jammy (8) ufw.8.gz

Provided by: ufw_0.36.1-4ubuntu0.1_all bug

NAME

       ufw - program for managing a netfilter firewall

DESCRIPTION

       This program is for managing a Linux firewall and aims to provide an easy to use interface for the user.

USAGE

       ufw [--dry-run] enable|disable|reload

       ufw [--dry-run] default allow|deny|reject [incoming|outgoing|routed]

       ufw [--dry-run] logging on|off|LEVEL

       ufw [--dry-run] reset

       ufw [--dry-run] status [verbose|numbered]

       ufw [--dry-run] show REPORT

       ufw  [--dry-run]  [delete]  [insert  NUM]  [prepend]  allow|deny|reject|limit  [in|out]  [log|log-all]  [
       PORT[/PROTOCOL] | APPNAME ] [comment COMMENT]

       ufw [--dry-run] [rule] [delete] [insert NUM] [prepend] allow|deny|reject|limit  [in|out  [on  INTERFACE]]
       [log|log-all]  [proto  PROTOCOL]  [from  ADDRESS [port PORT | app APPNAME ]] [to ADDRESS [port PORT | app
       APPNAME ]] [comment COMMENT]

       ufw [--dry-run] route [delete] [insert  NUM]  [prepend]  allow|deny|reject|limit  [in|out  on  INTERFACE]
       [log|log-all]  [proto  PROTOCOL]  [from  ADDRESS  [port PORT | app APPNAME]] [to ADDRESS [port PORT | app
       APPNAME]] [comment COMMENT]

       ufw [--dry-run] [--force] delete NUM

       ufw [--dry-run] app list|info|default|update

OPTIONS

       --version
              show program's version number and exit

       -h, --help
              show help message and exit

       --dry-run
              don't modify anything, just show the changes

       enable reloads firewall and enables firewall on boot.

       disable
              unloads firewall and disables firewall on boot

       reload reloads firewall

       default allow|deny|reject DIRECTION
              change the default policy for traffic  going  DIRECTION,  where  DIRECTION  is  one  of  incoming,
              outgoing  or  routed. Note that existing rules will have to be migrated manually when changing the
              default policy. See RULE SYNTAX for more on deny and reject.

       logging on|off|LEVEL
              toggle logging. Logged packets use the LOG_KERN syslog facility. Systems  configured  for  rsyslog
              support  may  also  log to /var/log/ufw.log. Specifying a LEVEL turns logging on for the specified
              LEVEL. The default log level is 'low'.  See LOGGING for details.

       reset  Disables and resets firewall to installation defaults. Can also give the --force option to perform
              the reset without confirmation.

       status show  status  of  firewall and ufw managed rules. Use status verbose for extra information. In the
              status output, 'Anywhere' is synonymous with 'any', 0.0.0.0/0 (IPv4) and ::/0  (IPv6).  Note  that
              when  using  status,  there  is a subtle difference when reporting interfaces. For example, if the
              following rules are added:

                ufw allow in on eth0 from 192.168.0.0/16
                ufw allow out on eth1 to 10.0.0.0/8
                ufw route allow in on eth0 out on eth1 to 10.0.0.0/8 from 192.168.0.0/16
                ufw limit 2222/tcp comment 'SSH port'

              ufw status will output:

                To                         Action      From
                --                         ------      ----
                Anywhere on eth0           ALLOW       192.168.0.0/16
                10.0.0.0/8                 ALLOW OUT   Anywhere on eth1
                10.0.0.0/8 on eth1         ALLOW FWD   192.168.0.0/16 on eth0
                Anywhere                   LIMIT       Anywhere                 # SSH port

              For the input and output rules, the interface is reported relative to the firewall  system  as  an
              endpoint,  whereas  with  route rules, the interface is reported relative to the direction packets
              flow through the firewall.

       show REPORT
              display information about the running firewall. See REPORTS

       allow ARGS
              add allow rule.  See RULE SYNTAX

       deny ARGS
              add deny rule.  See RULE SYNTAX

       reject ARGS
              add reject rule.  See RULE SYNTAX

       limit ARGS
              add limit rule.  See RULE SYNTAX

       delete RULE|NUM
              deletes the corresponding RULE

       insert NUM RULE
              insert the corresponding RULE as rule number NUM

       prepend RULE
              prepend the corresponding RULE to the top of the ruleset

RULE SYNTAX

       Users can specify rules using either a simple syntax or a full syntax. The simple syntax  only  specifies
       the port and optionally the protocol to be allowed or denied on the host.

