stoney backup: Server set-up

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Abstract

This document describes server setup for the stoney cloud (Online) Backup service, built upon the Gentoo Linux distribution.

Overview

After working through this documentation, you will be able to set up and configure your own (Online) Backup service server.

Software Installation

Requirements

A working stoney cloud installation.

USE-Flages

For a full OpenLDAP directory installation:

echo "net-nds/openldap overlays perl sasl" >> /etc/portage/package.use

For a minimal OpenLDAP directory installation (just the necessary tools):

echo "sys-auth/nss-pam-ldapd sasl" >> /etc/portage/package.use
echo "sys-auth/nss-pam-ldapd ~amd64" >> /etc/portage/package.keywords
echo "net-nds/openldap ~amd64" >> /etc/portage/package.keywords
echo "sys-fs/quota ldap" >> /etc/portage/package.use

For the prov-backup-rsnapshot daemon

echo "dev-perl/Net-SMTPS ~amd64" >> /etc/portage/package.keywords
echo "perl-core/Switch ~amd64" >> /etc/portage/package.keywords

Emerge

emerge ⁻va nss-pam-ldapd
emerge -va rsnapshot
emerge -va quota
emerge -va dev-perl/Config-IniFiles
emerge -va dev-perl/LockFile-Simple
emerge -va dev-perl/Net-SMTPS
emerge -va dev-perl/perl-ldap
emerge -va virtual/perl-Switch
emerge -va dev-perl/Parallel-ForkManager
emerge -va dev-perl/XML-Simple
emerge -va dev-perl/Date-Calc
emerge -va dev-perl/DateManip
emerge -va dev-perl/DateTime-Format-Strptime
emerge -va dev-perl/text-template
emerge -va perl-core/Switch

CPAN

Install the Time::Stopwatch, XML::Validator::Schema and Schedule::Cron::Events lib form CPAN (no ebuild available)

cpan
cpan[1]> install Time::Stopwatch
  LWP not available
Fetching with Net::FTP:
ftp://tux.rainside.sk/CPAN/authors/01mailrc.txt.gz
Going to read '/root/.cpan/sources/authors/01mailrc.txt.gz'
...
  ILTZU/Time-Stopwatch-1.00.tar.gz
  /usr/bin/make install  -- OK

cpan[2]> install XML::Validator::Schema
Going to read '/root/.cpan/Metadata'
...
  SAMTREGAR/XML-Validator-Schema-1.10.tar.gz
  /usr/bin/make install  -- OK

cpan[3]> install Schedule::Cron::Events
Going to read '/root/.cpan/Metadata'
...
  /usr/bin/make install  -- OK

cpan[4]> exit
Terminal does not support GetHistory.
Lockfile removed.

Software Configuration

Quota

32-bit Project Identifier Support

We need to enable 32-bit project identifier support (PROJID32BIT feature) for our naming scheme (uid numbers larger than 65'536):

mkfs.xfs -i projid32bit=1 /dev/vdb1

Mount

Make sure, that you have user quota (uqota) and project quota (pquota) set as options on the chosen mount point in /etc/fstab. For example:

/dev/vdb1               /var/backup     xfs             noatime,uquota,pquota   0 0

Verify

Remount the file system /var/backup and check, if /var/backup has the desired values:

xfs_quota -x -c state /var/backup

As you can see (items marked bold), we have achieved our goal:

User quota state on /var/backup (/dev/vdb1)
  Accounting: '''ON'''
  Enforcement: '''ON'''
  Inode: #131 (3 blocks, 2 extents)
Group quota state on /var/backup (/dev/vdb1)
  Accounting: OFF
  Enforcement: OFF
  Inode: #809717 (1 blocks, 1 extents)
Project quota state on /var/backup (/dev/vdb1)
  Accounting: '''ON'''
  Enforcement: '''ON'''
  Inode: #809717 (1 blocks, 1 extents)
Blocks grace time: [7 days 00:00:30]
Inodes grace time: [7 days 00:00:30]
Realtime Blocks grace time: [7 days 00:00:30]

User Quotas

Set a quota of 1 Gigabyte for the user 4000187 (the values are in kilobytes, so 1048576 kilobyte are 1024 megabytes which corresponds to 1 gigabyte):

