For the OpenBSD base system, security fixes are normally applied to the two most recent releases. There are four options:
-uflag to get the new files.
/usr/ports/infrastructure/bin/pkg_outdatedscript to list any packages in need of rebuilding, and issue
make updatein the affected port directory. In some cases, existing ports will need to be uninstalled before rebuilding. To be alerted of port updates, consider following the ports-changes mailing list.
Most daemons and services that come with OpenBSD are controlled on boot by variables defined in /etc/rc.conf. You'll see lines similar to this:
httpd_flags=NOThis shows that httpd(8) is not to be started from rc(8) at boot time. Each line has a comment showing you the flags for common usage of that daemon or service.
Do not alter rc.conf(8) directly.
Instead, use the rcctl(8) utility
to maintain the
This makes future upgrades easier as all the changes are in the one file that
isn't touched during upgrade.
For example, to start the apmd(8) daemon for CPU scaling, one might do:
# rcctl enable apmd # rcctl set apmd flags -A # rcctl start apmd
For example, if appropriately configured, the following command would display root's crontab(5) file:
$ doas -u root crontab -lCommands invoked by doas(1) are logged to
/var/log/secureby default. Check the doas.conf(5) manual for configuration examples.
/etc/master.passwdand is only readable by root. The pwd_mkdb(8) tool generates the world-readable
/etc/passwdand the password databases (
/etc/spwd.db) from the main file. The format is described in passwd(5).
Always use vipw(8) to edit your
After you are done editing, it will first sanity check the changes, then
/etc/passwd and the password databases, and finally
install the copy in place of the original
WARNING: One-time password systems only protect authentication information. They do not prevent network eavesdroppers from gaining access to private information. Furthermore, if you are accessing a secure system A, it is recommended that you do this from another trusted system B, to ensure nobody is gaining access to system A by logging your keystrokes or by capturing and/or forging input and output on your terminal devices.
/etc/skeymust exist. If this directory doesn't exist, have the superuser create it by doing:
# skeyinit -EThen use skeyinit(1) to initialize your S/Key. You will first be prompted for your login password, then you will be asked for your S/Key secret passphrase, which must be at least 10 characters long:
$ skeyinit Password: [Adding ericj with md5] Enter new secret passphrase: Again secret passphrase: ID ericj skey is otp-md5 100 oshi45820 Next login password: HAUL BUS JAKE DING HOT HOGNotice the information in the last two lines. The program used to create your S/Key password is otp-md5(1), the sequence number is
100and the secret key is
oshi45820. The six small words
HAUL BUS JAKE DING HOT HOGconstitute the S/Key password with sequence number
$ skeyinfo -v otp-md5 95 oshi45820 $ otp-md5 95 oshi45820 Enter secret passphrase: NOOK CHUB HOYT SAC DOLE FUMEIn order to generate a list of S/Key passwords, do:
$ otp-md5 -n 5 95 oshi45820 Enter secret passphrase: 91: SHIM SET LEST HANS SMUG BOOT 92: SUE ARTY YAW SEED KURD BAND 93: JOEY SOOT PHI KYLE CURT REEK 94: WIRE BOGY MESS JUDE RUNT ADD 95: NOOK CHUB HOYT SAC DOLE FUME
localhost. To perform an S/Key login, you append
:skeyto your login name.
$ ftp localhost Connected to localhost. 220 oshibana.shin.ms FTP server (Version 6.5/OpenBSD) ready. Name (localhost:ericj): ericj:skey 331- otp-md5 93 oshi45820 331 S/Key Password: JOEY SOOT PHI KYLE CURT REEK [...] 230 User ericj logged in. Remote system type is UNIX. Using binary mode to transfer files. ftp> quit 221 Goodbye.Similarly, for ssh(1):
$ ssh -l ericj:skey localhost otp-md5 91 oshi45821 S/Key Password: SHIM SET LEST HANS SMUG BOOT Last login: Thu Apr 7 12:21:48 on ttyp1 from 184.108.40.206 $
Of course, you could use various directory services on OpenBSD. But YP is the only one that can be accessed directly using standard C-library functions like getpwent(3), getgrent(3), gethostbyname(3) and so on. Thus, if you keep your data in a YP database, you do not need to copy it to local configuration files like master.passwd(5) before you can use it, for example to authenticate system users.
YP is a directory service compatible with Sun Microsystems NIS (Network Information System). See yp(8) for an overview of the available manual pages. Be careful, some operating systems contain directory services bearing similar names but all the same being incompatible, for example NIS+.
To use directory services other than YP, you either need to populate local
configuration files from the directory, or you need a YP frontend to
For example, you can use the
sysutils/login_ldap port when you
choose the former,
while the ypldap(8)
daemon provides the latter.
For some applications, simply synchronizing a small number of configuration
files among a group of machines using tools like
rsync (available from ports) constitutes an easy and robust
alternative to a full-blown directory service.
Thus, before setting up any YP server, you should consider whether these inherent security flaws are acceptable in your context. In particular, YP is inadequate if potential attackers have physical access to your network. Anybody gaining root access to any computer connected to your network segments carrying YP traffic can bind your YP domain and retrieve its data. In some cases, passing YP traffic through SSL or IPsec tunnels might be an option.
