bcron is a better cron (though the “b” in the name probably comes from the first name of its writer, Bruce Guenter). It was created with security in mind, and is especially well suited for multi-user systems where the individual users need to be given access to their respective crontabs. With bcron this can be accomplished without compromising the system security. Here’s a quote from the bcron page:
This is bcron, a new cron system designed with secure operations in mind. To do this, the system is divided into several seperate programs, each responsible for a seperate task, with strictly controlled communications between them. The user interface is a drop-in replacement for similar systems (such as vixie-cron), but the internals differ greatly.
As of writing of this bcron can not be found in the FreeBSD 7.0 ports system. Fortunately its installation is fairly straightforward. Yet the included documentation is rather spartan so I provide a more complete outline below.
- Install latest bglibs if not yet installed** bglibs is best to install from a downloaded tarball rather than from the ports (while the ports version installs the libs in a more logical location at /usr/local/lib/bglibs/ the programs that utilize the library (bcron, ucspi-unix, etc.) have difficulty locating it.
** few symlinks are required (these refer to the locations bglibs installs itself when compiled from the tarball rather than from the ports):
/usr/local/bglibs -> /usr/local/lib/bglibs
/usr/local/bglibs/lib/libbg-sysdeps.so.2 -> /usr/local/lib/libbg-sysdeps.so.2
/usr/local/bglibs/lib/libbg.so.2 -> /usr/local/lib/libbg.so.2
- Install ucspi-unix if not yet installed as bcron components communicate via UNIX sockets. This requires bglibs and also compiles and installs well using a downloaded tarball (it’s also available in ports at /usr/ports/sysutils/ucspi-unix, but I prefer to compile it from the downloaded tarball).
- Make sure /var has been moved off the root to /usr/var before proceeding. See an older post for details.
- Make sure daemontools (and hence supervise) has been installed and is operational as bcron will be started with it.
- Create a system user “cron” (for example by using vipw command) and group “cron” (by editing /etc/group). This user/group will own all the crontab files (though not /etc/crontab as it’s system crontab and needs to be owned by root:wheel).
user:
cron:*:50:50::0:0:BCron Sandbox:/nonexistent:/usr/sbin/nologin
group:
cron:*:50:
- Create the spool & tmp directories:
mkdir -p /var/spool/cron/crontabs /var/spool/cron/tmp
mkfifo /var/spool/cron/trigger
sh
for i in crontabs tmp trigger; do
chown cron:cron /var/spool/cron/$i
chmod go-rwx /var/spool/cron/$i
done
- Create the configuration directory /usr/local/etc/bcron:mkdir -p /usr/local/etc/bcron** You can put any common configuration settings into this directory (it is an “ENVDIR”), like alternate spool directories in BCRON_SPOOL.
- Create the bcron service directories (there are three services) and add the scripts below it:
mkdir -p /var/bcron/supervise/bcron-sched/log
mkdir /var/bcron/supervise/bcron-spool
mkdir /var/bcron/supervise/bcron-update
Set their permissions to 1750 for security purposes (no world access, sticky bit):
chmod 1750 /var/bcron/supervise/bcron-sched
chmod 1750 /var/bcron/supervise/bcron-spool
chmod 1750 /var/bcron/supervise/bcron-update
Make all the run and log/run scripts executable by root, readable by group:
chmod 740 /var/bcron/supervise/bcron-sched/run
chmod 740 /var/bcron/supervise/bcron-sched/log/run
chmod 740 /var/bcron/supervise/bcron-spool/run
chmod 740 /var/bcron/supervise/bcron-update/run
and make log bcron-sched subdir accessible by root, group:
chmod 750 /var/bcron/supervise/bcron-sched/log
RUN SCRIPTS:
/var/bcron/supervise/bcron-sched/run:
#!/bin/sh
exec 2>&1
exec envdir /usr/local/etc/bcron bcron-start | multilog t /var/log/bcron
/var/bcron/supervise/bcron-sched/log/run:
#!/bin/sh
exec >/dev/null 2>&1
exec \
multilog t /var/log/bcron
/var/bcron/supervise/bcron-spool/run:
#!/bin/sh
exec >/dev/null 2>&1
exec \
envdir /usr/local/etc/bcron \
envuidgid cron \
sh -c ‘
exec \
unixserver -U ${BCRON_SOCKET:-/var/run/bcron-spool} \
bcron-spool
‘
/var/bcron/supervise/bcron-update/run:
#!/bin/sh
exec >/dev/null 2>&1
exec \
bcron-update /etc/crontab
- Kill the deafult cron daemon and add the following to rc.conf so it won’t restart on reboot:
#disable default cron; bcron is used instead (started by supervise)
cron_enable=”NO”
- Symlink bcron services’ primary supervise directories to under /var/service to start bcron services (you can also use svc-add command if you have installed supervise-scripts):
ln -s /var/bcron/supervise/bcron-sched /var/service/bcron-sched
ln -s /var/bcron/supervise/bcron-spool /var/service/bcron-spool
ln -s /var/bcron/supervise/bcron-update /var/service/bcron-update
- Set /etc/crontab permissions to 600, and make sure it’s owned by the root.