/usr/sbin/setquota -u 4000187 0 1048576 0 0 /var/backup

Read the quota information for the user 4000187:

quota -uv 4000187
Disk quotas for user 4000187 (uid 4000187): 
     Filesystem  blocks   quota   limit   grace   files   quota   limit   grace
      /dev/vdb1       0       0 1048576               0       0       0 

Using xfs_quota gives us a nicer result:

xfs_quota -x -c 'quota -v -N -u 4000187' /var/backup
/dev/vdb1                    0          0    1048576   00 [--------] /var/backup

If the user has data in the project, that belongs to him, the result will change:

/dev/vdb1               512000          0    1048576   00 [--------] /var/backup

Project (Directory) Quotas

The XFS file system additionally allows you to set quotas on individual directory hierarchies in the file system that are known as managed trees. Each managed tree is uniquely identified by a project ID and an optional project name. We'll use the following values in the examples:

  • project_ID: The uid of the online backup account (4000187).
  • project_name: The uid of the online backup account (4000187). This could be a human readable name.
  • mountpoint: The mountpoint of the xfs-filesystem (/var/backup). See the /etc/fstab entry from above.
  • directory: The directory of the project (187/4000187), starting from the mountpoint of the xfs-filesystem (/var/backup).

Define a unique project ID for the directory hierarchy in the /etc/projects file (project_ID:mountpoint/directory):

echo "4000187:/var/backup/187/4000187" >> /etc/projects

Create an entry in the /etc/projid file that maps a project name to the project ID (project_name:project_ID):

echo "4000187:4000187" >> /etc/projid

Set Project:

xfs_quota -x -c 'project -s -p /var/backup/187/4000187 4000187' /var/backup

Check Project:

xfs_quota -x -c 'limit -p bhard=1048576k 4000187' /var/backup

Set Limit

xfs_quota -x -c 'quota -p 4000187' /var/backup

Check the Quota:

  • -v : increase verbosity in reporting (also dumps zero values).
  • -N : suppress the initial header.
  • -p : display project quota information.
xfs_quota -x -c 'quota -v -N -p 4000187' /var/backup
/dev/vdb1                    0          0    1048576   00 [--------] /var/backup

If you copied data into the project, the output will look something like:

/dev/vdb1               512000          0    1048576   00 [--------] /var/backup

To give you an overall view of the whole system:

xfs_quota -x -c report /var/backup
User quota on /var/backup (/dev/vdb1)
                               Blocks                     
User ID          Used       Soft       Hard    Warn/Grace     
---------- -------------------------------------------------- 
root          1024000          0          0     00 [--------]
4000187             0          0    1048576     00 [--------]

Project quota on /var/backup (/dev/vdb1)
                               Blocks                     
Project ID       Used       Soft       Hard    Warn/Grace     
---------- -------------------------------------------------- 
4000187        512000          0    1048576     00 [--------]

Some important notes concerning XFS

  1. The quotacheck command has no effect on XFS filesystems. The first time quota accounting is turned on (at mount time), XFS does an automatic quotacheck internally; afterwards, the quota system will always be completely consistent until quotas are manually turned off.
  2. There is no need for quota file(s) in the root of the XFS filesystem.

OpenSSH

Configure the OpenSSH daemon:

vi /etc/ssh/sshd_config

Set following options:

PubkeyAuthentication yes
PasswordAuthentication yes
UsePAM yes
Subsystem     sftp   internal-sftp

Make sure, that Subsystem sftp internal-sftp is the last line in the configuration file.

We want to reduce the numbers of chroot environments in one folder. As the ChrootDirectory configuration option only allows %h (home directory of the user) and %u (username of the user), we need to create the necessary matching rules in the form of:

Match User *000
  ChrootDirectory /var/backup/000/%u
Match
Match User *001
  ChrootDirectory /var/backup/001/%u
Match
...
Match User *999
  ChrootDirectory /var/backup/999/%u
Match

The creation of the matching rules is done by executing the following bash commands:

FILE=/etc/ssh/sshd_config;
 
for ((x=0; x<1000; x+=1)); \
do \
  printf "Match User *%03d\n" $x >> ${FILE}; \
  printf "  ChrootDirectory /var/backup/%03d/%%u\n" $x >> ${FILE}; \
  printf "Match\n" >> ${FILE}; \
done

Don't forget to restart the OpenSSH daemon:

/etc/init.d/sshd restart

OpenLDAP

/etc/openldap/ldap.conf

nss-pam-ldapd

/etc/nslcd.conf
# This is the configuration file for the LDAP nameservice
# switch library's nslcd daemon. It configures the mapping
# between NSS names (see /etc/nsswitch.conf) and LDAP
# information in the directory.
# See the manual page nslcd.conf(5) for more information.

