Intro to BSD for Linux Users Darren Reed

Intro to BSD for Linux Users. Darren Reed Tel. Net Media

Introduction n BSD from a Linux point of view.

Topics of Discussion n Licensing. History of Unix/BSD software distributions.

Licensing n n BSD License is more free than GPL - only restriction is in attribution of original work. No requirement to use the same license. u BSD’s can contain different licenses, although discouraged.

Licensing Continued. n n n BSD License attempts to encourage commercial use. Commercial use of GPL requires permission from all author’s. Cannot intimately integrate GPL based products due to restrictions in GPL whereas the reverse is possible.

BSD History n A branch off the original Unix software tree. u ARPA funded development of TCP/IP at Berkeley. u Much TCP/IP research/development still around BSD’s (KAME, etc). n n 4. 2 & 4. 3 BSD used by Sun/Digital as a base for Sun. OS 4/Ultrix, etc. History

Modern BSD History n Copyright problems. u Tainted n source code. Branches of BSD since Net/2 u 386 BSD, BSD/OS, Free. BSD, Net. BSD, Open. BSD

BSD Branches n Each of the branches is a complete OS u I. e. each of the BSD’s is like “Red. Hat Linux”. n n Kernel is not maintained separately. Only some software is GNU derived - gcc, etc. u Base OS already contains many of the required tools such as /bin/ls.

Net. BSD n n n www. netbsd. org First free multi-platform operating system. Primary goal is to provide a modern, stable, Unix environment for multiple platforms. Ports are known as Net. BSD/sparc, Net. BSD/ppc, etc, c. f. Sparc. Linux. Same source code (CVS repository) is used on all ports.

Free. BSD n n www. freebsd. org Behind cdrom. com. Aggressive release schedule. Primary focus is on PC support. u Now an Alpha port.

BSD/OS (BSD Inc. ) n n Product of BSD Inc. www. bsdi. com Only commercial BSD operating system available. Source code is not included in base distribution. Primarily aimed at PC hardware u Limited availability for SPARC platform. n Very easy to install (easiest PC

Open. BSD n n n www. openbsd. org Branched off from Net. BSD in 199 X, founded by Theo. Primary focus is on security. u Completely n audited. Base distribution includes Ipsec, IPv 6. u Based in Canada.

Project Organisation. n Linux source code is controlled centrally. u Utilities n from diverse sources. BSD groups have development teams. u Members have read-write access to entire CVS tree. n Coding style u Net. BSD Form). KNF (Kernel Normal

OS Organisation n Installed into a single partition type, each now has their own type. u Free. BSD n BSD disk label enables u n up to 8 FFS partitions (a-h). Free. BSD supports slices on PC’s u slice n 165, Net. BSD 169, etc. 0 is DOS partition 1, etc. Different methods for accessing other partitions.

SVR 4 Impact n n Shared memory, semaphores, etc. rc script organisation is still BSD.

Code Sharing n n n Common base makes application compatibility less of a problem. Some kernel source can be shared. Now large differences between kernels. u Vague API. attempts to resynchronise

Emulation n n Linuxemulation. Net. BSD ports. u Solaris, n Sun. OS, HP, Tru 64. a. out & ELF.

Kernel Configuration n Single text configuration file used to build kernels. u Not menu/GUI driven as configuration is not “yes/no” n Free. BSD supports boot-time device configuration (boot -c) u Versions 2. 2. * allowed device configuration to be saved, not yet in 3. * kernels. n Can easily build multiple kernels in the same source tree.

Device Configuration n n Some LKM support for devices. Devices can be wired down. u sd 0 at scsibus 0 target 3 u sd 1 at scsibus 0 target 0 u etc. n Net. BSD/Open. BSD support newconfig with wildcards. u sd 0 at scsibus* target 3 u sd? at scsibus* target ?

Booting n n Boot selector in MBR. BSD’s use two stage boot. u Second n stage understands FFS. Kernel selection not fixed. u I. e. you don’t need to re-run lilo if you’ve installed a new kernel. n Root on NFS - automatic detection.

Networking n n No”Net 2”, “Net 3” separate TCP/IP versions. mbufs are still used (some performance penalties). u And performance is often dependant on driver capabilities.

Firewall n IP Filter runs on all *BSD platforms u Net. BSD, Open. BSD ship it as their native firewall application. n n BSD/OS 4. x has its own BPF based suite of tools. Free. BSD uses ipfw (common ancestory with ipfwadm). u “divert” sockets used for NAT (natd = poor performance) u improved syntax.

Security n some BSD bugs appear to be emulated in Linux : ) u e. g. n n mmap(2) and file flags. TCP wrappers provided. Open. BSD - audited. u Bugs found in others - e. g. Net. BSD - which aren’t fixed in Open. BSD. n Securelevels, file flags, etc.

Setup n Shadow password file: master. passed u /etc/passwd, pwd. db, spwd. db

Software Distributions n n n Entire OS is of the same release. Applications are always in sync with the kernel. Installation files available for all Net. BSD platforms from one central site.

Software Bundles n X 11 R 6 u XFree 86 n used where applicable. RPM-like package management available. u Tcsh, bash, etc.

Future n n n Linux compatibility (important!) Kernel threads, true SMP. More spin-offs ? Unlikely. . .