chmod 600 /etc/crontab
chown root:wheel /etc/crontab
** For other users the owner of the crontab file in their respective home folders would be cron:cron.
- Edit /etc/crontab and test that it gets updated. Note that there is a brief delay, perhaps one minute or so, after you save the crontab until the change becomes effective. Also note that the default shell for the crontab is /bin/sh. You might want to change it to something more powerful like c-shell (/bin/csh) or bash (/bin/bash) that you’re familiar with. You may also want to augment the default path, for example, by including /usr/local/bin for user-installed commands.
One one of the first things I do on a newly installed FreeBSD system is to move /var and /tmp to under /usr. Since I usually allocate about 4Gb for the root slice and the rest of a disk—usually several hundred gigabytes—goes to /usr (well, there’s also the swap slice that takes few gigabytes) having /var and /tmp there is more comfortable as some log files, database files, or some temp files can sometimes grow to multi-gigabyte size and exhaust the root space.
Below is a simple procedure to move the /var to /usr/var and /tmp to /usr/var/tmp. This is best to do early on in a new system installation since many services tend to hook into /tmp and/or /var, and may thus lock files in those directories making the move more difficult. If you’re making this move on an established system, at least stop all the services that might interfere with the process (such as database services). It might even be a good idea to boot into a single user mode (if you do so, remember to correctly mount your disks before proceeding). I usually do this early in a new system install, before installing any major services, or at least before scripting them to run.
- Move /var to /usr/var
mkdir /usr/var
cd /var
tar cvf - . | (cd /usr/var; tar xvf - )
cd /
chflags -R noschg /var
rm -rf /var
ln -s /usr/var /var
- Move /tmp to /usr/var/tmp
mkdir /usr/var/tmp
cd /tmp
tar cvf - . | (cd /usr/var/tmp; tar xvf - )
cd /
chflags -R noschg /tmp
rm -rf /tmp
ln -s /usr/var/tmp /tmp
chmod -h 777 /tmp
chmod 1777 /usr/var/tmp
Below is my FreeBSD 7.0 kernel configuration file. I created it on my reference system, to be used on four production servers whose hardware configurations differ some. For that reason there’re few options (indicated as “[OPTION]“) that are conditional for the configurations. I’ve also left in IPv6 options which are currently commented out, but that I may take into use later if/when IPv6 becomes more prevalent in the environment these servers operate.
Edit: Because Wordpress doesn’t allow the tabulated configuration file to be presented in a readable manner, rather than including the configuration file in this post I made it available as a separate text file.
I’ve been running various versions of FreeBSD since 2001, and over that time the installation procedure has changed several times as new versions of the operating system have been released. Since I’m jack of all trades (or at least many trades), often several months or more passes without significant work in the UNIX environment, and my memory fades as I’m engrossed in something completely different such as software development work. I’m still running FreeBSD 6.1 in production environments, but want to make the move to 7.0 soon. Before doing so, however, I decided to set up a reference system and document the setup process to avoid major surprises (or my own memory glitches) as I reinstall the OS on the production systems — and hopefully have as a result minimum downtime possible.
Step one… FreeBSD installation using the Custom install. I post my notes below; perhaps someone will find this useful. The system is being set up as a web/db/mail server that is administered remotely; no X11 is needed or desired.
- Use custom install w/defaults except..
Skip PCCARD: YES
Media Type: CDROM
- Set keymap if not ASCII (I use Finnish keyboard so I selected “Finnish ISO”) and timezone in post install.
- Old mount point & label info is ok (from the older installations). I use “4069M” for boot, “6100M” for swap, and rest for application data (generally a largish RAID-5 or RAID-6 array is used), the respective mount point labels are “/”, swap, and “/usr”. I use standard boot record since no other operating systems are installed on the system. Boot drive is made bootable, softupdates is enabled on the data slice.
- Configure network, system name, keyboard map (sysinstall should’ve created delta for it) in /etc/rc.conf. Much more should and will go into it, but the basics that will get the system online are:
keymap="finnish.iso" #obviously optional 
hostname="this.systemname.com"
defaultrouter="192.168.1.1"
ifconfig_em0="inet 192.168.1.99 netmask 255.255.255.0" #currently installing behind a firewall
fsck_y_enable="yes" #this is good to set in case your system crashes during setup without orderly shutdown.. you don't have to press "yes" a million times
Note that you may have a different kind of network interface and you might have to adjust the “ifconfig_em0 accordingly.