# The user and group nslcd should run as.
uid nslcd
gid nslcd

# The uri pointing to the LDAP server to use for name lookups.
# Multiple entries may be specified. The address that is used
# here should be resolvable without using LDAP (obviously).
#uri ldap://127.0.0.1/
#uri ldaps://127.0.0.1/
#uri ldapi://%2fvar%2frun%2fldapi_sock/
# Note: %2f encodes the '/' used as directory separator
uri ldaps://ldapm.tombstone.ch

# The LDAP version to use (defaults to 3
# if supported by client library)
#ldap_version 3

# The distinguished name of the search base.
base dc=stoney-cloud,dc=org

# The distinguished name to bind to the server with.
# Optional: default is to bind anonymously.
binddn cn=Manager,dc=stoney-cloud,dc=org

# The credentials to bind with.
# Optional: default is no credentials.
# Note that if you set a bindpw you should check the permissions of this file.
bindpw myverysecretpassword

# The distinguished name to perform password modifications by root by.
#rootpwmoddn cn=admin,dc=example,dc=com

# The default search scope.
#scope sub
#scope one
#scope base

# Customize certain database lookups.
#base   group  ou=Groups,dc=example,dc=com
base   group  ou=groups,ou=backup,ou=services,dc=stoney-cloud,dc=org
base   passwd ou=accounts,ou=backup,ou=services,dc=stoney-cloud,dc=org
base   shadow ou=accounts,ou=backup,ou=services,dc=stoney-cloud,dc=org
#scope  group  onelevel
#scope  hosts  sub

#filter group  (&(objectClass=posixGroup)(sstIsActive=TRUE))
filter passwd (&(objectClass=posixAccount)(sstIsActive=TRUE))
filter shadow (&(objectClass=shadowAccount)(sstIsActive=TRUE))

# Bind/connect timelimit.
#bind_timelimit 30

# Search timelimit.
#timelimit 30

# Idle timelimit. nslcd will close connections if the
# server has not been contacted for the number of seconds.
#idle_timelimit 3600

# Use StartTLS without verifying the server certificate.
#ssl start_tls
tls_reqcert never

# CA certificates for server certificate verification
#tls_cacertdir /etc/ssl/certs
#tls_cacertfile /etc/ssl/ca.cert

# Seed the PRNG if /dev/urandom is not provided
#tls_randfile /var/run/egd-pool

# SSL cipher suite
# See man ciphers for syntax
#tls_ciphers TLSv1

# Client certificate and key
# Use these, if your server requires client authentication.
#tls_cert
#tls_key

# Mappings for Services for UNIX 3.5
#filter passwd (objectClass=User)
#map    passwd uid              msSFU30Name
#map    passwd userPassword     msSFU30Password
#map    passwd homeDirectory    msSFU30HomeDirectory
#map    passwd homeDirectory    msSFUHomeDirectory
#filter shadow (objectClass=User)
#map    shadow uid              msSFU30Name
#map    shadow userPassword     msSFU30Password
#filter group  (objectClass=Group)
#map    group  member           msSFU30PosixMember

# Mappings for Services for UNIX 2.0
#filter passwd (objectClass=User)
#map    passwd uid              msSFUName
#map    passwd userPassword     msSFUPassword
#map    passwd homeDirectory    msSFUHomeDirectory
#map    passwd gecos            msSFUName
#filter shadow (objectClass=User)
#map    shadow uid              msSFUName
#map    shadow userPassword     msSFUPassword
#map    shadow shadowLastChange pwdLastSet
#filter group  (objectClass=Group)
#map    group  member           posixMember

# Mappings for Active Directory
#pagesize 1000
#referrals off
#idle_timelimit 800
#filter passwd (&(objectClass=user)(!(objectClass=computer))(uidNumber=*)(unixHomeDirectory=*))
#map    passwd uid              sAMAccountName
#map    passwd homeDirectory    unixHomeDirectory
#map    passwd gecos            displayName
#filter shadow (&(objectClass=user)(!(objectClass=computer))(uidNumber=*)(unixHomeDirectory=*))
#map    shadow uid              sAMAccountName
#map    shadow shadowLastChange pwdLastSet
#filter group  (objectClass=group)