       Both  syntaxes  support  specifying  a  comment  for the rule. For existing rules, specifying a different
       comment updates the comment and specifying '' removes the comment.

       Example rules using the simple syntax:

         ufw allow 53

       This rule will allow tcp and udp port 53 to any address on this  host.  To  specify  a  protocol,  append
       '/protocol' to the port. For example:

         ufw allow 25/tcp

       This  will  allow tcp port 25 to any address on this host. ufw will also check /etc/services for the port
       and protocol if specifying a service by name.  Eg:

         ufw allow smtp

       ufw supports both ingress and egress filtering and users may optionally specify a direction of either  in
       or out for either incoming or outgoing traffic. If no direction is supplied, the rule applies to incoming
       traffic. Eg:

         ufw allow in http
         ufw reject out smtp
         ufw reject telnet comment 'telnet is unencrypted'

       Users can also use a fuller syntax, specifying the source  and  destination  addresses  and  ports.  This
       syntax is loosely based on OpenBSD's PF syntax. For example:

         ufw deny proto tcp to any port 80

       This will deny all traffic to tcp port 80 on this host. Another example:

         ufw deny proto tcp from 10.0.0.0/8 to 192.168.0.1 port 25

       This will deny all traffic from the RFC1918 Class A network to tcp port 25 with the address 192.168.0.1.

         ufw deny proto tcp from 2001:db8::/32 to any port 25

       This  will deny all traffic from the IPv6 2001:db8::/32 to tcp port 25 on this host. IPv6 must be enabled
       in /etc/default/ufw for IPv6 firewalling to work.

         ufw deny in on eth0 to 224.0.0.1 proto igmp

       This will deny all igmp traffic to 224.0.0.1 on the eth0 interface.

         ufw allow in on eth0 to 192.168.0.1 proto gre

       This will allow all gre traffic to 192.168.0.1 on the eth0 interface.

         ufw allow proto tcp from any to any port 80,443,8080:8090 comment 'web app'

       The above will allow all traffic to tcp ports 80, 443 and 8080-8090 inclusive and adds a comment for  the
       rule.  When  specifying multiple ports, the ports list must be numeric, cannot contain spaces and must be
       modified as a whole. Eg, in the above example you cannot later try to delete just  the  '443'  port.  You
       cannot specify more than 15 ports (ranges count as 2 ports, so the port count in the above example is 4).

       ufw  supports  several  different  protocols.  The  following  are valid in any rule and enabled when the
       protocol is not specified:

         tcp
         udp

       The following have certain restrictions and are not enabled when the protocol is not specified:

         ah      valid without port number
         esp     valid without port number
         gre     valid without port number
         ipv6    valid for IPv4 addresses and without port number
         igmp    valid for IPv4 addresses and without port number

       Rules  for  traffic  not  destined  for  the  host  itself  but  instead  for  traffic  that  should   be
       routed/forwarded  through  the  firewall  should specify the route keyword before the rule (routing rules
       differ significantly from PF syntax and instead take into account netfilter FORWARD  chain  conventions).
       For example:

         ufw route allow in on eth1 out on eth2

       This will allow all traffic routed to eth2 and coming in on eth1 to traverse the firewall.

         ufw route allow in on eth0 out on eth1 to 12.34.45.67 port 80 proto tcp

       This  rule  allows  any  packets coming in on eth0 to traverse the firewall out on eth1 to tcp port 80 on
       12.34.45.67.

