DOKK / manpages / debian 10 / firejail / firejail.1.en
FIREJAIL(1) firejail man page FIREJAIL(1)

Firejail - Linux namespaces sandbox program

Start a sandbox:

firejail [OPTIONS] [program and arguments]

File transfer from an existing sandbox

firejail {--ls | --get | --put} dir_or_filename

Network traffic shaping for an existing sandbox:

firejail --bandwidth={name|pid} bandwidth-command

Monitoring:

firejail {--list | --netstats | --top | --tree}

Miscellaneous:

firejail {-? | --debug-caps | --debug-errnos | --debug-syscalls | --debug-protocols | --help | --version}

Firejail is a SUID sandbox program that reduces the risk of security breaches by restricting the running environment of untrusted applications using Linux namespaces, seccomp-bpf and Linux capabilities. It allows a process and all its descendants to have their own private view of the globally shared kernel resources, such as the network stack, process table, mount table. Firejail can work in a SELinux or AppArmor environment, and it is integrated with Linux Control Groups.

Written in C with virtually no dependencies, the software runs on any Linux computer with a 3.x kernel version or newer. It can sandbox any type of processes: servers, graphical applications, and even user login sessions.

Firejail allows the user to manage application security using security profiles. Each profile defines a set of permissions for a specific application or group of applications. The software includes security profiles for a number of more common Linux programs, such as Mozilla Firefox, Chromium, VLC, Transmission etc.

Without any options, the sandbox consists of a filesystem build in a new mount namespace, and new PID and UTS namespaces. IPC, network and user namespaces can be added using the command line options. The default Firejail filesystem is based on the host filesystem with the main system directories mounted read-only. These directories are /etc, /var, /usr, /bin, /sbin, /lib, /lib32, /libx32 and /lib64. Only /home and /tmp are writable.

As it starts up, Firejail tries to find a security profile based on the name of the application. If an appropriate profile is not found, Firejail will use a default profile. The default profile is quite restrictive. In case the application doesn't work, use --noprofile option to disable it. For more information, please see SECURITY PROFILES section below.

If a program argument is not specified, Firejail starts /bin/bash shell. Examples:

$ firejail [OPTIONS] # starting a /bin/bash shell

$ firejail [OPTIONS] firefox # starting Mozilla Firefox

# sudo firejail [OPTIONS] /etc/init.d/nginx start

--
Signal the end of options and disables further option processing.
Allow tools such as strace and gdb inside the sandbox by whitelisting system calls ptrace and process_vm_readv. This option is only available when running on Linux kernels 4.8 or newer - a kernel bug in ptrace system call allows a full bypass of the seccomp filter.

Example:
$ firejail --allow-debuggers --profile=/etc/firejail/firefox.profile strace -f firefox

All directories under /home are visible inside the sandbox. By default, only current user home directory is visible.

Example:
$ firejail --allusers

Enable AppArmor confinement. For more information, please see APPARMOR section below.
Sandbox an AppImage (https://appimage.org/) application. If the sandbox is started as a regular user, nonewprivs and a default capabilities filter are enabled.

Example:
$ firejail --appimage krita-3.0-x86_64.appimage
$ firejail --appimage --private krita-3.0-x86_64.appimage
$ firejail --appimage --net=none --x11 krita-3.0-x86_64.appimage

Print the AppArmor confinement status for the sandbox identified by name or by PID.

Example:
$ firejail --apparmor.print=browser
5074:netblue:/usr/bin/firejail /usr/bin/firefox-esr
AppArmor: firejail-default enforce

Audit the sandbox, see AUDIT section for more details.
Audit the sandbox, see AUDIT section for more details.
Set bandwidth limits for the sandbox identified by name or PID, see TRAFFIC SHAPING section for more details.
Mount-bind filename1 on top of filename2. This option is only available when running as root.

Example:
# firejail --bind=/config/etc/passwd,/etc/passwd

Blacklist directory or file. File globbing is supported, see FILE GLOBBING section for more details.

Example:
$ firejail --blacklist=/sbin --blacklist=/usr/sbin
$ firejail --blacklist=~/.mozilla
$ firejail "--blacklist=/home/username/My Virtual Machines"
$ firejail --blacklist=/home/username/My\ Virtual\ Machines

The command builds a whitelisted profile. The profile is printed on the screen. If /usr/bin/strace is installed on the system, it also builds a whitelisted seccomp profile. The program is run in a very relaxed sandbox, with only --caps.drop=all and --nonewprivs. Programs that raise user privileges are not supported in order to allow strace to run. Chromium and Chromium-based browsers will not work.

Example:
$ firejail --build vlc ~/Videos/test.mp4

The command builds a whitelisted profile, and saves it in profile-file. If /usr/bin/strace is installed on the system, it also builds a whitelisted seccomp profile. The program is run in a very relaxed sandbox, with only --caps.drop=all and --nonewprivs. Programs that raise user privileges are not supported in order to allow strace to run. Chromium and Chromium-based browsers will not work.

Example:
$ firejail --build=vlc.profile vlc ~/Videos/test.mp4

Login shell compatibility option. This option is use by some login programs when executing the login shell, such as when firejail is used as a restricted login shell. It currently does not change the execution of firejail.
Linux capabilities is a kernel feature designed to split up the root privilege into a set of distinct privileges. These privileges can be enabled or disabled independently, thus restricting what a process running as root can do in the system.

By default root programs run with all capabilities enabled. --caps option disables the following capabilities: CAP_SYS_MODULE, CAP_SYS_RAWIO, CAP_SYS_BOOT, CAP_SYS_NICE, CAP_SYS_TTY_CONFIG, CAP_SYSLOG, CAP_MKNOD, CAP_SYS_ADMIN. The filter is applied to all processes started in the sandbox.

Example:
$ sudo firejail --caps /etc/init.d/nginx start

Drop all capabilities for the processes running in the sandbox. This option is recommended for running GUI programs or any other program that doesn't require root privileges. It is a must-have option for sandboxing untrusted programs installed from unofficial sources - such as games, Java programs, etc.

Example:
$ firejail --caps.drop=all warzone2100

Define a custom blacklist Linux capabilities filter.

Example:
$ firejail --caps.drop=net_broadcast,net_admin,net_raw

Define a custom whitelist Linux capabilities filter.

Example:
$ sudo firejail --caps.keep=chown,net_bind_service,setgid,\ setuid /etc/init.d/nginx start

Print the caps filter for the sandbox identified by name or by PID.

Example:
$ firejail --name=mygame --caps.drop=all warzone2100 &
$ firejail --caps.print=mygame

Example:
$ firejail --list
3272:netblue::firejail --private firefox
$ firejail --caps.print=3272

Place the sandbox in the specified control group. tasks-file is the full path of cgroup tasks file.

Example:
# firejail --cgroup=/sys/fs/cgroup/g1/tasks

Chroot the sandbox into a root filesystem. Unlike the regular filesystem container, the system directories are mounted read-write. If the sandbox is started as a regular user, nonewprivs and a default capabilities filter are enabled.

Example:
$ firejail --chroot=/media/ubuntu warzone2100

Set CPU affinity.

Example:
$ firejail --cpu=0,1 handbrake

Print the CPU cores in use by the sandbox identified by name or by PID.

Example:
$ firejail --name=mygame --caps.drop=all warzone2100 &
$ firejail --cpu.print=mygame

Example:
$ firejail --list
3272:netblue::firejail --private firefox
$ firejail --cpu.print=3272

Print debug messages.

