/etc/jail.conf documentation?

Ricky G ricky1252 at hotmail.com
Fri Oct 30 12:28:01 UTC 2015

 This is intended. I'm not sure if its fixed, however I found an odd bug awhile back where reusing a bridge for a vnet jail causes a high number of dropped packets. The more it is reused the more the dropped packets. After around 4 jail restarts there was about 60% packet loss. To resolve it, I found recreating the bridge fixed the issue. I also only use one vnet so this isn't a problem for me, of course you are correct that multiple vnets with this configuration will not work. Sorry for not making that clear before I posted.

Really need to stop using outlook. I hate how \n is not read correctly. =/

Date: Fri, 30 Oct 2015 08:17:59 +0000
Subject: Re: /etc/jail.conf documentation?
From: kraduk at gmail.com
To: ricky1252 at hotmail.com
CC: feld at freebsd.org; freebsd-questions at freebsd.org

Be careful with your vnet config as if you use it with more than one jail at once shutting down one jail will break the networking on the other(s) as you create and destroy the bridge. This may be intended but in most cases I suspect people bind a bridge to a physical NIC and the epairs for a flat network, with maybe a vlan or two thrown in. In these cases let cloned_interfaces build the bridge and just add and remove the nics to the relevant bridge(s).

On 29 October 2015 at 15:04, Ricky G <ricky1252 at hotmail.com> wrote:
Saw this post and decided to share as well. When I started using jails I wanted the system to be easy and flexible. Reading the handbook, I liked this layout https://www.freebsd.org/doc/handbook/jails-application.html. I decided to make some scripts based on this layout and I also made some improvements based on problems I ran into using the layout.

Basically the scripts create a readonly base and duplicates the base setting to readonly. Upgrading is simple because you just recreate the base shutdown duplicate startup and the jails are updated. One side note that Id like to add is my use of mergemaster is the safe way which is a bit more work. (The scripts will do everything except create the base dataset). I still have some more work to do on these scripts with possible errors, but they work well for what I need them for. As for my jail.conf

host.hostname = "${name}";path = "/usr/jails/${name}";mount.fstab = "/etc/fstab.${name}";mount.devfs = "1";devfs_ruleset = "4";exec.consolelog = "/var/log/jail_${name}_console.log";interface  = "ue0";exec.start  = "/bin/sh /etc/rc";exec.stop  = "/bin/sh /etc/rc.shutdown";exec.clean;persist;

allow.raw_sockets = "1";allow.set_hostname = "0";

foo { ip4.addr  = "";}

### For vnet ###bar { $if = "0"; $ip_addr  = ""; $ip_route  = ""; interface  = "bridge0"; vnet; vnet.interface = "epair${if}b"; exec.prestart  = "ifconfig bridge0 create"; exec.prestart  += "ifconfig epair${if} create up"; exec.prestart  += "ifconfig bridge0 addm epair${if}a"; exec.start  = "/sbin/ifconfig lo0 up"; exec.start  += "/sbin/ifconfig epair${if}b inet ${ip_addr} up"; exec.start  += "/sbin/route add default ${ip_route}"; exec.start  += "/bin/sh /etc/rc"; exec.stop  = "/bin/sh /etc/rc.shutdown"; exec.poststop  = "ifconfig bridge0 destroy"; exec.poststop  += "ifconfig epair${if}a destroy"; exec.clean; persist;}

$ cat update #!/usr/bin/env bashTEMPLATE_ZFS_DIR="tank/jails/template"TEMPLATE_NAME="main"TEMPLATE_DIR="/usr/jails/template"TEMPLATE_SNAPSHOT_NAME="now"JAIL_DIR="/usr/jails"JAIL_ZFS_DIR="tank/jails"JAILS=( $(jls | grep ${JAIL_DIR} | awk '{ print $3 }') )SRC="/usr/src"


### Some error checking ###zfs list "${ZFS_TEMPLATE}" >& /dev/nullif [ $? -eq 1 ];then  echo "Template dataset ${ZFS_TEMPLATE} not found, or wrong Template name"       exit 1fiif [ $(zfs get mountpoint "${ZFS_TEMPLATE}" | awk '{ print $3 }' | tail -n 1) != "${TEMPLATE}" ]then    echo "Template dataset not mounted at ${TEMPLATE}"      exit 1fiif [ $(zfs get mounted "${ZFS_TEMPLATE}" | awk '{ print $3 }' | tail -n 1) != yes ]then echo "Template dataset ${ZFS_TEMPLATE} not mounted"     exit 1fi### Destroy old template ###zfs set readonly=off "${ZFS_TEMPLATE}"chflags -R 0 "${TEMPLATE}"rm -r "${TEMPLATE}"/*cd "${SKEL}"rm -R media root etc mnt tmp var

