NAME¶

Firejail - Linux namespaces sandbox program

SYNOPSIS¶

Start a sandbox: File transfer from an existing sandbox Network traffic shaping for an existing sandbox: Monitoring: Miscellaneous:

DESCRIPTION¶

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.

USAGE¶

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

OPTIONS¶

--

Signal the end of options and disables further option processing.

--allow-debuggers

Allow tools such as strace and gdb inside the sandbox. 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

--allusers

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

 

 

Example:

 

$ firejail --allusers

--apparmor

Enable AppArmor confinement. For more information, please see APPARMOR section below.

--appimage

Sandbox an AppImage (http://appimage.org/) application.

 

 

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

--audit

Audit the sandbox, see AUDIT section for more details.

--audit=test-program

Audit the sandbox, see AUDIT section for more details.

--bandwidth=name|pid

Set bandwidth limits for the sandbox identified by name or PID, see TRAFFIC SHAPING section for more details.

--bind=filename1,filename2

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=dirname_or_filename

Blacklist directory or file.

 

 

Example:

 

$ firejail --blacklist=/sbin --blacklist=/usr/sbin

 

$ firejail --blacklist=~/.mozilla

 

$ firejail "--blacklist=/home/username/My Virtual Machines"

 

$ firejail --blacklist=/home/username/My\ Virtual\ Machines

-c

Execute command and exit.

--caps

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

--caps.drop=all

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

--caps.drop=capability,capability,capability

Define a custom blacklist Linux capabilities filter.

 

 

Example:

 

$ firejail --caps.keep=net_broadcast,net_admin,net_raw

--caps.keep=capability,capability,capability

Define a custom whitelist Linux capabilities filter.

 

 

Example:

 

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

--caps.print=name|pid

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

--cgroup=tasks-file

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=dirname

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, default seccomp and capabilities filters are enabled. This option is not available on Grsecurity systems.

 

 

Example:

 

$ firejail --chroot=/media/ubuntu warzone2100

--cpu=cpu-number,cpu-number,cpu-number

Set CPU affinity.

 

 

Example:

 

$ firejail --cpu=0,1 handbrake

--cpu.print=name|pid

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

--csh

Use /bin/csh as default user shell.

 

 

Example:

 

$ firejail --csh

--debug

Print debug messages.

 

 

Example:

 

$ firejail --debug firefox

--debug-blacklists

Debug blacklisting.

 

 

Example:

 

$ firejail --debug-blacklists firefox

--debug-caps

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

 

 

Example:

 

$ firejail --debug-caps

--debug-check-filename

Debug filename checking.

 

 

Example:

 

$ firejail --debug-check-filename firefox

--debug-errnos

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

 

 

Example:

 

$ firejail --debug-errnos

--debug-protocols

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

 

 

Example:

 

$ firejail --debug-protocols

--debug-syscalls

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

 

 

Example:

 

$ firejail --debug-syscalls

--debug-whitelists

Debug whitelisting.

 

 

Example:

 

$ firejail --debug-whitelists firefox

--defaultgw=address

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

 

 

Example:

 

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

--dns=address

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

--dns.print=name|pid

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

--env=name=value

Set environment variable in the new sandbox.

 

 

Example:

 

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

--force

By default, if Firejail is started in an existing sandbox, it will run the program in a bash shell. This option disables this behavior, and attempts to start Firejail in the existing sandbox. There could be lots of reasons for it to fail, for example if the existing sandbox disables admin capabilities, SUID binaries, or if it runs seccomp.

--fs.print=name|print

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=name|pid filename

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

-?, --help

Print options end exit.

--hostname=name

Set sandbox hostname.

 

 

Example:

 

$ firejail --hostname=officepc firefox

--ignore=command

Ignore command in profile file.

 

 

Example:

 

$ firejail --ignore=shell --ignore=seccomp firefox

--interface=interface

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

--ip=address

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

--ip=none

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.

--ip6=address

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).

--iprange=address,address

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

--ipc-namespace

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=name|pid

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-filesystem=name|pid

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-network=name|PID

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-or-start=name

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.

--ls=name|pid dir_or_filename

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

--list

List all sandboxes, see MONITORING section for more details.