Example:
$ firejail --debug firefox

Debug blacklisting.

Example:
$ firejail --debug-blacklists firefox

Print all recognized capabilities in the current Firejail software build and exit.

Example:
$ firejail --debug-caps

Print all recognized error numbers in the current Firejail software build and exit.

Example:
$ firejail --debug-errnos

Debug messages for --private-lib option.
Print all recognized protocols in the current Firejail software build and exit.

Example:
$ firejail --debug-protocols

Print all recognized system calls in the current Firejail software build and exit.

Example:
$ firejail --debug-syscalls

Debug whitelisting.

Example:
$ firejail --debug-whitelists firefox

Use this address as default gateway in the new network namespace.

Example:
$ firejail --net=eth0 --defaultgw=10.10.20.1 firefox

Blacklist /mnt, /media, /run/mount and /run/media access.

Example:
$ firejail --disable-mnt firefox

Set a DNS server for the sandbox. Up to three DNS servers can be defined. Use this option if you don't trust the DNS setup on your network.

Example:
$ firejail --dns=8.8.8.8 --dns=8.8.4.4 firefox

Note: this feature is not supported on systemd-resolved setups.

Print DNS configuration for a sandbox identified by name or by PID.

Example:
$ firejail --name=mygame --caps.drop=all warzone2100 &
$ firejail --dns.print=mygame

Example:
$ firejail --list
3272:netblue::firejail --private firefox
$ firejail --dns.print=3272

Set environment variable in the new sandbox.

Example:
$ firejail --env=LD_LIBRARY_PATH=/opt/test/lib

Print the filesystem log for the sandbox identified by name or by PID.

Example:
$ firejail --name=mygame --caps.drop=all warzone2100 &
$ firejail --fs.print=mygame

Example:
$ firejail --list
3272:netblue::firejail --private firefox
$ firejail --fs.print=3272

Get a file from sandbox container, see FILE TRANSFER section for more details.

-?, --help
Print options end exit.

Set sandbox hostname.

Example:
$ firejail --hostname=officepc firefox

Use file as /etc/hosts.

Example:
$ firejail --hosts-file=~/myhosts firefox

Ignore command in profile file.

Example:
$ firejail --ignore=shell --ignore=seccomp firefox
$ firejail --ignore="net eth0" firefox

Move interface in a new network namespace. Up to four --interface options can be specified. Note: wlan devices are not supported for this option.

Example:
$ firejail --interface=eth1 --interface=eth0.vlan100

Assign IP addresses to the last network interface defined by a --net option. A default gateway is assigned by default.

Example:
$ firejail --net=eth0 --ip=10.10.20.56 firefox

No IP address and no default gateway are configured for the last interface defined by a --net option. Use this option in case you intend to start an external DHCP client in the sandbox.

Example:
$ firejail --net=eth0 --ip=none

If the corresponding interface doesn't have an IP address configured, this option is enabled by default.

Assign IPv6 addresses to the last network interface defined by a --net option.

Example:
$ firejail --net=eth0 --ip6=2001:0db8:0:f101::1/64 firefox

Note: you don't need this option if you obtain your ip6 address from router via SLAAC (your ip6 address and default route will be configured by kernel automatically).

Assign an IP address in the provided range to the last network interface defined by a --net option. A default gateway is assigned by default.

Example:
$ firejail --net=eth0 --iprange=192.168.1.100,192.168.1.150

Enable a new IPC namespace if the sandbox was started as a regular user. IPC namespace is enabled by default for sandboxes started as root.

Example:
$ firejail --ipc-namespace firefox

Join the sandbox identified by name or by PID. By default a /bin/bash shell is started after joining the sandbox. If a program is specified, the program is run in the sandbox. If --join command is issued as a regular user, all security filters are configured for the new process the same they are configured in the sandbox. If --join command is issued as root, the security filters, cgroups and cpus configurations are not applied to the process joining the sandbox.

Example:
$ firejail --name=mygame --caps.drop=all warzone2100 &
$ firejail --join=mygame

Example:
$ firejail --list
3272:netblue::firejail --private firefox
$ firejail --join=3272

Join the mount namespace of the sandbox identified by name or PID. By default a /bin/bash shell is started after joining the sandbox. If a program is specified, the program is run in the sandbox. This command is available only to root user. Security filters, cgroups and cpus configurations are not applied to the process joining the sandbox.

Join the network namespace of the sandbox identified by name. By default a /bin/bash shell is started after joining the sandbox. If a program is specified, the program is run in the sandbox. This command is available only to root user. Security filters, cgroups and cpus configurations are not applied to the process joining the sandbox. Example:

# start firefox
$ firejail --net=eth0 --name=browser firefox &

# change netfilter configuration
$ sudo firejail --join-network=browser bash -c "cat /etc/firejail/nolocal.net | /sbin/iptables-restore"

# verify netfilter configuration
$ sudo firejail --join-network=browser /sbin/iptables -vL

# verify IP addresses
$ sudo firejail --join-network=browser ip addr
Switching to pid 1932, the first child process inside the sandbox
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0-1931: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default
link/ether 76:58:14:42:78:e4 brd ff:ff:ff:ff:ff:ff
inet 192.168.1.158/24 brd 192.168.1.255 scope global eth0-1931
valid_lft forever preferred_lft forever
inet6 fe80::7458:14ff:fe42:78e4/64 scope link
valid_lft forever preferred_lft forever

Join the sandbox identified by name or start a new one. Same as "firejail --join=name" if sandbox with specified name exists, otherwise same as "firejail --name=name ..."
Note that in contrary to other join options there is respective profile option.

/dev/shm directory is untouched (even with --private-dev)

Example:
$ firejail --keep-dev-shm --private-dev

/var/tmp directory is untouched.

Example:
$ firejail --keep-var-tmp

List files in sandbox container, see FILE TRANSFER section for more details.

List all sandboxes, see MONITORING section for more details.

Example:
$ firejail --list
7015:netblue:browser:firejail firefox
7056:netblue:torrent:firejail --net=eth0 transmission-gtk
7064:netblue::firejail --noroot xterm
$

Assign MAC addresses to the last network interface defined by a --net option. This option is not supported for wireless interfaces.

Example:
$ firejail --net=eth0 --mac=00:11:22:33:44:55 firefox

Spoof id number in /etc/machine-id file - a new random id is generated inside the sandbox.

Example:
$ firejail --machine-id

Install a seccomp filter to block attempts to create memory mappings that are both writable and executable, to change mappings to be executable, or to create executable shared memory. The filter examines the arguments of mmap, mmap2, mprotect, pkey_mprotect and shmat system calls and kills the process if necessary.

Note: shmat is not implemented as a system call on some platforms including i386, and it cannot be handled by seccomp-bpf.

Assign a MTU value to the last network interface defined by a --net option.

Example:
$ firejail --net=eth0 --mtu=1492

Set sandbox name. Several options, such as --join and --shutdown, can use this name to identify a sandbox.

In case the name supplied by the user is already in use by another sandbox, Firejail will assign a new name as "name-PID", where PID is the process ID of the sandbox. This functionality can be disabled at run time in /etc/firejail/firejail.config file, by setting "name-change" flag to "no".