# Alternative mappings for Active Directory
# (replace the SIDs in the objectSid mappings with the value for your domain)
#pagesize 1000
#referrals off
#idle_timelimit 800
#filter passwd (&(objectClass=user)(objectClass=person)(!(objectClass=computer)))
#map    passwd uid           cn
#map    passwd uidNumber     objectSid:S-1-5-21-3623811015-3361044348-30300820
#map    passwd gidNumber     objectSid:S-1-5-21-3623811015-3361044348-30300820
#map    passwd homeDirectory "/home/$cn"
#map    passwd gecos         displayName
#map    passwd loginShell    "/bin/bash"
#filter group (|(objectClass=group)(objectClass=person))
#map    group gidNumber      objectSid:S-1-5-21-3623811015-3361044348-30300820

# Mappings for AIX SecureWay
#filter passwd (objectClass=aixAccount)
#map    passwd uid              userName
#map    passwd userPassword     passwordChar
#map    passwd uidNumber        uid
#map    passwd gidNumber        gid
#filter group  (objectClass=aixAccessGroup)
#map    group  cn               groupName
#map    group  gidNumber        gid


/etc/nsswitch.conf
passwd:      files ldap
shadow:      files ldap
group:       files ldap

# passwd:    db files nis
# shadow:    db files nis
# group:     db files nis

hosts:       files dns
networks:    files dns

services:    db files
protocols:   db files
rpc:         db files
ethers:      db files
netmasks:    files
netgroup:    files
bootparams:  files

automount:   files
aliases:     files

system-auth

vi /etc/pam.d/system-auth
auth        required    pam_env.so
auth      sufficient  pam_unix.so try_first_pass likeauth nullok
auth      sufficient  pam_ldap.so minimum_uid=1000 use_first_pass
auth      required pam_deny.so

account   sufficient  pam_ldap.so minimum_uid=1000
account     required    pam_unix.so
account   sufficient  pam_ldap.so minimum_uid=1000

password  sufficient    pam_unix.so try_first_pass  nullok sha512 shadow
password  sufficient  pam_ldap.so minimum_uid=1000 try_first_pass
password   required     pam_deny.so

session     required    pam_limits.so
session     required    pam_env.so
session     required    pam_unix.so
session   optional    pam_ldap.so minimum_uid=1000

sshd_config

vi /etc/ssh/sshd_config

Changes:

PasswordAuthentication yes
UsePAM yes
#AllowUsers

rsnapshot

Install the source

cd /var/work
git clone --recursive https://github.com/stepping-stone/backup-util.git
cd backup-util/bin
ln -s ../perl-utils/lib/PerlUtil/ PerlUtil

Configuration

vi /var/work/backup-util/etc/snapshot.conf 
[General]
MaxParallelProcesses = 5
Rsnapshot_command = /usr/bin/nice -n 19 /usr/bin/rsnapshot  -c /etc/rsnapshot/rsnapshot.conf.%uid% %interval%

[LDAP]
Host = ldaps://ldapm.tombstone.ch
Port = 636
User = cn=Manager,dc=foss-cloud,dc=org
Password = <Password>
CA_Path = /etc/ssl/certs
Accounts_Base = ou=accounts,ou=backup,ou=services,dc=foss-cloud,dc=org

Cronjobs

crontab -e
...
# Rsnapshot for all users
30 22 * * * /var/work/backup-util/bin/snapshot.pl --interval daily
15 22 * * sun /var/work/backup-util/bin/snapshot.pl --interval weekly
00 22 1 * * /var/work/backup-util/bin/snapshot.pl --interval monthly
...

prov-backup-rsnapshot

cd /var/work
git clone --recursive https://github.com/stepping-stone/prov-backup-rsnapshot.git
cd /var/work/prov-backup-rsnapshot/Provisioning/etc/Provisioning/
ln -s ../../../etc/Provisioning/Backup/ Backup
cd /var/work/prov-backup-rsnapshot/Provisioning/lib/Provisioning/
ln -s ../../../lib/Provisioning/Backup/ Backup
chmod -R a+rX /var/work