### Create new template ###cd ${SRC}make installworld DESTDIR="${TEMPLATE}"if [ $? -eq 1 ]then  echo "${SRC} Needs to be compiled. Run make buildworld."        exit 1fimake distribution DESTDIR="${TEMPLATE}"

### Recreate skel ###cd "${TEMPLATE}"for skel in media root etc mnt tmp vardo   mv "${TEMPLATE}"/"${skel}" "${SKEL}"/done

if [ -f /etc/resolv.conf ]then  cp /etc/resolv.conf "${SKEL}"/etc/fiprintf 'hostname=""\nsendmail_enable="NO"\nsendmail_submit_enable="NO"\nsendmail_outbound_enable="NO"\nsendmail_msp_queue_enable="NO"' > "${SKEL}"/etc/rc.conf### Create links for new template ###for link in etc home mnt media root tmp vardo    ln -s s/${link} "${TEMPLATE}"/${link}doneln -s ../s/home "${TEMPLATE}"/usr/homeln -s ../s/usr-X11R6 "${TEMPLATE}"/usr/X11R6mkdir "${TEMPLATE}"/s

### Finish template by setting readonly=on ###zfs set readonly=on "${ZFS_TEMPLATE}"

### Move old template to a new name if it exists ###zfs list "${TEMPLATE_SNAPSHOT}" >& /dev/nullif [ $? -eq 0 ];then    zfs rename "${TEMPLATE_SNAPSHOT}" "${TEMPLATE_OLD_SNAPSHOT}"fi

### Create snapshot of the new template ###zfs snapshot "${TEMPLATE_SNAPSHOT}"### Updating jails that are currently running ###for jail in ${JAILS[@]};do       if [ $(jls | grep ${jail} | awk '{ print $4 }') == "${JAIL_DIR}"/"${jail}" ]    then            cd /usr/src             mergemaster -t "${JAIL_DIR}"/"${jail}"/var/tmp/temproot -D "${JAIL_DIR}"/"${jail}"/s -i -F              cd "${JAIL_DIR}"/"${jail}"/s            rm -r .cshrc .profile COPYRIGHT bin boot dev lib libexec proc rescue sbin sys usr               cd /usr/src             jail -r "${jail}"               zfs destroy -f "${JAIL_ZFS_DIR}"/"${jail}"              zfs clone -o readonly=on -o mountpoint="${JAIL_DIR}"/"${jail}" "${TEMPLATE_SNAPSHOT}" "${JAIL_ZFS_DIR}"/"${jail}"               jail -c "${jail}"       else            FAILED+="${jail} "      fidone

### Destroy old template ###zfs destroy "${TEMPLATE_OLD_SNAPSHOT}"if [ -n "${FAILED}" ]then     printf "The following jails failed to update due to incorrect mountpoint... ${FAILED}\n"fiecho "Update Finished"

$ cat duplicate #!/usr/bin/env bashTEMPLATE_ZFS_DIR="tank/jails/template"TEMPLATE_NAME="main"TEMPLATE_DIR="/usr/jails/template"TEMPLATE_SNAPSHOT_NAME="now"JAIL_DIR="/usr/jails"JAIL_ZFS_DIR="tank/jails"


echo What will the jail name be?read -e JAIL_NAMEecho What will the ip4 address be? ie -e IP4zfs list "${ZFS_TEMPLATE}" >& /dev/nullif [ $? -eq 1 ];then    echo "Incorrect template"       exit 1fizfs list "${TEMPLATE_SNAPSHOT}" >& /dev/nullif [ $? -eq 1 ];then        echo "Snapshot not found"       exit 1fi


zfs clone -o readonly=on -o mountpoint="${JAIL_FSTAB}" "${TEMPLATE_SNAPSHOT}" "${JAIL}"if [ $? -eq 1 ];then     echo "clone failed"     exit 1fiecho "clone successful"zfs create -o recordsize=1M -o compression=lz4 -o mountpoint="${JAIL_DATA}" "${JAIL_ZFS_DATA}"zfs create -o recordsize=1M -o compression=lz4 -o canmount=noauto "${JAIL_ZFS_DATA_LOCAL}"cp -Ra "${SKEL}"/* "${JAIL_DATA}"/umount "${JAIL_DATA}"rmdir "${JAIL_DATA}"zfs set canmount=noauto "${JAIL_ZFS_DATA}"printf "${JAIL_ZFS_DATA} ${JAIL_FSTAB}/s\tzfs\trw 0 0\n${JAIL_ZFS_DATA_LOCAL} ${JAIL_FSTAB}/usr/local\t zfs\trw 0 0" > /etc/fstab."${JAIL_NAME}"printf "\n${JAIL_NAME} {\n ip4.addr = \"${IP4}\";\n}" >> /etc/jail.conf


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