Example:
$ firejail --name=browser firefox &
$ firejail --name=browser --private firefox --no-remote &
$ firejail --list
1198:netblue:browser:firejail --name=browser firefox
1312:netblue:browser-1312:firejail --name=browser --private firefox --no-remote

Enable a new network namespace and connect it to this bridge interface. Unless specified with option --ip and --defaultgw, an IP address and a default gateway will be assigned automatically to the sandbox. The IP address is verified using ARP before assignment. The address configured as default gateway is the bridge device IP address. Up to four --net options can be specified.

Example:
$ sudo brctl addbr br0
$ sudo ifconfig br0 10.10.20.1/24
$ sudo brctl addbr br1
$ sudo ifconfig br1 10.10.30.1/24
$ firejail --net=br0 --net=br1

Enable a new network namespace and connect it to this ethernet interface using the standard Linux macvlan|ipvaln driver. Unless specified with option --ip and --defaultgw, an IP address and a default gateway will be assigned automatically to the sandbox. The IP address is verified using ARP before assignment. The address configured as default gateway is the default gateway of the host. Up to four --net options can be specified. Support for ipvlan driver was introduced in Linux kernel 3.19.

Example:
$ firejail --net=eth0 --ip=192.168.1.80 --dns=8.8.8.8 firefox
$ firejail --net=wlan0 firefox

Enable a new network namespace and connect it to this ethernet tap interface using the standard Linux macvlan driver. If the tap interface is not configured, the sandbox will not try to configure the interface inside the sandbox. Please use --ip, --netmask and --defaultgw to specify the configuration.

Example:
$ firejail --net=tap0 --ip=10.10.20.80 --netmask=255.255.255.0 --defaultgw=10.10.20.1 firefox

Enable a new, unconnected network namespace. The only interface available in the new namespace is a new loopback interface (lo). Use this option to deny network access to programs that don't really need network access.

Example:
$ firejail --net=none vlc

Note: --net=none can crash the application on some platforms. In these cases, it can be replaced with --protocol=unix.

If a new network namespace is enabled, print network interface configuration for the sandbox specified by name or PID. Example:

$ firejail --net.print=browser
Switching to pid 1853, the first child process inside the sandbox
Interface MAC IP Mask Status
lo 127.0.0.1 255.0.0.0 UP
eth0-1852 5e:fb:8e:27:29:26 192.168.1.186 255.255.255.0 UP

Enable a default firewall if a new network namespace is created inside the sandbox. This option has no effect for sandboxes using the system network namespace.

The default firewall is optimized for regular desktop applications. No incoming connections are accepted:

*filter
:INPUT DROP [0:0]
:FORWARD DROP [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -i lo -j ACCEPT
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
# allow ping
-A INPUT -p icmp --icmp-type destination-unreachable -j ACCEPT
-A INPUT -p icmp --icmp-type time-exceeded -j ACCEPT
-A INPUT -p icmp --icmp-type echo-request -j ACCEPT
# drop STUN (WebRTC) requests
-A OUTPUT -p udp --dport 3478 -j DROP
-A OUTPUT -p udp --dport 3479 -j DROP
-A OUTPUT -p tcp --dport 3478 -j DROP
-A OUTPUT -p tcp --dport 3479 -j DROP
COMMIT

Example:
$ firejail --net=eth0 --netfilter firefox

Enable the firewall specified by filename if a new network namespace is created inside the sandbox. This option has no effect for sandboxes using the system network namespace.

Please use the regular iptables-save/iptables-restore format for the filter file. The following examples are available in /etc/firejail directory:

webserver.net is a webserver firewall that allows access only to TCP ports 80 and 443. Example:

$ firejail --netfilter=/etc/firejail/webserver.net --net=eth0 \
/etc/init.d/apache2 start

nolocal.net is a desktop client firewall that disable access to local network. Example:

$ firejail --netfilter=/etc/firejail/nolocal.net \
--net=eth0 firefox

This is the template version of the previous command. $ARG1, $ARG2, $ARG3 ... in the firewall script are replaced with arg1, arg2, arg3 ... passed on the command line. Up to 16 arguments are supported. Example:

$ firejail --net=eth0 --ip=192.168.1.105 \
--netfilter=/etc/firejail/tcpserver.net,5001 server-program

Print the firewall installed in the sandbox specified by name or PID. Example:

$ firejail --name=browser --net=eth0 --netfilter firefox &
$ firejail --netfilter.print=browser

Enable the IPv6 firewall specified by filename if a new network namespace is created inside the sandbox. This option has no effect for sandboxes using the system network namespace. Please use the regular iptables-save/iptables-restore format for the filter file.

Print the IPv6 firewall installed in the sandbox specified by name or PID. Example:

$ firejail --name=browser --net=eth0 --netfilter firefox &
$ firejail --netfilter6.print=browser

Use this option when you want to assign an IP address in a new namespace and the parent interface specified by --net is not configured. An IP address and a default gateway address also have to be added. By default the new namespace interface comes without IP address and default gateway configured. Example:

$ sudo /sbin/brctl addbr br0
$ sudo /sbin/ifconfig br0 up
$ firejail --ip=10.10.20.67 --netmask=255.255.255.0 --defaultgw=10.10.20.1

Run the program in a named, persistent network namespace. These can be created and configured using "ip netns".

Monitor network namespace statistics, see MONITORING section for more details.

Example:

$ firejail --netstats
PID User RX(KB/s) TX(KB/s) Command
1294 netblue 53.355 1.473 firejail --net=eth0 firefox
7383 netblue 9.045 0.112 firejail --net=eth0 transmission

Set nice value for all processes running inside the sandbox. Only root may specify a negative value.

Example:
$ firejail --nice=2 firefox

Disable 3D hardware acceleration.

Example:
$ firejail --no3d firefox

Disable blacklist for this directory or file.

Example:
$ firejail
$ nc dict.org 2628
bash: /bin/nc: Permission denied
$ exit

$ firejail --noblacklist=/bin/nc
$ nc dict.org 2628
220 pan.alephnull.com dictd 1.12.1/rf on Linux 3.14-1-amd64

Disable D-Bus access. Only the regular UNIX socket is handled by this command. To disable the abstract socket you would need to request a new network namespace using --net command. Another option is to remove unix from --protocol set.

Example:
$ firejail --nodbus --net=none

Disable DVD and audio CD devices.

Example:
$ firejail --nodvd

Remount directory or file noexec, nodev and nosuid. File globbing is supported, see FILE GLOBBING section for more details.

Example:
$ firejail --noexec=/tmp

/etc and /var are noexec by default if the sandbox was started as a regular user. If there are more than one mount operation on the path of the file or directory, noexec should be applied to the last one. Always check if the change took effect inside the sandbox.

Disable supplementary groups. Without this option, supplementary groups are enabled for the user starting the sandbox. For root user supplementary groups are always disabled.

Note: By default all regular user groups are removed with the exception of the current user. This can be changed using --allusers command option.

Example:
$ id
uid=1000(netblue) gid=1000(netblue) groups=1000(netblue),24(cdrom),25(floppy),27(sudo),29(audio)
$ firejail --nogroups
Parent pid 8704, child pid 8705
Child process initialized
$ id
uid=1000(netblue) gid=1000(netblue) groups=1000(netblue)
$

Do not use a security profile.

Example:
$ firejail
Reading profile /etc/firejail/default.profile
Parent pid 8553, child pid 8554
Child process initialized
[...]