       In addition to routing rules and policy, you must also setup IP forwarding.  This may be done by  setting
       the following in /etc/ufw/sysctl.conf:

         net/ipv4/ip_forward=1
         net/ipv6/conf/default/forwarding=1
         net/ipv6/conf/all/forwarding=1

       then restarting the firewall:

         ufw disable
         ufw enable

       Be  aware  that  setting  kernel  tunables  is  operating  system specific and ufw sysctl settings may be
       overridden. See the sysctl manual page for details.

       ufw supports connection rate limiting, which is useful for protecting against brute-force login  attacks.
       When  a  limit  rule  is  used, ufw will normally allow the connection but will deny connections if an IP
       address   attempts    to    initiate    6    or    more    connections    within    30    seconds.    See
       http://www.debian-administration.org/articles/187 for details. Typical usage is:

         ufw limit ssh/tcp

       Sometimes  it  is  desirable  to  let  the  sender  know when traffic is being denied, rather than simply
       ignoring it. In these cases, use reject instead of deny.  For example:

         ufw reject auth

       By default, ufw will apply rules to all  available  interfaces.  To  limit  this,  specify  DIRECTION  on
       INTERFACE,  where  DIRECTION  is one of in or out (interface aliases are not supported).  For example, to
       allow all new incoming http connections on eth0, use:

         ufw allow in on eth0 to any port 80 proto tcp

       To delete a rule, simply prefix the original rule with delete with  or  without  the  rule  comment.  For
       example, if the original rule was:

         ufw deny 80/tcp

       Use this to delete it:

         ufw delete deny 80/tcp

       You  may also specify the rule by NUM, as seen in the status numbered output. For example, if you want to
       delete rule number '3', use:

         ufw delete 3

       If you have IPv6 enabled and are deleting a generic rule that applies to both  IPv4  and  IPv6  (eg  'ufw
       allow  22/tcp'),  deleting  by  rule  number will delete only the specified rule. To delete both with one
       command, prefix the original rule with delete.

       To insert a rule, specify the new rule as normal, but prefix the rule with the rule number to insert. For
       example, if you have four rules, and you want to insert a new rule as rule number three, use:

         ufw insert 3 deny to any port 22 from 10.0.0.135 proto tcp

       Similarly, to add a rule before all other rules matching the rule's IP type, use the prepend rule:

         ufw prepend deny from 1.2.3.4

       This is particularly useful for dynamic firewalls as found in an IPS.  Importantly, if the specified rule
       is an IPv4 rule, it will be prepended before all other IPv4 rules. If it is an  IPv6  rule,  it  will  be
       prepended before any IPv6 rules.

       To see a list of numbered rules, use:

         ufw status numbered

       ufw  supports  per  rule  logging.  By  default,  no  logging  is performed when a packet matches a rule.
       Specifying log will log all new connections matching the rule, and log-all will log all packets  matching
       the rule.  For example, to allow and log all new ssh connections, use:

         ufw allow log 22/tcp

       See LOGGING for more information on logging.

EXAMPLES

       Deny all access to port 53:

         ufw deny 53

       Allow all access to tcp port 80:

         ufw allow 80/tcp

       Allow all access from RFC1918 networks to this host:

         ufw allow from 10.0.0.0/8
         ufw allow from 172.16.0.0/12
         ufw allow from 192.168.0.0/16

       Deny access to udp port 514 from host 1.2.3.4:

         ufw deny proto udp from 1.2.3.4 to any port 514

       Allow access to udp 1.2.3.4 port 5469 from 1.2.3.5 port 5469:

         ufw allow proto udp from 1.2.3.5 port 5469 to 1.2.3.4 port 5469

REMOTE MANAGEMENT

       When  running  ufw enable or starting ufw via its initscript, ufw will flush its chains. This is required
       so ufw can maintain a consistent state, but it may drop existing connections (eg ssh). ufw  does  support
       adding rules before enabling the firewall, so administrators can do:

         ufw allow proto tcp from any to any port 22

       before  running  'ufw  enable'.  The  rules  will  still  be flushed, but the ssh port will be open after
       enabling the firewall. Please note that once ufw is 'enabled', ufw will not flush the chains when  adding
       or  removing  rules (but will when modifying a rule or changing the default policy). By default, ufw will
       prompt when enabling the firewall while running under ssh. This can be disabled  by  using  'ufw  --force
       enable'.