 

 

Example:

 

$ firejail --list

 

7015:netblue:firejail firefox

 

7056:netblue:firejail --net=eth0 transmission-gtk

 

7064:netblue:firejail --noroot xterm

 

$

--mac=address

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

 

 

Example:

 

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

--machine-id

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

 

 

Example:

 

$ firejail --machine-id

--mtu=number

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

 

 

Example:

 

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

--name=name

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

 

 

Example:

 

$ firejail --name=mybrowser firefox

--net=bridge_interface

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 bridge devices can be defined. Mixing bridge and macvlan devices is allowed.

 

 

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

--net=ethernet_interface

Enable a new network namespace and connect it to this ethernet interface using the standard Linux macvlan 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 devices can be defined. Mixing bridge and macvlan devices is allowed. Note: wlan devices are not supported for this option.

 

 

Example:

 

$ firejail --net=eth0 --ip=192.168.1.80 --dns=8.8.8.8 firefox

--net=none

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

--netfilter

Enable a default client network filter in the new network namespace. New network namespaces are created using --net option. If a new network namespaces is not created, --netfilter option does nothing. The default filter is as follows:

 

 

*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

--netfilter=filename

Enable the network filter specified by filename in the new network namespace. The filter file format is the format of iptables-save and iptable-restore commands. New network namespaces are created using --net option. If a new network namespaces is not created, --netfilter option does nothing.

 

 

The following filters are available in /etc/firejail directory:

 

 

webserver.net is a webserver filter 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 client filter that disable access to local network. Example:

 

 

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

 

--net=eth0 firefox

--netfilter6=filename

Enable the IPv6 network filter specified by filename in the new network namespace. The filter file format is the format of ip6tables-save and ip6table-restore commands. New network namespaces are created using --net option. If a new network namespaces is not created, --netfilter6 option does nothing.

--netstats

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

--nice=value

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

 

 

Example:

 

$ firejail --nice=2 firefox

--no3d

Disable 3D hardware acceleration.

 

 

Example:

 

$ firejail --no3d firefox

--noblacklist=dirname_or_filename

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

 

--noexec=dirname_or_filename

Remount directory or file noexec, nodev and nosuid.

 

 

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.

--nogroups

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

 

 

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)

 

$

--noprofile

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

 

[...]

--noroot

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

 

$

--nonewprivs

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.

--nosound

Disable sound system.

 

 

Example:

 

$ firejail --nosound firefox

--output=logfile

stdout logging and log rotation. Copy stdout and stderr 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

--overlay

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. The overlay is stored in $HOME/.firejail/<PID> directory.

 

 

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

--overlay-named=name

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. The overlay is stored in $HOME/.firejail/<NAME> directory. The created overlay can be reused between multiple sessions.

 

 

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

--overlay-tmpfs

Mount a filesystem overlay on top of the current filesystem. All filesystem modifications go into the overlay, and are discarded when the sandbox is closed.

 

 

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

--overlay-clean

Clean all overlays stored in $HOME/.firejail directory. Overlays created with --overlay-path=path outside $HOME/.firejail will not be deleted.

 

 

Example:

 

$ firejail --overlay-clean

--private

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

 

 

Example:

 

$ firejail --private firefox

--private=directory

Use directory as user home.

 

 

Example:

 

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

--private-home=file,directory

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

--private-bin=file,file

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.

 

 

Example:

 

$ firejail --private-bin=bash,sed,ls,cat

 

Parent pid 20841, child pid 20842

 

Child process initialized

 

$ ls /bin

 

bash cat ls sed

--private-dev

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

 

 

Example:

 

$ firejail --private-dev

 

Parent pid 9887, child pid 9888

 

Child process initialized

 

$ ls /dev

 

dri full log null ptmx pts random shm snd tty urandom zero

 

$

--private-etc=file,directory

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

--private-tmp

Mount an empty temporary filesystem on top of /tmp directory.

 

 

Example:

 

$ firejail --private-tmp

--profile=filename

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

--profile-path=directory

Use this directory to look for profile files. Use an absolute path or a path in the home directory starting with ~/. For more information, see SECURITY PROFILES section below and RELOCATING PROFILE FILES in man 5 firejail-profile.

 

 

Example:

 

$ firejail --profile-path=~/myprofiles

 

$ firejail --profile-path=/home/netblue/myprofiles

--protocol=protocol,protocol,protocol

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

--protocol.print=name|pid

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=name|pid src-filename dest-filename

Put a file in sandbox container, see FILE TRANSFER section for more details.