$ firejail --noprofile
Parent pid 8553, child pid 8554
Child process initialized
[...]

Install a user namespace with a single user - the current user. root user does not exist in the new namespace. This option requires a Linux kernel version 3.8 or newer. The option is not supported for --chroot and --overlay configurations, or for sandboxes started as root.

Example:
$ firejail --noroot
Parent pid 8553, child pid 8554
Child process initialized
$ ping google.com
ping: icmp open socket: Operation not permitted
$

Sets the NO_NEW_PRIVS prctl. This ensures that child processes cannot acquire new privileges using execve(2); in particular, this means that calling a suid binary (or one with file capabilities) does not result in an increase of privilege. This option is enabled by default if seccomp filter is activated.

Disable sound system.

Example:
$ firejail --nosound firefox

Disable automatic ~/.config/pulse init, for complex setups such as remote pulse servers or non-standard socket paths.

Example:
$ firejail --noautopulse firefox

Disable DVB (Digital Video Broadcasting) TV devices.

Example:
$ firejail --notv vlc

Disable U2F devices.

Example:
$ firejail --nou2f

Disable video devices.

Disable whitelist for this directory or file.

stdout logging and log rotation. Copy stdout to logfile, and keep the size of the file under 500KB using log rotation. Five files with prefixes .1 to .5 are used in rotation.

Example:
$ firejail --output=sandboxlog /bin/bash
[...]
$ ls -l sandboxlog*
-rw-r--r-- 1 netblue netblue 333890 Jun 2 07:48 sandboxlog
-rw-r--r-- 1 netblue netblue 511488 Jun 2 07:48 sandboxlog.1
-rw-r--r-- 1 netblue netblue 511488 Jun 2 07:48 sandboxlog.2
-rw-r--r-- 1 netblue netblue 511488 Jun 2 07:48 sandboxlog.3
-rw-r--r-- 1 netblue netblue 511488 Jun 2 07:48 sandboxlog.4
-rw-r--r-- 1 netblue netblue 511488 Jun 2 07:48 sandboxlog.5

Similar to --output, but stderr is also stored.

Mount a filesystem overlay on top of the current filesystem. Unlike the regular filesystem container, the system directories are mounted read-write. All filesystem modifications go into the overlay. Directories /run, /tmp and /dev are not covered by the overlay. The overlay is stored in $HOME/.firejail/<PID> directory. If the sandbox is started as a regular user, nonewprivs and a default capabilities filter are enabled.

OverlayFS support is required in Linux kernel for this option to work. OverlayFS was officially introduced in Linux kernel version 3.18. This option is not available on Grsecurity systems.

Example:
$ firejail --overlay firefox

Mount a filesystem overlay on top of the current filesystem. Unlike the regular filesystem container, the system directories are mounted read-write. All filesystem modifications go into the overlay. Directories /run, /tmp and /dev are not covered by the overlay. The overlay is stored in $HOME/.firejail/<NAME> directory. The created overlay can be reused between multiple sessions. If the sandbox is started as a regular user, nonewprivs and a default capabilities filter are enabled.

OverlayFS support is required in Linux kernel for this option to work. OverlayFS was officially introduced in Linux kernel version 3.18. This option is not available on Grsecurity systems.

Example:
$ firejail --overlay-named=jail1 firefox

Mount a filesystem overlay on top of the current filesystem. All filesystem modifications are discarded when the sandbox is closed. Directories /run, /tmp and /dev are not covered by the overlay. If the sandbox is started as a regular user, nonewprivs and a default capabilities filter are enabled.

OverlayFS support is required in Linux kernel for this option to work. OverlayFS was officially introduced in Linux kernel version 3.18. This option is not available on Grsecurity systems.

Example:
$ firejail --overlay-tmpfs firefox

Clean all overlays stored in $HOME/.firejail directory.

Example:
$ firejail --overlay-clean

Mount new /root and /home/user directories in temporary filesystems. All modifications are discarded when the sandbox is closed.

Example:
$ firejail --private firefox

Use directory as user home.

Example:
$ firejail --private=/home/netblue/firefox-home firefox

Build a new user home in a temporary filesystem, and copy the files and directories in the list in the new home. All modifications are discarded when the sandbox is closed.

Example:
$ firejail --private-home=.mozilla firefox

Mount an empty temporary filesystem on top of the .cache directory in user home. All modifications are discarded when the sandbox is closed.

Example:
$ firejail --private-cache openbox

Build a new /bin in a temporary filesystem, and copy the programs in the list. If no listed file is found, /bin directory will be empty. The same directory is also bind-mounted over /sbin, /usr/bin, /usr/sbin and /usr/local/bin. All modifications are discarded when the sandbox is closed. File globbing is supported, see FILE GLOBBING section for more details.

Example:
$ firejail --private-bin=bash,sed,ls,cat
Parent pid 20841, child pid 20842
Child process initialized
$ ls /bin
bash cat ls sed

This feature is currently under heavy development. Only amd64 platforms are supported at this moment. The idea is to build a new /lib in a temporary filesystem, with only the library files necessary to run the application. It could be as simple as:

$ firejail --private-lib galculator

but it gets complicated really fast:

$ firejail --private-lib=x86_64-linux-gnu/xed,x86_64-linux-gnu/gdk-pixbuf-2.0,libenchant.so.1,librsvg-2.so.2 xed

The feature is integrated with --private-bin:

$ firejail --private-lib --private-bin=bash,ls,ps
$ ls /lib
ld-linux-x86-64.so.2 libgpg-error.so.0 libprocps.so.6 libsystemd.so.0
libc.so.6 liblz4.so.1 libpthread.so.0 libtinfo.so.5
libdl.so.2 liblzma.so.5 librt.so.1 x86_64-linux-gnu
libgcrypt.so.20 libpcre.so.3 libselinux.so.1
$ ps
PID TTY TIME CMD
1 pts/0 00:00:00 firejail
45 pts/0 00:00:00 bash
48 pts/0 00:00:00 ps
$

Create a new /dev directory. Only disc, dri, null, full, zero, tty, pts, ptmx, random, snd, urandom, video, log and shm devices are available.

Example:
$ firejail --private-dev
Parent pid 9887, child pid 9888
Child process initialized
$ ls /dev
cdrom cdrw dri dvd dvdrw full log null ptmx pts random shm snd sr0 tty urandom zero
$

Build a new /etc in a temporary filesystem, and copy the files and directories in the list. If no listed file is found, /etc directory will be empty. All modifications are discarded when the sandbox is closed.

Example:
$ firejail --private-etc=group,hostname,localtime, \
nsswitch.conf,passwd,resolv.conf

Build a new /opt in a temporary filesystem, and copy the files and directories in the list. If no listed file is found, /opt directory will be empty. All modifications are discarded when the sandbox is closed.

Example:
$ firejail --private-opt=firefox /opt/firefox/firefox

Build a new /srv in a temporary filesystem, and copy the files and directories in the list. If no listed file is found, /srv directory will be empty. All modifications are discarded when the sandbox is closed.

Example:
# firejail --private-srv=www /etc/init.d/apache2 start

Mount an empty temporary filesystem on top of /tmp directory whitelisting X11 and PulseAudio sockets.