Use the domainname(1) utility to set the domain name, and put it into the defaultdomain(5) file to have it automatically set at system startup time.
# echo "puffynet" > /etc/defaultdomain # domainname `cat /etc/defaultdomain`Initialize the YP server using the interactive command:
# ypinit -mAt this point, it is not necessary to specify slave servers yet. To add slave servers, you can rerun ypinit(8) later, using the
-uoption. Setting up at least one slave server for each domain is useful to avoid service interruptions. For example, should the master server ever go down or lose network connectivity, client processes trying to access YP maps block indefinitely until they receive the requested information. Thus, YP service interruptions typically render the client hosts completely unusable until YP is back to service.
Decide where to store the source files to generate your YP maps from.
Keeping the server configuration separate from the served configuration
helps to control which information will be served and which won't, so the
/etc often isn't the best choice.
The only inconvenience caused by changing the source directory is that you will not be able to add, remove and modify users and groups in the YP domain using utilities like user(8) and group(8). Instead, you will have to edit the configuration files with a text editor.
To define the source directory, edit the file
and change the
DIR variable, e.g.
DIR=/etc/yp/src/puffynetConsider customizing other variables in
/var/yp/`domainname`/Makefile. See Makefile.yp(8) for details.
For example, even in case you use the default source directory
/etc, you do not usually need all accounts and groups existing
on the server on all your client hosts.
In particular, not serving the root account and thus keeping root's password
hash confidential is often beneficial to security.
Review the values of
MAXGID and adjust them to you needs.
If all your YP clients run OpenBSD or FreeBSD, exclude the encrypted
passwords from the
passwd maps by setting
The former practice of editing the template file
/var/yp/Makefile.yp is no longer recommended.
Changes to that file affect all domains initialized after the change, but
do not affect domains initialized before the change, so this is error-prone
You both risk that the intended changes do not take effect, and you risk to
forget about them and have them affect other domains later which they were
never intended for.
Create the source directory and populate it with the configuration files
to learn which YP maps require which source files.
For the format of the individual configuration files, refer to
and so on, and look at the examples in
Create the initial version of your YP maps using the commands
# cd /var/yp # makeDo not worry about error messages from yppush(8) right now. The YP server is not yet running.
YP uses rpc(3) (remote procedure calls) to communicate with clients, so it is necessary to enable portmap(8). To do so, use rcctl(8).
# rcctl enable portmap # rcctl start portmapConsider using either the securenet(5) or the ypserv.acl(5) security feature of the YP server daemon. But be aware that both of these only provide IP based access control. Thus, they only help as long as potential attackers have neither physical access to the hardware of the network segments carrying your YP traffic nor root access to any host connected to those network segments.
Finally, start the YP server daemon:
# rcctl enable ypserv # rcctl start ypservTo test the new server, consider making it its own client, following the instructions in the first part of the next section. In case you don't want the server to use its own maps, you can disable the client part after the test with the following commands:
# rcctl stop ypbind # rcctl disable ypbindRemember that each time you change a file sourced by a YP map, you must regenerate your YP maps.
# cd /var/yp # makeThis updates all database files in
/var/yp/`domainname`, with one exception: The file
ypservers.db, listing all YP master and slave servers associated with the domain, is created directly from
ypinit -mand modified exclusively by
ypinit -u. In case you accidentally delete it, run
ypinit -uto recreate it from scratch.
Like on the server, you must set the domain name and enable the portmapper:
# echo "puffynet" > /etc/defaultdomain # domainname `cat /etc/defaultdomain` # rcctl enable portmap # rcctl start portmapIt is recommended to provide a list of YP servers in the configuration file
/etc/yp/`domainname`. Otherwise, the YP client daemon will use network broadcasts to find YP servers for its domain. Explicitly specifying the servers is both more robust and marginally less open to attack. If you have not set up any slave servers, just put the host name of the master server into
Enable and start the YP client daemon, ypbind(8).
# rcctl enable ypbind # rcctl start ypbindIf all went well you should be able to query the YP server using ypcat(1) and see your passwd map returned.
# ypcat passwd bob:*:5001:5000:Bob Nuggets:/home/bob:/usr/local/bin/zsh ...Another useful tool for debugging your YP setup is ypmatch(1).
The second part of configuring a YP client involves editing local configuration files such that certain YP maps get used by various system facilities. Not all servers serve all standard maps supported by the operating system, some servers serve additional non-standard maps, and you are by no means compelled to use all those maps. Which of the available maps shall or shall not be used, and for which purposes they shall be used, is fully at the discretion of the client host's system administrator.
For a list of standard YP maps and their standard usage, see Makefile.yp(8).
If you want to include all user accounts from the YP domain, append the default YP marker to the master password file and rebuild the password database:
# echo '+:*::::::::' >> /etc/master.passwd # pwd_mkdb -p /etc/master.passwdFor details on selective inclusion and exclusion of user accounts, see passwd(5). To test whether inclusion actually works, use the id(1) utility.
If you want to include all groups from the YP domain, append the default YP marker to the group file:
# echo '+:*::' >> /etc/groupFor details on selective group inclusion, see group(5).