Configuration

The configuration file is currently located in the /var/work/prov-backup-rsnapshot directory:

vi /var/work/prov-backup-rsnapshot/etc/Provisioning/Backup/Rsnapshot_test.conf
# Copyright (C) 2013 stepping stone GmbH
#                    Switzerland
#                    http://www.stepping-stone.ch
#                    support@stepping-stone.ch
#
# Authors:
#  Pat Kläy <pat.klaey@stepping-stone.ch>
#  
# Licensed under the EUPL, Version 1.1.
#
# You may not use this work except in compliance with the
# Licence.
# You may obtain a copy of the Licence at:
#
# http://www.osor.eu/eupl
#
# Unless required by applicable law or agreed to in
# writing, software distributed under the Licence is
# distributed on an "AS IS" basis,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
# express or implied.
# See the Licence for the specific language governing
# permissions and limitations under the Licence.
#


[Global]
# If true the script logs every information to the log-file.
LOG_DEBUG = 1

# If true the script logs additional information to the log-file.
LOG_INFO = 1

#If true the script logs warnings to the log-file.
LOG_WARNING = 1

#If true the script logs errors to the log-file.
LOG_ERR = 1

ENVIRONMENT = 
 
[Database]
BACKEND = LDAP
SERVER = ldaps://ldapm.tombstone.ch
PORT = 636
ADMIN_USER = cn=Manager,dc=stoney-cloud,dc=org
ADMIN_PASSWORD = <PASSWORD>
SERVICE_SUBTREE = ou=accounts,ou=backup,ou=services,dc=stoney-cloud,dc=org
COOKIE_FILE = /var/work/prov-backup-rsnapshot/Provisioning/etc/Provisioning/Backup/rnsapshot.cookie
DEFAULT_COOKIE = rid=001,csn=
SEARCH_FILTER = (&(entryCSN>=%entryCSN%)(objectClass=*))

[Service]
MODUS = selfcare
TRANSPORTAPI = LocalCLI
SERVICE = Backup
TYPE = Rsnapshot

SYSLOG = Backup-Rsnapshot

[Gateway]
HOST = localhost
USER = provisioning
DSA_FILE = none

[Backup]
RSNAPSHOT_CONFIG_FILE = /etc/rsnapshot/rsnapshot.conf.%uid%
SET_QUOTA_CMD = /usr/sbin/setquota
CREATE_CHROOT_CMD = /root/createDummyBackupDirectory.sh # You might want to change this for the productive system
MOUNTPOINT = / # You might want to change this for the productive system

Init Scirpts

Currently we just create very basic init scripts which start and stop the deamon:

/etc/init.d/prov-backup-rsnapshot
#!/sbin/runscript
# Copyright 1999-2013 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Header: $

depend() {
    need net
    after slapd
}

start() {
    ebegin "Starting backup-rsnapshot provisioning daemon"
    start-stop-daemon --start \
        --background \
        --user ${USER:-root}:${GROUP:-root} \
        --make-pidfile \
        --pidfile "${PIDFILE}" \
        --exec /var/work/prov-backup-rsnapshot/Provisioning/bin/provisioning.pl \
        --interpreted \
        -- ${OPTIONS} \
            -c /var/work/prov-backup-rsnapshot/Provisioning/etc/Provisioning/Backup/Rsnapshot_test.conf \
            -g /var/work/prov-backup-rsnapshot/Provisioning/etc/Provisioning/Global.conf
    eend $?
}

stop() {
    ebegin "Stopping backup-rsnapshot provisioning daemon"
    start-stop-daemon --stop \
        --pidfile "${PIDFILE}"
    eend $?
}
/etc/conf.d/prov-backup-rsnapshot
USER="root"
GROUP="root"

PIDFILE="/run/prov-backup-rsnapshot.pid"

# OPTIONS="..."

Run-Level

rc-update add prov-backup-rsnapshot default

schedule warning

To install the new schedule warning script you have to execute the following commands:

cd /var/work/
git clone --recursive https://github.com/stepping-stone/backup-surveillance.git
cd backup-surveillance/bin/
ln -s ../perl-utils/lib/PerlUtil/ PerlUtil