- Configure DNSes in /etc/resolv.conf. I use OpenDNS servers, like so:
domain this.systemname.com
nameserver 208.67.222.222
nameserver 208.67.220.220
- If you’re basing this installation on an older install, import your old .cshrc or the equivalent alias/setting file of your favorite shell (makes the life easier as aliases work, etc).
- If you’re not using X11, enter `WITHOUT_X11′ in /etc/make.conf so you don’t have to set it in the environment every time.
WITHOUT_X11=yes #don't compile GUI to ports apps
CPUTYPE=i686 #set this for modern Intel CPUs
KERNCONF=YOUR_KERNEL_CONF_FILE_NAME
OPENSSLBASE=/usr/local #obviously if you use OpenSSL
- Build /usr/ports/net/cvsup with WITHOUT_X11 set in make.conf (as above) or in the environment, or use /usr/ports/net/cvsup-without-gui/ and update the ports tree.First create /usr/local/etc/cvsup/supfile.ports containing:
*default host=cvsup12.FreeBSD.org
*default base=/usr/local/etc/cvsup
*default prefix=/usr
*default release=cvs tag=.
*default delete use-rel-suffix
ports-all
If you want to use the fastest cvs server available, install /usr/ports/sysutils/fastest_cvsup/ and run with fastest_cvsup -c us (replace ‘us’ with your local country code if you’re not in the U.S. :-)), then use the cvs server indicated as the default host. Then update ports with
/usr/local/bin/cvsup -g -L 2 /usr/local/etc/cvsup/supfile.ports
You can use an optional `-d 100′ to limit file deletions to 100 initially to make sure update is working and the entire ports tree won’t be wiped out. Then remove it for full run (intial run *will* need to delete more than 100 files, but they’re not all in sequence)
- Build & install /usr/ports/editors/joe (or whatever your favorite editor might be); this makes life easier as configuration progresses.
- Build & install /usr/ports/security/openssh-portable. Use defaults + select `Enable CHROOT support’ (for later use)
- Create a non-root user for remote login. vipw is an easy way to manage users.
- Configure OpenSSH daemon in /usr/local/etc/ssh/sshd_config & make sure sshd starts (set openssh_enable=”yes” in /etc/rc.conf, and make sure the start file is called /usr/local/etc/rc.d/openssh.sh; reboot may be required to create the necessary server keys & start the service (confirm with ps -waux | grep “ssh”).sshd_config params of note (for initial access) are..
AllowUsers root MyUserName
PermitRootLogin without-password #allow root login only with a RSA-key
PasswordAuthentication yes
UsePAM no
UseDNS no
** remote login should be possible at this point **
- Create /usr/local/etc/cvsup/supfile.sources with the below content, then update sources with /usr/local/bin/cvsup -g -L 2 /usr/local/etc/cvsup/supfile.sources
*default host=cvsup17.FreeBSD.org
*default base=/usr/local/etc/cvsup
*default prefix=/usr
*default release=cvs tag=RELENG_7_0
*default delete use-rel-suffix
src-all
doc-all
- Review kernel configuration at /usr/src/sys/i386/conf (see my kernel defaults in the next post).
- Build & install new world if any deltas were applied in source update:
cd /usr/src && make buildworld.
If there are problems, try the following, then run buildworld again.
cd /usr/obj
chflags -R noschg *
rm -rf *
When buildworld completes, reboot the system, select option 4, or interrupt the reboot (option 6) and type boot -s to boot into single user mode; accept /bin/sh as the shell, then continue with the following commands to install new world:
mount -u /
mount -a -t ufs
swapon -acd /usr/src
make installworld
exit (goes multi-user)
- Build custom kernel & install with below commands:
cd /usr/src
make cleandir
make buildkernel
- Make a backup copy of the old kernel and install the new:
cp -Rp /boot/kernel /boot/kernel.recent
make installkernel
- Reboot & confirm that the latest kernel version is running with uname -a (or uname -rs).
- Make a copy of the functional kernel if boot is ok:chflags -R noschg /boot/kernel && cp -Rp /boot/kernel /boot/kernel.save && chflags -R schg /boot/kernel
- Set /boot/loader.conf parameters, like so:
kern.ipc.nmbclusters=16384 # Set the number of mbuf clusters
kern.ipc.maxsockets=16384 # Set the number of tcp sockets
kern.ipc.maxpipekva=67108864
kern.maxusers=128
Basic install & kernel setup is now complete.