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+---
+title: FreeBSD Quickstart Guide for Linux® Users
+authors:
+  - author: John Ferrell
+copyright: 2008 The FreeBSD Documentation Project
+releaseinfo: "$FreeBSD$" 
+trademarks: ["freebsd", "intel", "redhat", "linux", "unix", "general"]
+---
+
+= FreeBSD Quickstart Guide for Linux(R) Users
+:doctype: article
+:toc: macro
+:toclevels: 1
+:icons: font
+:sectnums:
+:sectnumlevels: 6
+:source-highlighter: rouge
+:experimental:
+
+include::shared/en/urls.adoc[]
+
+[.abstract-title]
+Abstract
+
+This document is intended to quickly familiarize intermediate to advanced Linux(R) users with the basics of FreeBSD.
+
+'''
+
+toc::[]
+
+[[intro]]
+== Introduction
+
+This document highlights some of the technical differences between FreeBSD and Linux(R) so that intermediate to advanced Linux(R) users can quickly familiarize themselves with the basics of FreeBSD.
+
+This document assumes that FreeBSD is already installed. Refer to the link:{handbook}#bsdinstall[Installing FreeBSD] chapter of the FreeBSD Handbook for help with the installation process.
+
+[[shells]]
+== Default Shell
+
+Linux(R) users are often surprised to find that Bash is not the default shell in FreeBSD. In fact, Bash is not included in the default installation. Instead, FreeBSD uses man:tcsh[1] as the default root shell, and the Bourne shell-compatible man:sh[1] as the default user shell. man:sh[1] is very similar to Bash but with a much smaller feature-set. Generally shell scripts written for man:sh[1] will run in Bash, but the reverse is not always true.
+
+However, Bash and other shells are available for installation using the FreeBSD link:{handbook}#ports[Packages and Ports Collection].
+
+After installing another shell, use man:chsh[1] to change a user's default shell. It is recommended that the `root` user's default shell remain unchanged since shells which are not included in the base distribution are installed to [.filename]#/usr/local/bin#. In the event of a problem, the file system where [.filename]#/usr/local/bin# is located may not be mounted. In this case, `root` would not have access to its default shell, preventing `root` from logging in and fixing the problem.
+
+[[software]]
+== Packages and Ports: Adding Software in FreeBSD
+
+FreeBSD provides two methods for installing applications: binary packages and compiled ports. Each method has its own benefits:
+
+.Binary Packages
+* Faster installation as compared to compiling large applications.
+* Does not require an understanding of how to compile software.
+* No need to install a compiler.
+
+.Ports
+* Ability to customize installation options.
+* Custom patches can be applied.
+
+If an application installation does not require any customization, installing the package is sufficient. Compile the port instead whenever an application requires customization of the default options. If needed, a custom package can be compiled from ports using `make package`.
+
+A complete list of all available ports and packages can be found https://www.freebsd.org/ports/[here].
+
+[[packages]]
+=== Packages
+
+Packages are pre-compiled applications, the FreeBSD equivalents of [.filename]#.deb# files on Debian/Ubuntu based systems and [.filename]#.rpm# files on Red Hat/Fedora based systems. Packages are installed using `pkg`. For example, the following command installs Apache 2.4:
+
+[source,bash]
+....
+# pkg install apache24
+....
+
+For more information on packages refer to section 5.4 of the FreeBSD Handbook: link:{handbook}#pkgng-intro[Using pkgng for Binary Package Management].
+
+[[ports]]
+=== Ports
+
+The FreeBSD Ports Collection is a framework of [.filename]#Makefiles# and patches specifically customized for installing applications from source on FreeBSD. When installing a port, the system will fetch the source code, apply any required patches, compile the code, and install the application and any required dependencies.
+
+The Ports Collection, sometimes referred to as the ports tree, can be installed to [.filename]#/usr/ports# using man:portsnap[8]. Detailed instructions for installing the Ports Collection can be found in link:{handbook}#ports-using[section 5.5] of the FreeBSD Handbook.
+
+To compile a port, change to the port's directory and start the build process. The following example installs Apache 2.4 from the Ports Collection:
+
+[source,bash]
+....
+# cd /usr/ports/www/apache24
+# make install clean
+....
+
+A benefit of using ports to install software is the ability to customize the installation options. This example specifies that the mod_ldap module should also be installed:
+
+[source,bash]
+....
+# cd /usr/ports/www/apache24
+# make WITH_LDAP="YES" install clean
+....