--quiet

Turn off Firejail's output.

--read-only=dirname_or_filename

Set directory or file read-only.

 

 

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

--read-write=dirname_or_filename

Set directory or file read-write. Only files or directories belonging to the current user are allowed for this operation. Example:

 

 

$ mkdir ~/test

 

$ touch ~/test/a

 

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

--rlimit-fsize=number

Set the maximum file size that can be created by a process.

--rlimit-nofile=number

Set the maximum number of files that can be opened by a process.

--rlimit-nproc=number

Set the maximum number of processes that can be created for the real user ID of the calling process.

--rlimit-sigpending=number

Set the maximum number of pending signals for a process.

--rmenv=name

Remove environment variable in the new sandbox.

 

 

Example:

 

$ firejail --rmenv=DBUS_SESSION_BUS_ADDRESS

--scan

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

--seccomp

Enable seccomp filter and blacklist the syscalls in the default list. The default list is as follows: mount, umount2, ptrace, kexec_load, kexec_file_load, name_to_handle_at, open_by_handle_at, create_module, init_module, finit_module, delete_module, iopl, ioperm, ioprio_set, swapon, swapoff, syslog, process_vm_readv, process_vm_writev, sysfs,_sysctl, adjtimex, clock_adjtime, lookup_dcookie, perf_event_open, fanotify_init, kcmp, add_key, request_key, keyctl, uselib, acct, modify_ldt, pivot_root, io_setup, io_destroy, io_getevents, io_submit, io_cancel, remap_file_pages, mbind, get_mempolicy, set_mempolicy, migrate_pages, move_pages, vmsplice, chroot, tuxcall, reboot, mfsservctl and get_kernel_syms.

 

 

System architecture is not strictly imposed. 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.

 

 

Example:

 

$ firejail --seccomp

--seccomp=syscall,syscall,syscall

Enable seccomp filter, blacklist the default list and the syscalls specified by the command.

 

 

Example:

 

$ firejail --seccomp=utime,utimensat,utimes firefox

--seccomp.drop=syscall,syscall,syscall

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

 

 

Example:

 

$ firejail --seccomp.drop=utime,utimensat,utimes

--seccomp.keep=syscall,syscall,syscall

Enable seccomp filter, and whitelist the syscalls specified by the command.

 

 

Example:

 

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

--seccomp.<errno>=syscall,syscall,syscall

Enable seccomp filter, and return errno for the syscalls specified by the command.

 

 

Example: a Bash shell where deleting files is disabled

 

 

$ firejail --seccomp.eperm=unlinkat

 

Parent pid 10662, child pid 10663

 

Child process initialized

 

$ touch testfile

 

$ rm testfile

 

rm: cannot remove `testfile': Operation not permitted

--seccomp.print=name|PID

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

 

 

Example:

 

$ firejail --name=browser firefox &

 

$ firejail --seccomp.print=browser

 

SECCOMP Filter:

 

VALIDATE_ARCHITECTURE

 

EXAMINE_SYSCALL

 

BLACKLIST 165 mount

 

BLACKLIST 166 umount2

 

BLACKLIST 101 ptrace

 

BLACKLIST 246 kexec_load

 

BLACKLIST 304 open_by_handle_at

 

BLACKLIST 175 init_module

 

BLACKLIST 176 delete_module

 

BLACKLIST 172 iopl

 

BLACKLIST 173 ioperm

 

BLACKLIST 167 swapon

 

BLACKLIST 168 swapoff

 

BLACKLIST 103 syslog

 

BLACKLIST 310 process_vm_readv

 

BLACKLIST 311 process_vm_writev

 

BLACKLIST 133 mknod

 

BLACKLIST 139 sysfs

 

BLACKLIST 156 _sysctl

 

BLACKLIST 159 adjtimex

 

BLACKLIST 305 clock_adjtime

 

BLACKLIST 212 lookup_dcookie

 

BLACKLIST 298 perf_event_open

 

BLACKLIST 300 fanotify_init

 

RETURN_ALLOW

 

$

--shell=none

Run the program directly, without a user shell.

 

 

Example:

 

$ firejail --shell=none script.sh

--shell=program

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. Options such as --zsh and --csh can also set the default shell.

 

 

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

--shutdown=name|PID

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

--tmpfs=dirname

Mount a tmpfs filesystem on directory dirname. This option is available only when running the sandbox as root.