Example:
$ firejail --private-tmp
$ ls -al /tmp
drwxrwxrwt 4 nobody nogroup 80 Apr 30 11:46 .
drwxr-xr-x 30 nobody nogroup 4096 Apr 26 22:18 ..
drwx------ 2 nobody nogroup 4096 Apr 30 10:52 pulse-PKdhtXMmr18n
drwxrwxrwt 2 nobody nogroup 4096 Apr 30 10:52 .X11-unix

Load a custom security profile from filename. For filename use an absolute path or a path relative to the current path. For more information, see SECURITY PROFILES section below.

Example:
$ firejail --profile=myprofile

Print the name of the profile file for the sandbox identified by name or or PID.

Example:
$ firejail --profile.print=browser
/etc/firejail/firefox.profile

Enable protocol filter. The filter is based on seccomp and checks the first argument to socket system call. Recognized values: unix, inet, inet6, netlink and packet. This option is not supported for i386 architecture.

Example:
$ firejail --protocol=unix,inet,inet6 firefox

Print the protocol filter for the sandbox identified by name or PID.

Example:
$ firejail --name=mybrowser firefox &
$ firejail --protocol.print=mybrowser
unix,inet,inet6,netlink

Example:
$ firejail --list
3272:netblue::firejail --private firefox
$ firejail --protocol.print=3272
unix,inet,inet6,netlink

Put a file in sandbox container, see FILE TRANSFER section for more details.
Turn off Firejail's output.
Set directory or file read-only. File globbing is supported, see FILE GLOBBING section for more details.

Example:
$ firejail --read-only=~/.mozilla firefox

A short note about mixing --whitelist and --read-only options. Whitelisted directories should be made read-only independently. Making a parent directory read-only, will not make the whitelist read-only. Example:

$ firejail --whitelist=~/work --read-only=~ --read-only=~/work

Set directory or file read-write. Only files or directories belonging to the current user are allowed for this operation. File globbing is supported, see FILE GLOBBING section for more details. Example:

$ mkdir ~/test
$ touch ~/test/a
$ firejail --read-only=~/test --read-write=~/test/a

Set the maximum size of the process's virtual memory (address space) in bytes.

Set the maximum limit, in seconds, for the amount of CPU time each sandboxed process can consume. When the limit is reached, the processes are killed.

The CPU limit is a limit on CPU seconds rather than elapsed time. CPU seconds is basically how many seconds the CPU has been in use and does not necessarily directly relate to the elapsed time. Linux kernel keeps track of CPU seconds for each process independently.

Set the maximum file size that can be created by a process.
Set the maximum number of files that can be opened by a process.
Set the maximum number of processes that can be created for the real user ID of the calling process.
Set the maximum number of pending signals for a process.

Remove environment variable in the new sandbox.

Example:
$ firejail --rmenv=DBUS_SESSION_BUS_ADDRESS

ARP-scan all the networks from inside a network namespace. This makes it possible to detect macvlan kernel device drivers running on the current host.

Example:
$ firejail --net=eth0 --scan

Enable seccomp filter and blacklist the syscalls in the default list (@default). The default list is as follows: _sysctl, acct, add_key, adjtimex, afs_syscall, bdflush, bpf, break, chroot, clock_adjtime, clock_settime, create_module, delete_module, fanotify_init, finit_module, ftime, get_kernel_syms, getpmsg, gtty, init_module, io_cancel, io_destroy, io_getevents, io_setup, io_submit, ioperm, iopl, ioprio_set, kcmp, kexec_file_load, kexec_load, keyctl, lock, lookup_dcookie, mbind, migrate_pages, modify_ldt, mount, move_pages, mpx, name_to_handle_at, nfsservctl, ni_syscall, open_by_handle_at, pciconfig_iobase, pciconfig_read, pciconfig_write, perf_event_open, personality, pivot_root, process_vm_readv, process_vm_writev, prof, profil, ptrace, putpmsg, query_module, reboot, remap_file_pages, request_key, rtas, s390_mmio_read, s390_mmio_write, s390_runtime_instr, security, set_mempolicy, setdomainname, sethostname, settimeofday, sgetmask, ssetmask, stime, stty, subpage_prot, swapoff, swapon, switch_endian, sys_debug_setcontext, sysfs, syslog, tuxcall, ulimit, umount, umount2, uselib, userfaultfd, ustat, vhangup, vm86, vm86old, vmsplice and vserver.

To help creating useful seccomp filters more easily, the following system call groups are defined: @clock, @cpu-emulation, @debug, @default, @default-nodebuggers, @default-keep, @module, @obsolete, @privileged, @raw-io, @reboot, @resources and @swap. In addition, a system call can be specified by its number instead of name with prefix $, so for example $165 would be equal to mount on i386.

System architecture is strictly imposed only if flag --seccomp.block-secondary is used. The filter is applied at run time only if the correct architecture was detected. For the case of I386 and AMD64 both 32-bit and 64-bit filters are installed.

Firejail will print seccomp violations to the audit log if the kernel was compiled with audit support (CONFIG_AUDIT flag).

Example:
$ firejail --seccomp

Enable seccomp filter, blacklist the default list (@default) and the syscalls or syscall groups specified by the command.

Example:
$ firejail --seccomp=utime,utimensat,utimes firefox
$ firejail --seccomp=@clock,mkdir,unlinkat transmission-gtk

Instead of dropping the syscall, a specific error number can be returned using syscall:errorno syntax.

Example: $ firejail --seccomp=unlinkat:ENOENT,utimensat,utimes
Parent pid 10662, child pid 10663
Child process initialized
$ touch testfile
$ rm testfile
rm: cannot remove `testfile': Operation not permitted

If the blocked system calls would also block Firejail from operating, they are handled by adding a preloaded library which performs seccomp system calls later.

Example:
$ firejail --noprofile --shell=none --seccomp=execve bash
Parent pid 32751, child pid 32752
Post-exec seccomp protector enabled
list in: execve, check list: @default-keep prelist: (null), postlist: execve
Child process initialized in 46.44 ms
$ ls
Bad system call

Enable seccomp filter and filter system call architectures so that only the native architecture is allowed. For example, on amd64, i386 and x32 system calls are blocked as well as changing the execution domain with personality(2) system call.

Enable seccomp filter, and blacklist the syscalls or the syscall groups specified by the command.

Example:
$ firejail --seccomp.drop=utime,utimensat,utimes,@clock

Instead of dropping the syscall, a specific error number can be returned using syscall:errorno syntax.

Example:
$ firejail --seccomp.drop=unlinkat:ENOENT,utimensat,utimes
Parent pid 10662, child pid 10663
Child process initialized
$ touch testfile
$ rm testfile
rm: cannot remove `testfile': Operation not permitted

Enable seccomp filter, and whitelist the syscalls specified by the command. The system calls needed by Firejail (group @default-keep: prctl, execve) are handled with the preload library.

Example:
$ firejail --shell=none --seccomp.keep=poll,select,[...] transmission-gtk

Print the seccomp filter for the sandbox identified by name or PID.