+
+Refer to link:{handbook}#ports-using[Using the Ports Collection] for more information.
+
+[[startup]]
+== System Startup
+
+Many Linux(R) distributions use the SysV init system, whereas FreeBSD uses the traditional BSD-style man:init[8]. Under the BSD-style man:init[8], there are no run-levels and [.filename]#/etc/inittab# does not exist. Instead, startup is controlled by man:rc[8] scripts. At system boot, [.filename]#/etc/rc# reads [.filename]#/etc/rc.conf# and [.filename]#/etc/defaults/rc.conf# to determine which services are to be started. The specified services are then started by running the corresponding service initialization scripts located in [.filename]#/etc/rc.d/# and [.filename]#/usr/local/etc/rc.d/#. These scripts are similar to the scripts located in [.filename]#/etc/init.d/# on Linux(R) systems.
+
+The scripts found in [.filename]#/etc/rc.d/# are for applications that are part of the "base" system, such as man:cron[8], man:sshd[8], and man:syslog[3]. The scripts in [.filename]#/usr/local/etc/rc.d/# are for user-installed applications such as Apache and Squid.
+
+Since FreeBSD is developed as a complete operating system, user-installed applications are not considered to be part of the "base" system. User-installed applications are generally installed using link:{handbook}#ports-using[Packages or Ports]. In order to keep them separate from the base system, user-installed applications are installed under [.filename]#/usr/local/#. Therefore, user-installed binaries reside in [.filename]#/usr/local/bin/#, configuration files are in [.filename]#/usr/local/etc/#, and so on.
+
+Services are enabled by adding an entry for the service in [.filename]#/etc/rc.conf# . The system defaults are found in [.filename]#/etc/defaults/rc.conf# and these default settings are overridden by settings in [.filename]#/etc/rc.conf#. Refer to man:rc.conf[5] for more information about the available entries. When installing additional applications, review the application's install message to determine how to enable any associated services.
+
+The following entries in [.filename]#/etc/rc.conf# enable man:sshd[8], enable Apache 2.4, and specify that Apache should be started with SSL.
+
+[.programlisting]
+....
+# enable SSHD
+sshd_enable="YES"
+# enable Apache with SSL
+apache24_enable="YES"
+apache24_flags="-DSSL"
+....
+
+Once a service has been enabled in [.filename]#/etc/rc.conf#, it can be started without rebooting the system:
+
+[source,bash]
+....
+# service sshd start
+# service apache24 start
+....
+
+If a service has not been enabled, it can be started from the command line using `onestart`:
+
+[source,bash]
+....
+# service sshd onestart
+....
+
+[[network]]
+== Network Configuration
+
+Instead of a generic _ethX_ identifier that Linux(R) uses to identify a network interface, FreeBSD uses the driver name followed by a number. The following output from man:ifconfig[8] shows two Intel(R) Pro 1000 network interfaces ([.filename]#em0# and [.filename]#em1#):
+
+[source,bash]
+....
+% ifconfig
+em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
+        options=b<RXCSUM,TXCSUM,VLAN_MTU>
+        inet 10.10.10.100 netmask 0xffffff00 broadcast 10.10.10.255
+        ether 00:50:56:a7:70:b2
+        media: Ethernet autoselect (1000baseTX <full-duplex>)
+        status: active
+em1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
+        options=b<RXCSUM,TXCSUM,VLAN_MTU>
+        inet 192.168.10.222 netmask 0xffffff00 broadcast 192.168.10.255
+        ether 00:50:56:a7:03:2b
+        media: Ethernet autoselect (1000baseTX <full-duplex>)
+        status: active
+....
+
+An IP address can be assigned to an interface using man:ifconfig[8]. To remain persistent across reboots, the IP configuration must be included in [.filename]#/etc/rc.conf#. The following [.filename]#/etc/rc.conf# entries specify the hostname, IP address, and default gateway:
+
+[.programlisting]
+....
+hostname="server1.example.com"
+ifconfig_em0="inet 10.10.10.100 netmask 255.255.255.0"
+defaultrouter="10.10.10.1"
+....
+
+Use the following entries to instead configure an interface for DHCP:
+
+[.programlisting]
+....
+hostname="server1.example.com"
+ifconfig_em0="DHCP"
+....