 

 

Example:

 

# firejail --tmpfs=/var

--top

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

 

 

Example:

 

$ firejail --top

--trace

Trace open, access and connect system calls.

 

 

Example:

 

$ firejail --trace wget -q www.debian.org

 

Parent pid 11793, child pid 11794

 

Child process initialized

 

1:bash:open /dev/tty

 

1:wget:fopen64 /etc/wgetrc

 

1:wget:fopen /etc/hosts

 

1:wget:socket AF_INET SOCK_DGRAM IPPROTO_IP

 

1:wget:connect 8.8.8.8:53

 

1:wget:socket AF_INET SOCK_STREAM IPPROTO_IP

 

1:wget:connect 140.211.15.34:80

 

1:wget:fopen64 index.html.1

 

 

parent is shutting down, bye...

--tracelog

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

 

[...]

--tree

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

--version

Print program version and exit.

 

 

Example:

 

$ firejail --version

 

firejail version 0.9.27

--veth-name=name

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=dirname_or_filename

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, /media, /mnt, /opt, /srv, /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"

--writable-etc

Mount /etc directory read-write.

 

 

Example:

 

$ sudo firejail --writable-etc

--writable-var

Mount /var directory read-write.

 

 

Example:

 

$ sudo firejail --writable-var

--x11

Sandbox the application using Xpra, Xephyr 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 X11 security extension.

 

 

Xpra and Xephyr 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.

 

 

Example:

 

$ firejail --x11 --net=eth0 firefox

--x11=none

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.

--x11=xephyr

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

--x11=xorg

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

--x11=xpra

Start Xpra (http://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

--zsh

Use /usr/bin/zsh as default user shell.

 

 

Example:

 

$ firejail --zsh

DESKTOP INTEGRATION¶

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

APPARMOR¶

AppArmor support is disabled by default at compile time. Use --enable-apparmor configuration option to enable it:

 

 

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

During software install, a generic AppArmor profile file, firejail-default, is placed in /etc/apparmor.d directory. The profile needs to be loaded into the kernel by running the following command as root:

 

 

# aa-enforce firejail-default

The installed profile tries to replicate some advanced security features inspired by kernel-based Grsecurity:

 

 

- Prevent information leakage in /proc and /sys directories. The resulting filesystem is barely enough for running commands such as "top" and "ps aux".

 

 

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

 

 

- Disable D-Bus. D-Bus has long been a huge security hole, and most programs don't use it anyway. You should have no problems running Chromium or Firefox.

To enable AppArmor confinement on top of your current Firejail security features, pass --apparmor flag to Firejail command line. You can also include apparmor command in a Firejail profile file. Example:

 

 

$ firejail --apparmor firefox

FILE TRANSFER¶

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

--get=name|pid filename

Retrieve the container file and store it on the host in the current working directory. The container is specified by name or PID. This option is not available for sandboxes using --chroot.

--ls=name|pid dir_or_filename

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

--put=name|pid src-filename dest-filename

Put src-filename in sandbox container. The container is specified by name or PID. This option is not available for sandboxes using --chroot.

Examples:

 

 

$ 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

 

TRAFFIC SHAPING¶

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¶

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.

MONITORING¶

Option --list prints a list of all sandboxes. The format for each process entry is as follows: PID:USER:Command Option --tree prints the tree of processes running in the sandbox. The format for each process entry is as follows: PID:USER: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 --netstat options:

Command

Command used to start the sandbox.

CPU%

CPU usage, the sandbox share of the elapsed CPU time since the last screen update

PID

Unique process ID for the task controlling the sandbox.

Prcs

Number of processes running in sandbox, including the controlling process.

RES

Resident Memory Size (KiB), sandbox non-swapped physical memory. It is a sum of the RES values for all processes running in the sandbox.

RX(KB/s)

Network receive speed.

SHR

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.

TX(KB/s)

Network transmit speed.

Uptime

Sandbox running time in hours:minutes:seconds format.

User

The owner of the sandbox.

SECURITY PROFILES¶

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 option, the profile file is loaded. Example: 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: 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: See man 5 firejail-profile for profile file syntax information.

RESTRICTED SHELL¶

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.

EXAMPLES¶

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.

LICENSE¶

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: http://firejail.wordpress.com

SEE ALSO¶

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