Example:
$ firejail --name=browser firefox &
$ firejail --seccomp.print=browser
line OP JT JF K
=================================
0000: 20 00 00 00000004 ld data.architecture
0001: 15 01 00 c000003e jeq ARCH_64 0003 (false 0002)
0002: 06 00 00 7fff0000 ret ALLOW
0003: 20 00 00 00000000 ld data.syscall-number
0004: 35 01 00 40000000 jge X32_ABI true:0006 (false 0005)
0005: 35 01 00 00000000 jge read 0007 (false 0006)
0006: 06 00 00 00050001 ret ERRNO(1)
0007: 15 41 00 0000009a jeq modify_ldt 0049 (false 0008)
0008: 15 40 00 000000d4 jeq lookup_dcookie 0049 (false 0009)
0009: 15 3f 00 0000012a jeq perf_event_open 0049 (false 000a)
000a: 15 3e 00 00000137 jeq process_vm_writev 0049 (false 000b)
000b: 15 3d 00 0000009c jeq _sysctl 0049 (false 000c)
000c: 15 3c 00 000000b7 jeq afs_syscall 0049 (false 000d)
000d: 15 3b 00 000000ae jeq create_module 0049 (false 000e)
000e: 15 3a 00 000000b1 jeq get_kernel_syms 0049 (false 000f)
000f: 15 39 00 000000b5 jeq getpmsg 0049 (false 0010)
0010: 15 38 00 000000b6 jeq putpmsg 0049 (false 0011)
0011: 15 37 00 000000b2 jeq query_module 0049 (false 0012)
0012: 15 36 00 000000b9 jeq security 0049 (false 0013)
0013: 15 35 00 0000008b jeq sysfs 0049 (false 0014)
0014: 15 34 00 000000b8 jeq tuxcall 0049 (false 0015)
0015: 15 33 00 00000086 jeq uselib 0049 (false 0016)
0016: 15 32 00 00000088 jeq ustat 0049 (false 0017)
0017: 15 31 00 000000ec jeq vserver 0049 (false 0018)
0018: 15 30 00 0000009f jeq adjtimex 0049 (false 0019)
0019: 15 2f 00 00000131 jeq clock_adjtime 0049 (false 001a)
001a: 15 2e 00 000000e3 jeq clock_settime 0049 (false 001b)
001b: 15 2d 00 000000a4 jeq settimeofday 0049 (false 001c)
001c: 15 2c 00 000000b0 jeq delete_module 0049 (false 001d)
001d: 15 2b 00 00000139 jeq finit_module 0049 (false 001e)
001e: 15 2a 00 000000af jeq init_module 0049 (false 001f)
001f: 15 29 00 000000ad jeq ioperm 0049 (false 0020)
0020: 15 28 00 000000ac jeq iopl 0049 (false 0021)
0021: 15 27 00 000000f6 jeq kexec_load 0049 (false 0022)
0022: 15 26 00 00000140 jeq kexec_file_load 0049 (false 0023)
0023: 15 25 00 000000a9 jeq reboot 0049 (false 0024)
0024: 15 24 00 000000a7 jeq swapon 0049 (false 0025)
0025: 15 23 00 000000a8 jeq swapoff 0049 (false 0026)
0026: 15 22 00 000000a3 jeq acct 0049 (false 0027)
0027: 15 21 00 00000141 jeq bpf 0049 (false 0028)
0028: 15 20 00 000000a1 jeq chroot 0049 (false 0029)
0029: 15 1f 00 000000a5 jeq mount 0049 (false 002a)
002a: 15 1e 00 000000b4 jeq nfsservctl 0049 (false 002b)
002b: 15 1d 00 0000009b jeq pivot_root 0049 (false 002c)
002c: 15 1c 00 000000ab jeq setdomainname 0049 (false 002d)
002d: 15 1b 00 000000aa jeq sethostname 0049 (false 002e)
002e: 15 1a 00 000000a6 jeq umount2 0049 (false 002f)
002f: 15 19 00 00000099 jeq vhangup 0049 (false 0030)
0030: 15 18 00 000000ee jeq set_mempolicy 0049 (false 0031)
0031: 15 17 00 00000100 jeq migrate_pages 0049 (false 0032)
0032: 15 16 00 00000117 jeq move_pages 0049 (false 0033)
0033: 15 15 00 000000ed jeq mbind 0049 (false 0034)
0034: 15 14 00 00000130 jeq open_by_handle_at 0049 (false 0035)
0035: 15 13 00 0000012f jeq name_to_handle_at 0049 (false 0036)
0036: 15 12 00 000000fb jeq ioprio_set 0049 (false 0037)
0037: 15 11 00 00000067 jeq syslog 0049 (false 0038)
0038: 15 10 00 0000012c jeq fanotify_init 0049 (false 0039)
0039: 15 0f 00 00000138 jeq kcmp 0049 (false 003a)
003a: 15 0e 00 000000f8 jeq add_key 0049 (false 003b)
003b: 15 0d 00 000000f9 jeq request_key 0049 (false 003c)
003c: 15 0c 00 000000fa jeq keyctl 0049 (false 003d)
003d: 15 0b 00 000000ce jeq io_setup 0049 (false 003e)
003e: 15 0a 00 000000cf jeq io_destroy 0049 (false 003f)
003f: 15 09 00 000000d0 jeq io_getevents 0049 (false 0040)
0040: 15 08 00 000000d1 jeq io_submit 0049 (false 0041)
0041: 15 07 00 000000d2 jeq io_cancel 0049 (false 0042)
0042: 15 06 00 000000d8 jeq remap_file_pages 0049 (false 0043)
0043: 15 05 00 00000116 jeq vmsplice 0049 (false 0044)
0044: 15 04 00 00000087 jeq personality 0049 (false 0045)
0045: 15 03 00 00000143 jeq userfaultfd 0049 (false 0046)
0046: 15 02 00 00000065 jeq ptrace 0049 (false 0047)
0047: 15 01 00 00000136 jeq process_vm_readv 0049 (false 0048)
0048: 06 00 00 7fff0000 ret ALLOW
0049: 06 00 01 00000000 ret KILL
$

Run the program directly, without a user shell.

Example:
$ firejail --shell=none script.sh

Set default user shell. Use this shell to run the application using -c shell option. For example "firejail --shell=/bin/dash firefox" will start Mozilla Firefox as "/bin/dash -c firefox". By default Bash shell (/bin/bash) is used.

Example: $firejail --shell=/bin/dash script.sh

Shutdown the sandbox identified by name or PID.

Example:
$ firejail --name=mygame --caps.drop=all warzone2100 &
$ firejail --shutdown=mygame

Example:
$ firejail --list
3272:netblue::firejail --private firefox
$ firejail --shutdown=3272

Kill the sandbox automatically after the time has elapsed. The time is specified in hours/minutes/seconds format.

$ firejail --timeout=01:30:00 firefox

Mount a writable tmpfs filesystem on directory dirname. This option is available only when running the sandbox as root. File globbing is supported, see FILE GLOBBING section for more details.

Example:
# firejail --tmpfs=/var

Monitor the most CPU-intensive sandboxes, see MONITORING section for more details.

Example:
$ firejail --top

Trace open, access and connect system calls.

Example:
$ firejail --trace wget -q www.debian.org
Reading profile /etc/firejail/wget.profile
3:wget:fopen64 /etc/wgetrc:0x5c8e8ce6c0
3:wget:fopen /etc/hosts:0x5c8e8cfb70
3:wget:socket AF_INET SOCK_DGRAM IPPROTO_IP:3
3:wget:connect 3 8.8.8.8 port 53:0
3:wget:socket AF_INET SOCK_STREAM IPPROTO_IP:3
3:wget:connect 3 130.89.148.14 port 80:0
3:wget:fopen64 index.html:0x5c8e8d1a60

parent is shutting down, bye...