+
+[[firewall]]
+== Firewall
+
+FreeBSD does not use Linux(R) IPTABLES for its firewall. Instead, FreeBSD offers a choice of three kernel level firewalls:
+
+* link:{handbook}#firewalls-pf[PF]
+* link:{handbook}#firewalls-ipf[IPFILTER]
+* link:{handbook}#firewalls-ipfw[IPFW]
+
+PF is developed by the OpenBSD project and ported to FreeBSD. PF was created as a replacement for IPFILTER and its syntax is similar to that of IPFILTER. PF can be paired with man:altq[4] to provide QoS features.
+
+This sample PF entry allows inbound SSH:
+
+[.programlisting]
+....
+pass in on $ext_if inet proto tcp from any to ($ext_if) port 22
+....
+
+IPFILTER is the firewall application developed by Darren Reed. It is not specific to FreeBSD and has been ported to several operating systems including NetBSD, OpenBSD, SunOS, HP/UX, and Solaris.
+
+The IPFILTER syntax to allow inbound SSH is:
+
+[.programlisting]
+....
+pass in on $ext_if proto tcp from any to any port = 22
+....
+
+IPFW is the firewall developed and maintained by FreeBSD. It can be paired with man:dummynet[4] to provide traffic shaping capabilities and simulate different types of network connections.
+
+The IPFW syntax to allow inbound SSH would be:
+
+[.programlisting]
+....
+ipfw add allow tcp from any to me 22 in via $ext_if
+....
+
+[[updates]]
+== Updating FreeBSD
+
+There are two methods for updating a FreeBSD system: from source or binary updates.
+
+Updating from source is the most involved update method, but offers the greatest amount of flexibility. The process involves synchronizing a local copy of the FreeBSD source code with the FreeBSD Subversion servers. Once the local source code is up-to-date, a new version of the kernel and userland can be compiled.
+
+Binary updates are similar to using `yum` or `apt-get` to update a Linux(R) system. In FreeBSD, man:freebsd-update[8] can be used fetch new binary updates and install them. These updates can be scheduled using man:cron[8].
+
+[NOTE]
+====
+When using man:cron[8] to schedule updates, use `freebsd-update cron` in the man:crontab[1] to reduce the possibility of a large number of machines all pulling updates at the same time:
+
+[.programlisting]
+....
+0 3 * * * root /usr/sbin/freebsd-update cron
+....
+
+====
+
+For more information on source and binary updates, refer to link:{handbook}#updating-upgrading[the chapter on updating] in the FreeBSD Handbook.
+
+[[procfs]]
+== procfs: Gone But Not Forgotten
+
+In some Linux(R) distributions, one could look at [.filename]#/proc/sys/net/ipv4/ip_forward# to determine if IP forwarding is enabled. In FreeBSD, man:sysctl[8] is instead used to view this and other system settings.
+
+For example, use the following to determine if IP forwarding is enabled on a FreeBSD system:
+
+[source,bash]
+....
+% sysctl net.inet.ip.forwarding
+net.inet.ip.forwarding: 0
+....
+
+Use `-a` to list all the system settings:
+
+[source,bash]
+....
+% sysctl -a | more
+....
+
+If an application requires procfs, add the following entry to [.filename]#/etc/fstab#:
+
+[source,bash]
+....
+proc                /proc           procfs  rw,noauto       0       0
+....
+
+Including `noauto` will prevent [.filename]#/proc# from being automatically mounted at boot.
+
+To mount the file system without rebooting:
+
+[source,bash]
+....
+# mount /proc
+....
+
+[[commands]]
+== Common Commands
+
+Some common command equivalents are as follows:
+
+[.informaltable]
+[cols="1,1,1", frame="none", options="header"]
+|===
+| Linux(R) command (Red Hat/Debian)
+| FreeBSD equivalent
+| Purpose
+
+|`yum install _package_` / `apt-get install _package_`
+|`pkg install _package_`
+|Install package from remote repository
+
+|`rpm -ivh _package_` / `dpkg -i _package_`
+|`pkg add _package_`
+|Install local package
+
+|`rpm -qa` / `dpkg -l`
+|`pkg info`
+|List installed packages
+
+|`lspci`
+|`pciconf`
+|List PCI devices
+
+|`lsmod`
+|`kldstat`
+|List loaded kernel modules
+
+|`modprobe`
+|`kldload` / `kldunload`
+|Load/Unload kernel modules
+
+|`strace`
+|`truss`
+|Trace system calls
+|===
+
+[[conclusion]]
+== Conclusion
+
+This document has provided an overview of FreeBSD. Refer to the link:{handbook}[FreeBSD Handbook] for more in-depth coverage of these topics as well as the many topics not covered by this document.