APPLICATION INTEGRATION

       ufw  supports application integration by reading profiles located in /etc/ufw/applications.d. To list the
       names of application profiles known to ufw, use:

         ufw app list

       Users can specify an application name when adding a rule (quoting any profile  names  with  spaces).  For
       example, when using the simple syntax, users can use:

         ufw allow <name>

       Or for the extended syntax:

         ufw allow from 192.168.0.0/16 to any app <name>

       You should not specify the protocol with either syntax, and with the extended syntax, use app in place of
       the port clause.

       Details on the firewall profile for a given application can be seen with:

         ufw app info <name>

       where '<name>' is one of the applications seen with the app list command.  Users may also specify all  to
       see the profiles for all known applications.

       Syntax for the application profiles is a simple .INI format:

         [<name>]
         title=<title>
         description=<description>
         ports=<ports>

       The  'ports'  field may specify a '|'-separated list of ports/protocols where the protocol is optional. A
       comma-separated list or a range (specified with 'start:end') may also be used to specify multiple  ports,
       in which case the protocol is required. For example:

         [SomeService]
         title=Some title
         description=Some description
         ports=12/udp|34|56,78:90/tcp

       In the above example, 'SomeService' may be used in app rules and it specifies UDP port 12, TCP and UDP on
       port 34 and TCP ports 56 and 78-90 inclusive.

       After creating or editing an application profile, users can run:

         ufw app update <name>

       This command will automatically update the firewall with updated profile information.  If  specify  'all'
       for  name, then all the profiles will be updated.  To update a profile and add a new rule to the firewall
       automatically, users can run:

         ufw app update --add-new <name>

       The behavior of the update --add-new command can be configured using:

         ufw app default <policy>

       The default application policy is skip, which means that the update --add-new command  will  do  nothing.
       Users may also specify a policy of allow or deny so the update --add-new command may automatically update
       the firewall.  WARNING: it may be a security to risk to  use  a  default  allow  policy  for  application
       profiles. Carefully consider the security ramifications before using a default allow policy.

LOGGING

       ufw  supports  multiple  logging  levels.  ufw  defaults  to  a  loglevel of 'low' when a loglevel is not
       specified. Users may specify a loglevel with:

         ufw logging LEVEL

       LEVEL may be 'off', 'low', 'medium', 'high' and 'full'. Log levels are defined as:

       off    disables ufw managed logging

       low    logs all blocked packets not matching the defined policy (with rate limiting), as well as  packets
              matching logged rules

       medium log  level low, plus all allowed packets not matching the defined policy, all INVALID packets, and
              all new connections.  All logging is done with rate limiting.

       high   log level medium (without rate limiting), plus all packets with rate limiting

       full   log level high without rate limiting

       Loglevels above medium generate a lot of logging output, and may quickly  fill  up  your  disk.  Loglevel
       medium may generate a lot of logging output on a busy system.

       Specifying 'on' simply enables logging at log level 'low' if logging is currently not enabled.

REPORTS

       The  following  reports  are  supported.  Each  is based on the live system and with the exception of the
       listening report, is in raw iptables format:

         raw
         builtins
         before-rules
         user-rules
         after-rules
         logging-rules
         listening
         added

       The raw report shows the complete firewall, while the others show a subset of what is in the raw report.

       The listening report will display the ports on the live system in the listening state  for  tcp  and  the
       open  state for udp, along with the address of the interface and the executable listening on the port. An
       '*' is used in place of the address of the interface when the executable is bound to  all  interfaces  on
       that  port.  Following this information is a list of rules which may affect connections on this port. The
       rules are listed in the order they are evaluated by the kernel, and the first  match  wins.  Please  note
       that the default policy is not listed and tcp6 and udp6 are shown only if IPV6 is enabled.