This option enables auditing blacklisted files and directories. A message is sent to syslog in case the file or the directory is accessed.

Example:
$ firejail --tracelog firefox

Sample messages:
$ sudo tail -f /var/log/syslog
[...]
Dec 3 11:43:25 debian firejail[70]: blacklist violation - sandbox 26370, exe firefox, syscall open64, path /etc/shadow
Dec 3 11:46:17 debian firejail[70]: blacklist violation - sandbox 26370, exe firefox, syscall opendir, path /boot
[...]

Print a tree of all sandboxed processes, see MONITORING section for more details.

Example:
$ firejail --tree
11903:netblue:firejail iceweasel
11904:netblue:iceweasel
11957:netblue:/usr/lib/iceweasel/plugin-container
11969:netblue:firejail --net=eth0 transmission-gtk
11970:netblue:transmission-gtk

Connect the sandbox to a network overlay/VPN tunnel created by firetunnel utility. This options tries first the client side of the tunnel. If this fails, it tries the server side. If multiple tunnels are active, please specify the tunnel device using --tunnel=devname.

The available tunnel devices are listed in /etc/firetunnel directory, one file for each device. The files are regular firejail profile files containing the network configuration, and are created and managed by firetunnel utility. By default ftc is the client-side device and fts is the server-side device. For more information please see man 1 firetunnel.

Example:
$ firejail --tunnel firefox

Print program version and exit.

Example:
$ firejail --version
firejail version 0.9.27

Use this name for the interface connected to the bridge for --net=bridge_interface commands, instead of the default one.

Example:
$ firejail --net=br0 --veth-name=if0

Whitelist directory or file. A temporary file system is mounted on the top directory, and the whitelisted files are mount-binded inside. Modifications to whitelisted files are persistent, everything else is discarded when the sandbox is closed. The top directory could be user home, /dev, /etc, /media, /mnt, /opt, /srv, /sys/module, /usr/share, /var, and /tmp.

Symbolic link handling: with the exception of user home, both the link and the real file should be in the same top directory. For user home, both the link and the real file should be owned by the user.

Example:
$ firejail --noprofile --whitelist=~/.mozilla
$ firejail --whitelist=/tmp/.X11-unix --whitelist=/dev/null
$ firejail "--whitelist=/home/username/My Virtual Machines"

Mount /etc directory read-write.

Example:
$ sudo firejail --writable-etc

Disable the default blacklisting of /run/user/$UID/systemd and /run/user/$UID/gnupg.

Example:
$ sudo firejail --writable-run-user

Mount /var directory read-write.

Example:
$ sudo firejail --writable-var

Use the real /var/log directory, not a clone. By default, a tmpfs is mounted on top of /var/log directory, and a skeleton filesystem is created based on the original /var/log.

Example:
$ sudo firejail --writable-var-log

Sandbox the application using Xpra, Xephyr, Xvfb or Xorg security extension. The sandbox will prevents screenshot and keylogger applications started inside the sandbox from accessing clients running outside the sandbox. Firejail will try first Xpra, and if Xpra is not installed on the system, it will try to find Xephyr. If all fails, Firejail will not attempt to use Xvfb or X11 security extension.

Xpra, Xephyr and Xvfb modes require a network namespace to be instantiated in order to disable X11 abstract Unix socket. If this is not possible, the user can disable the abstract socket by adding "-nolisten local" on Xorg command line at system level.

Example:
$ firejail --x11 --net=eth0 firefox

Blacklist /tmp/.X11-unix directory, ${HOME}/.Xauthority and the file specified in ${XAUTHORITY} environment variable. Remove DISPLAY and XAUTHORITY environment variables. Stop with error message if X11 abstract socket will be accessible in jail.

Start Xephyr and attach the sandbox to this server. Xephyr is a display server implementing the X11 display server protocol. A network namespace needs to be instantiated in order to deny access to X11 abstract Unix domain socket.

Xephyr runs in a window just like any other X11 application. The default window size is 800x600. This can be modified in /etc/firejail/firejail.config file.

The recommended way to use this feature is to run a window manager inside the sandbox. A security profile for OpenBox is provided.

Xephyr is developed by Xorg project. On Debian platforms it is installed with the command sudo apt-get install xserver-xephyr. This feature is not available when running as root.

Example:
$ firejail --x11=xephyr --net=eth0 openbox

Sandbox the application using the untrusted mode implemented by X11 security extension. The extension is available in Xorg package and it is installed by default on most Linux distributions. It provides support for a simple trusted/untrusted connection model. Untrusted clients are restricted in certain ways to prevent them from reading window contents of other clients, stealing input events, etc.

The untrusted mode has several limitations. A lot of regular programs assume they are a trusted X11 clients and will crash or lock up when run in untrusted mode. Chromium browser and xterm are two examples. Firefox and transmission-gtk seem to be working fine. A network namespace is not required for this option.

Example:
$ firejail --x11=xorg firefox

Start Xpra (https://xpra.org) and attach the sandbox to this server. Xpra is a persistent remote display server and client for forwarding X11 applications and desktop screens. A network namespace needs to be instantiated in order to deny access to X11 abstract Unix domain socket.

On Debian platforms Xpra is installed with the command sudo apt-get install xpra. This feature is not available when running as root.

Example:
$ firejail --x11=xpra --net=eth0 firefox

Start Xvfb X11 server and attach the sandbox to this server. Xvfb, short for X virtual framebuffer, performs all graphical operations in memory without showing any screen output. Xvfb is mainly used for remote access and software testing on headless servers.

On Debian platforms Xvfb is installed with the command sudo apt-get install xvfb. This feature is not available when running as root.

Example: remote VNC access

On the server we start a sandbox using Xvfb and openbox window manager. The default size of Xvfb screen is 800x600 - it can be changed in /etc/firejail/firejail.config (xvfb-screen). Some sort of networking (--net) is required in order to isolate the abstract sockets used by other X servers.

$ firejail --net=none --x11=xvfb openbox

*** Attaching to Xvfb display 792 ***

Reading profile /etc/firejail/openbox.profile
Reading profile /etc/firejail/disable-common.inc
Reading profile /etc/firejail/disable-common.local
Parent pid 5400, child pid 5401

On the server we also start a VNC server and attach it to the display handled by our Xvfb server (792).

$ x11vnc -display :792

On the client machine we start a VNC viewer and use it to connect to our server:

$ vncviewer

Set screen size for --x11=xephyr. The setting will overwrite the default set in /etc/firejail/firejail.config for the current sandbox. Run xrandr to get a list of supported resolutions on your computer.

Example:
$ firejail --net=eth0 --x11=xephyr --xephyr-screen=640x480 firefox

A symbolic link to /usr/bin/firejail under the name of a program, will start the program in Firejail sandbox. The symbolic link should be placed in the first $PATH position. On most systems, a good place is /usr/local/bin directory. Example:

Make a firefox symlink to /usr/bin/firejail:

$ ln -s /usr/bin/firejail /usr/local/bin/firefox

Verify $PATH

$ which -a firefox
/usr/local/bin/firefox
/usr/bin/firefox

Starting firefox in this moment, automatically invokes “firejail firefox”.

This works for clicking on desktop environment icons, menus etc. Use "firejail --tree" to verify the program is sandboxed.

$ firejail --tree
1189:netblue:firejail firefox
1190:netblue:firejail firefox
1220:netblue:/bin/sh -c "/usr/lib/firefox/firefox"
1221:netblue:/usr/lib/firefox/firefox

We provide a tool that automates all this integration, please see man 1 firecfg for more details.

