conf is used to configure background or asynchronous mode:

This line may already exist if the system was configured to use DHCP during installation. Replace the fxp0 shown in these examples with the name of the interface to be dynamically configured, as described in “Setting Up Network Interface Cards”.

To instead configure the system to use synchronous mode, and to pause during startup while DHCP completes, use “SYNCDHCP”:

Additional client options are available. Search for dhclient in rc.conf(5) for details.

The DHCP client uses the following files:

This section demonstrates how to configure a FreeBSD system to act as a DHCP server using the Internet Systems Consortium (ISC) implementation of the DHCP server. This implementation and its documentation can be installed using the net/isc-dhcp44-server package or port.

The installation of net/isc-dhcp44-server installs a sample configuration file. Copy /usr/local/etc/dhcpd.conf.example to /usr/local/etc/dhcpd.conf and make any edits to this new file.

The configuration file is comprised of declarations for subnets and hosts which define the information that is provided to DHCP clients. For example, these lines configure the following:

This configuration file supports many more options. Refer to dhcpd.conf(5), installed with the server, for details and examples.

Once the configuration of dhcpd.conf is complete, enable the DHCP server in /etc/rc.conf:

Replace the dc0 with the interface (or interfaces, separated by whitespace) that the DHCP server should listen on for DHCP client requests.

Start the server by issuing the following command:

Any future changes to the configuration of the server will require the dhcpd service to be stopped and then started using service(8).

The DHCP server uses the following files. Note that the manual pages are installed with the server software.

Name servers generally come in two forms: authoritative name servers, and caching (also known as resolving) name servers.

An authoritative name server is needed when:

A caching name server is needed when:

When one queries for www.FreeBSD.org, the resolver usually queries the uplink ISP’s name server, and retrieves the reply. With a local, caching DNS server, the query only has to be made once to the outside world by the caching DNS server. Additional queries will not have to go outside the local network, since the information is cached locally.

Unbound is provided in the FreeBSD base system. By default, it will provide DNS resolution to the local machine only. While the base system package can be configured to provide resolution services beyond the local machine, it is recommended that such requirements be addressed by installing Unbound from the FreeBSD Ports Collection.

To enable Unbound, add the following to /etc/rc.conf:

Any existing nameservers in /etc/resolv.conf will be configured as forwarders in the new Unbound configuration.

Once each nameserver is confirmed to support DNSSEC, start Unbound:

This will take care of updating /etc/resolv.conf so that queries for DNSSEC secured domains will now work. For example, run the following to validate the FreeBSD.org DNSSEC trust tree:

FreeBSD does not provide authoritative name server software in the base system. Users are encouraged to install third party applications, like dns/nsd or dns/bind918 package or port.

One of the popular implementations of zeroconf is Avahi. Avahi can be installed and configured with the following commands:

In FreeBSD, the main Apache HTTP Server configuration file is installed as /usr/local/etc/apache2x/httpd.conf, where x represents the version number. This ASCII text file begins comment lines with a #. The most frequently modified directives are:

It is always a good idea to make a backup copy of the default Apache configuration file before making changes. When the configuration of Apache is complete, save the file and verify the configuration using apachectl. Running apachectl configtest should return Syntax OK.

To launch Apache at system startup, add the following line to /etc/rc.conf:

If Apache should be started with non-default options, the following line may be added to /etc/rc.conf to specify the needed flags:

If apachectl does not report configuration errors, start httpd now:

The httpd service can be tested by entering http://localhost in a web browser, replacing localhost with the fully-qualified domain name of the machine running httpd. The default web page that is displayed is /usr/local/www/apache24/data/index.html.

The Apache configuration can be tested for errors after making subsequent configuration changes while httpd is running using the following command:

Virtual hosting allows multiple websites to run on one Apache server. The virtual hosts can be IP-based or name-based. IP-based virtual hosting uses a different IP address for each website. Name-based virtual hosting uses the clients HTTP/1.1 headers to figure out the hostname, which allows the websites to share the same IP address.

To setup Apache to use name-based virtual hosting, add a VirtualHost block for each website. For example, for the webserver named www.domain.tld with a virtual domain of www.someotherdomain.tld, add the following entries to httpd.conf:

For each virtual host, replace the values for ServerName and DocumentRoot with the values to be used.

For more information about setting up virtual hosts, consult the official Apache documentation at: http://httpd.apache.org/docs/vhosts/.

Apache uses modules to augment the functionality provided by the basic server. Refer to http://httpd.apache.org/docs/current/mod/ for a complete listing of and the configuration details for the available modules.

In FreeBSD, some modules can be compiled with the www/apache24 port. Type make config within /usr/ports/www/apache24 to see which modules are available and which are enabled by default. If the module is not compiled with the port, the FreeBSD Ports Collection provides an easy way to install many modules. This section describes three of the most commonly used modules.

In addition to mod_perl and mod_php, other languages are available for creating dynamic web content. These include Django and Ruby on Rails.

The most important configuration step is deciding which accounts will be allowed access to the FTP server. A FreeBSD system has a number of system accounts which should not be allowed FTP access. The list of users disallowed any FTP access can be found in /etc/ftpusers. By default, it includes system accounts. Additional users that should not be allowed access to FTP can be added.