       The  added report displays the list of rules as they were added on the command-line. This report does not
       show the status of the running firewall (use 'ufw status' instead). Because rules are normalized by  ufw,
       rules  may  look different than the originally added rule. Also, ufw does not record command ordering, so
       an equivalent ordering is used which lists IPv6-only rules after other rules.

NOTES

       On installation, ufw is disabled with a default incoming policy of deny,  a  default  forward  policy  of
       deny, and a default outgoing policy of allow, with stateful tracking for NEW connections for incoming and
       forwarded connections.  In addition to the above, a default  ruleset  is  put  in  place  that  does  the
       following:

       - DROP packets with RH0 headers

       - DROP INVALID packets

       - ACCEPT certain icmp packets (INPUT and FORWARD): destination-unreachable, source-quench, time-exceeded,
       parameter-problem, and echo-request for  IPv4.  destination-unreachable,  packet-too-big,  time-exceeded,
       parameter-problem, and echo-request for IPv6.

       - ACCEPT icmpv6 packets for stateless autoconfiguration (INPUT)

       - ACCEPT ping replies from IPv6 link-local (ffe8::/10) addresses (INPUT)

       - ACCEPT DHCP client traffic (INPUT)

       - DROP non-local traffic (INPUT)

       -  ACCEPT  mDNS (zeroconf/bonjour/avahi 224.0.0.251 for IPv4 and ff02::fb for IPv6) for service discovery
       (INPUT)

       - ACCEPT UPnP (239.255.255.250 for IPv4 and ff02::f for IPv6) for service discovery (INPUT)

       Rule ordering is important and the first match wins. Therefore when adding rules, add the  more  specific
       rules first with more general rules later.

       ufw  is  not  intended  to provide complete firewall functionality via its command interface, but instead
       provides an easy way to add or remove simple rules.

       The status command shows basic information about the state of the firewall, as well as rules managed  via
       the  ufw  command.  It does not show rules from the rules files in /etc/ufw. To see the complete state of
       the firewall, users can ufw show raw.  This displays the filter, nat, mangle and raw tables using:

         iptables -n -L -v -x -t <table>
         ip6tables -n -L -v -x -t <table>

       See the iptables and ip6tables documentation for more details.

       If the default policy is set to REJECT, ufw may interfere with rules added outside of the ufw  framework.
       See README for details.

       IPV6  is  allowed  by  default.  To  change  this  behavior  to  only accept IPv6 traffic on the loopback
       interface, set IPV6 to 'no' in /etc/default/ufw and reload ufw. When IPv6 is  enabled,  you  may  specify
       rules  in  the  same  way as for IPv4 rules, and they will be displayed with ufw status. Rules that match
       both IPv4 and IPv6 addresses apply to both IP versions. For example, when IPv6 is enabled, the  following
       rule will allow access to port 22 for both IPv4 and IPv6 traffic:

         ufw allow 22

       IPv6 over IPv4 tunnels and 6to4 are supported by using the 'ipv6' protocol ('41'). This protocol can only
       be used with the full syntax. For example:

         ufw allow to 10.0.0.1 proto ipv6
         ufw allow to 10.0.0.1 from 10.4.0.0/16 proto ipv6

       IPSec is supported by using the 'esp' ('50') and 'ah' ('51') protocols. These protocols can only be  used
       with the full syntax. For example:

         ufw allow to 10.0.0.1 proto esp
         ufw allow to 10.0.0.1 from 10.4.0.0/16 proto esp
         ufw allow to 10.0.0.1 proto ah
         ufw allow to 10.0.0.1 from 10.4.0.0/16 proto ah

       In  addition  to the command-line interface, ufw also provides a framework which allows administrators to
       modify default behavior as well as take full advantage of netfilter. See the  ufw-framework  manual  page
       for more information.

SEE ALSO

       ufw-framework(8),   iptables(8),   ip6tables(8),  iptables-restore(8),  ip6tables-restore(8),  sysctl(8),
       sysctl.conf(5)

AUTHOR

       ufw is Copyright 2008-2021, Canonical Ltd.