- '?' matches any character
- '*' matches any string
- '[' denotes a range of characters

$ firejail --private-bin=sh,bash,python*
$ firejail --blacklist=~/dir[1234]
$ firejail --read-only=~/dir[1-4]

$ ./configure --prefix=/usr --enable-apparmor

# apparmor_parser -r /etc/apparmor.d/firejail-default

- Disable ptrace. With ptrace it is possible to inspect and hijack running programs. Usually this is needed only for debugging. You should have no problems running Chromium or Firefox. This feature is available only on Ubuntu kernels.

- Whitelist write access to several files under /run, /proc and /sys.

- Allow running programs only from well-known system paths, such as /bin, /sbin, /usr/bin etc. Those paths are available as read-only. Running programs and scripts from user home or other directories writable by the user is not allowed.

- Prevent using non-standard network sockets. Only unix, inet, inet6, netlink, raw and packet are allowed.

- Deny access to known sensitive paths like .snapshots.

$ firejail --apparmor firefox

These features allow the user to inspect the filesystem container of an existing sandbox and transfer files from the container to the host filesystem.

Retrieve the container file and store it on the host in the current working directory. The container is specified by name or PID.

List container files. The container is specified by name or PID.

Put src-filename in sandbox container. The container is specified by name or PID.

$ firejail --name=mybrowser --private firefox

$ firejail --ls=mybrowser ~/Downloads
drwxr-xr-x netblue netblue 4096 .
drwxr-xr-x netblue netblue 4096 ..
-rw-r--r-- netblue netblue 7847 x11-x305.png
-rw-r--r-- netblue netblue 6800 x11-x642.png
-rw-r--r-- netblue netblue 34139 xpra-clipboard.png

$ firejail --get=mybrowser ~/Downloads/xpra-clipboard.png

$ firejail --put=mybrowser xpra-clipboard.png ~/Downloads/xpra-clipboard.png

Network bandwidth is an expensive resource shared among all sandboxes running on a system. Traffic shaping allows the user to increase network performance by controlling the amount of data that flows into and out of the sandboxes.

Firejail implements a simple rate-limiting shaper based on Linux command tc. The shaper works at sandbox level, and can be used only for sandboxes configured with new network namespaces.

Set rate-limits:

$ firejail --bandwidth=name|pid set network download upload

Clear rate-limits:

$ firejail --bandwidth=name|pid clear network

Status:

$ firejail --bandwidth=name|pid status

where:
name - sandbox name
pid - sandbox pid
network - network interface as used by --net option
download - download speed in KB/s (kilobyte per second)
upload - upload speed in KB/s (kilobyte per second)

Example:
$ firejail --name=mybrowser --net=eth0 firefox &
$ firejail --bandwidth=mybrowser set eth0 80 20
$ firejail --bandwidth=mybrowser status
$ firejail --bandwidth=mybrowser clear eth0

Audit feature allows the user to point out gaps in security profiles. The implementation replaces the program to be sandboxed with a test program. By default, we use faudit program distributed with Firejail. A custom test program can also be supplied by the user. Examples:

Running the default audit program:
$ firejail --audit transmission-gtk

Running a custom audit program:
$ firejail --audit=~/sandbox-test transmission-gtk

In the examples above, the sandbox configures transmission-gtk profile and starts the test program. The real program, transmission-gtk, will not be started.

Limitations: audit feature is not implemented for --x11 commands.

Option --list prints a list of all sandboxes. The format for each process entry is as follows:

PID:USER:Sandbox Name:Command

Option --tree prints the tree of processes running in the sandbox. The format for each process entry is as follows:

PID:USER:Sandbox Name:Command

Option --top is similar to the UNIX top command, however it applies only to sandboxes.

Option --netstats prints network statistics for active sandboxes installing new network namespaces.

Listed below are the available fields (columns) in alphabetical order for --top and --netstats options:

Command used to start the sandbox.
CPU usage, the sandbox share of the elapsed CPU time since the last screen update
Unique process ID for the task controlling the sandbox.
Number of processes running in sandbox, including the controlling process.
Resident Memory Size (KiB), sandbox non-swapped physical memory. It is a sum of the RES values for all processes running in the sandbox.
Network receive speed.
The name of the sandbox, if any.
Shared Memory Size (KiB), it reflects memory shared with other processes. It is a sum of the SHR values for all processes running in the sandbox, including the controlling process.
Network transmit speed.
Sandbox running time in hours:minutes:seconds format.
The owner of the sandbox.

Several command line options can be passed to the program using profile files. Firejail chooses the profile file as follows:

1. If a profile file is provided by the user with --profile=FILE option, the profile FILE is loaded. If a profile name is given, it is searched for first in the ~/.config/firejail directory and if not found then in /etc/firejail directory. Profile names do not include the .profile suffix. If there is a file with the same name as the given profile name, it will be used instead of doing the profile search. To force a profile search, prefix the profile name with a colon (:), eg. --profile=:PROFILE_NAME. Example:

$ firejail --profile=/home/netblue/icecat.profile icecat
Reading profile /home/netblue/icecat.profile
[...]

$ firejail --profile=icecat icecat-wrapper.sh
Reading profile /etc/firejail/icecat.profile
[...]

2. If a profile file with the same name as the application is present in ~/.config/firejail directory or in /etc/firejail, the profile is loaded. ~/.config/firejail takes precedence over /etc/firejail. Example:

$ firejail icecat
Command name #icecat#
Found icecat profile in /home/netblue/.config/firejail directory
Reading profile /home/netblue/.config/firejail/icecat.profile
[...]

3. Use default.profile file if the sandbox is started by a regular user, or server.profile file if the sandbox is started by root. Firejail looks for these files in ~/.config/firejail directory, followed by /etc/firejail directory. To disable default profile loading, use --noprofile command option. Example:

$ firejail
Reading profile /etc/firejail/default.profile
Parent pid 8553, child pid 8554
Child process initialized
[...]

$ firejail --noprofile
Parent pid 8553, child pid 8554
Child process initialized
[...]

See man 5 firejail-profile for profile file syntax information.

To configure a restricted shell, replace /bin/bash with /usr/bin/firejail in /etc/passwd file for each user that needs to be restricted. Alternatively, you can specify /usr/bin/firejail in adduser command:

adduser --shell /usr/bin/firejail username

Additional arguments passed to firejail executable upon login are declared in /etc/firejail/login.users file.

firejail
Sandbox a regular /bin/bash session.
firejail firefox
Start Mozilla Firefox.
firejail --debug firefox
Debug Firefox sandbox.
firejail --private firefox
Start Firefox with a new, empty home directory.
firejail --net=none vlc
Start VLC in an unconnected network namespace.
firejail --net=eth0 firefox
Start Firefox in a new network namespace. An IP address is assigned automatically.
firejail --net=br0 --ip=10.10.20.5 --net=br1 --net=br2
Start a /bin/bash session in a new network namespace and connect it to br0, br1, and br2 host bridge devices. IP addresses are assigned automatically for the interfaces connected to br1 and b2
firejail --list
List all sandboxed processes.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

Homepage: https://firejail.wordpress.com

firemon(1), firecfg(1), firejail-profile(5), firejail-login(5) firejail-users(5)

Jun 2022 0.9.58.2