Configuration

vi /var/work/backup-surveillance/etc/config.conf
[XML]
SCHEDULE_FILE = %homeDirectory%/incoming/%computerName%/.sepiola_backup/scheduler.xml
SCHEDULE_XSD = %configpath%/../etc/schema/scheduler_schema.xsd
BACKUP_ENDED_FILE = %homeDirectory%/incoming/%computerName%/.sepiola_backup/backupEnded.xml
BACKUP_ENDED_XSD =  %configpath%/../etc/schema/backupended_schema.xsd
BACKUP_STARTED_FILE = %homeDirectory%/incoming/%computerName%/.sepiola_backup/backupStarted.xml
BACKUP_STARTED_XSD =   %configpath%/../etc/schema/backupstarted_schema.xsd


[TEMPLATE]
Salutation_Default_de-CH = Liebe Kundin / Lieber Kunde
Salutation_m_de-CH = Sehr geehrter Herr
Salutation_f_de-CH = Sehr geehrte Frau
Salutation_Default_en-GB = Dear customer
Salutation_m_en-GB = Dear Mr.
Salutation_f_en-GB = Dear Mrs.

[LDAP]

SERVER = ldaps://ldapm.tombstone.ch
PORT = 636
DEBUG = 1

ADMIN_DN = cn=Manager,dc=foss-cloud,dc=org 
ADMIN_PASSWORD = <Password>

BACKUP_BASE = ou=accounts,ou=backup,ou=services,dc=foss-cloud,dc=org
PEOPLE_BASE = ou=people,dc=foss-cloud,dc=org
RESELLER_BASE = ou=reseller,ou=configuration,ou=backup,ou=services,dc=foss-cloud,dc=org
SCOPE = sub

[MAIL]
mailTo = 
host = mail.stepping-stone.ch
port = 587
username = 
password = 
from = 

writeAccountSize

If you have already installed the rsnapshot script, you also have the writeAccountSize script. Otherwise follow these instructions (installation only)

Configuration

vi /var/work/backup-util/etc/writeAccountSize.conf 
[Global]
INCOMING_DIRECTORY = /incoming
ACCOUNT_SIZE_FILE = /etc/backupSize
SNAPSHOTS = 1

[Syslog]
SYSLOG = rsnapshot

[Directory]
LDAP_SERVER = ldaps://ldapm.tombstone.ch
LDAP_PORT = 636
LDAP_BIND_DN = cn=Manager,dc=foss-cloud,dc=org
LDAP_BIND_PW = <password>
LDAP_BASE_DN = ou=accounts,ou=backup,ou=services,dc=foss-cloud,dc=org
LDAP_PERSON_BASE = ou=people,dc=foss-cloud,dc=org
LDAP_RESELLER_BASE = ou=reseller,ou=configuration,ou=backup,ou=services,dc=foss-cloud,dc=org
LDAP_EMAIL_ATTRIBUTE = mail

[Notification]
EMAIL_SENDER = stepping stone GmbH Supprt <support@stepping-stone.ch>
EMAIL_ALERT_THRESHOLD = 85

Salutation_Default_de-CH = Liebe Kundin / Lieber Kunde
Salutation_m_de-CH = Sehr geehrter Herr
Salutation_f_de-CH = Sehr geehrte Frau
Salutation_Default_en-GB = Dear customer
Salutation_m_en-GB = Dear Mr.
Salutation_f_en-GB = Dear Mrs.

[MAIL]
host = mail.stepping-stone.ch
port = 587
username = support@stepping-stone.ch
password = <password>

Links

  • OpenLDAP, an open source implementation of the Lightweight Directory Access Protocol.
  • nss-pam-ldapd, a Name Service Switch (NSS) module that allows your LDAP server to provide user account, group, host name, alias, netgroup, and basically any other information that you would normally get from /etc flat files or NIS.
  • Gentoo Leitfaden zur OpenLDAP Authentifikation.
  • Centralized authentication using OpenLDAP.
  • openssh-lpk_openldap.schema OpenSSH LDAP Public Keys.
  • linuxquota Linux DiskQuota.
  • rsnapshot, a remote filesystem snapshot utility, based on rsync.
  • Jailkit, set of utilities to limit user accounts to specific files using chroot() and or specific commands. Also includes a tool to build a chroot environment.
  • Busybox BusyBox combines tiny versions of many common UNIX utilities into a single small executable. Useful to reduce the number of files (and thus the complexity) when building a chroot.