In some cases it may be desirable to restrict the access of some users without preventing them completely from using FTP. This can be accomplished be creating /etc/ftpchroot as described in ftpchroot(5). This file lists users and groups subject to FTP access restrictions.

To enable anonymous FTP access to the server, create a user named ftp on the FreeBSD system. Users will then be able to log on to the FTP server with a username of ftp or anonymous. When prompted for the password, any input will be accepted, but by convention, an email address should be used as the password. The FTP server will call chroot(2) when an anonymous user logs in, to restrict access to only the home directory of the ftp user.

There are two text files that can be created to specify welcome messages to be displayed to FTP clients. The contents of /etc/ftpwelcome will be displayed to users before they reach the login prompt. After a successful login, the contents of /etc/ftpmotd will be displayed. Note that the path to this file is relative to the login environment, so the contents of ~ftp/etc/ftpmotd would be displayed for anonymous users.

Once the FTP server has been configured, set the appropriate variable in /etc/rc.conf to start the service during boot:

To start the service now:

Test the connection to the FTP server by typing:

The ftpd daemon uses syslog(3) to log messages. By default, the system log daemon will write messages related to FTP in /var/log/xferlog. The location of the FTP log can be modified by changing the following line in /etc/syslog.conf:

Samba is configured in /usr/local/etc/smb4.conf. This file must be created before Samba can be used.

A simple smb4.conf to share directories and printers with Windows® clients in a workgroup is shown here. For more complex setups involving LDAP or Active Directory, it is easier to use samba-tool(8) to create the initial smb4.conf.

To enable Samba at boot time, add the following line to /etc/rc.conf:

To start Samba now:

Samba consists of three separate daemons. Both the nmbd and smbd daemons are started by samba_enable. If winbind name resolution is also required, set:

Samba can be stopped at any time by typing:

Samba is a complex software suite with functionality that allows broad integration with Microsoft® Windows® networks. For more information about functionality beyond the basic configuration described here, refer to https://www.samba.org.

On FreeBSD, the built-in ntpd can be used to synchronize a system’s clock. ntpd is configured using rc.conf(5) variables and /etc/ntp.conf, as detailed in the following sections.

ntpd communicates with its network peers using UDP packets. Any firewalls between your machine and its NTP peers must be configured to allow UDP packets in and out on port 123.

ntpd does not need a permanent connection to the Internet to function properly. However, if a PPP connection is configured to dial out on demand, NTP traffic should be prevented from triggering a dial out or keeping the connection alive. This can be configured with filter directives in /etc/ppp/ppp.conf. For example:

For more details, refer to the PACKET FILTERING section in ppp(8) and the examples in /usr/share/examples/ppp/.

To configure an iSCSI target, create the /etc/ctl.conf configuration file, add a line to /etc/rc.conf to make sure the ctld(8) daemon is automatically started at boot, and then start the daemon.

The following is an example of a simple /etc/ctl.conf configuration file. Refer to ctl.conf(5) for a complete description of this file’s available options.

The first entry defines the pg0 portal group. Portal groups define which network addresses the ctld(8) daemon will listen on. The discovery-auth-group no-authentication entry indicates that any initiator is allowed to perform iSCSI target discovery without authentication. Lines three and four configure ctld(8) to listen on all IPv4 (listen 0.0.0.0) and IPv6 (listen [::]) addresses on the default port of 3260.

It is not necessary to define a portal group as there is a built-in portal group called default. In this case, the difference between default and pg0 is that with default, target discovery is always denied, while with pg0, it is always allowed.

The second entry defines a single target. Target has two possible meanings: a machine serving iSCSI or a named group of LUNs. This example uses the latter meaning, where iqn.2012-06.com.example:target0 is the target name. This target name is suitable for testing purposes. For actual use, change com.example to the real domain name, reversed. The 2012-06 represents the year and month of acquiring control of that domain name, and target0 can be any value. Any number of targets can be defined in this configuration file.

The auth-group no-authentication line allows all initiators to connect to the specified target and portal-group pg0 makes the target reachable through the pg0 portal group.

The next section defines the LUN. To the initiator, each LUN will be visible as a separate disk device. Multiple LUNs can be defined for each target. Each LUN is identified by a number, where LUN 0 is mandatory. The path /data/target0-0 line defines the full path to a file or zvol backing the LUN. That path must exist before starting ctld(8). The second line is optional and specifies the size of the LUN.

Next, to make sure the ctld(8) daemon is started at boot, add this line to /etc/rc.conf:

To start ctld(8) now, run this command:

As the ctld(8) daemon is started, it reads /etc/ctl.conf. If this file is edited after the daemon starts, use this command so that the changes take effect immediately:

The iSCSI initiator requires that the iscsid(8) daemon is running. This daemon does not use a configuration file. To start it automatically at boot, add this line to /etc/rc.conf:

To start iscsid(8) now, run this command:

Connecting to a target can be done with or without an /etc/iscsi.conf configuration file. This section demonstrates both types of connections.