iptables

Collection Note

This module is part of the ansible.builtin collection. To install the collection, use:

ansible-galaxy collection install ansible.builtin

Added in version 2.0.

Synopsis

• M(ansible.builtin.iptables) is used to set up, maintain, and inspect the tables of IP packet filter rules in the Linux kernel.
• This module does not handle the saving and/or loading of rules, but rather only manipulates the current rules that are present in memory. This is the same as the behaviour of the C(iptables) and C(ip6tables) command which this module uses internally.

Parameters

Parameter	Defaults / Choices	Comments
action str	Default: append Choices: append, insert	Whether the rule should be appended at the bottom or inserted at the top. If the rule already exists the chain will not be modified. Version Added: 2.2
chain str		Specify the iptables chain to modify. This could be a user-defined chain or one of the standard iptables chains, like V(INPUT), V(FORWARD), V(OUTPUT), V(PREROUTING), V(POSTROUTING), V(SECMARK) or V(CONNSECMARK).
chain_management bool		If V(true) and O(state) is V(present), the chain will be created if needed. If V(true) and O(state) is V(absent), the chain will be deleted if the only other parameter passed are O(chain) and optionally O(table). Version Added: 2.13
comment str		This specifies a comment that will be added to the rule.
ctstate list / elements=str		A list of the connection states to match in the conntrack module. Possible values are V(INVALID), V(NEW), V(ESTABLISHED), V(RELATED), V(UNTRACKED), V(SNAT), V(DNAT).
destination str		Destination specification. Address can be either a network name, a hostname, a network IP address (with /mask), or a plain IP address. Hostnames will be resolved once only, before the rule is submitted to the kernel. Please note that specifying any name to be resolved with a remote query such as DNS is a really bad idea. The mask can be either a network mask or a plain number, specifying the number of 1's at the left side of the network mask. Thus, a mask of 24 is equivalent to 255.255.255.0. A V(!) argument before the address specification inverts the sense of the address.
destination_port str		Destination port or port range specification. This can either be a service name or a port number. An inclusive range can also be specified, using the format first:last. If the first port is omitted, '0' is assumed; if the last is omitted, '65535' is assumed. If the first port is greater than the second one they will be swapped. This is only valid if the rule also specifies one of the following protocols: tcp, udp, dccp or sctp.
destination_ports list / elements=str		This specifies multiple destination port numbers or port ranges to match in the multiport module. It can only be used in conjunction with the protocols tcp, udp, udplite, dccp and sctp. Version Added: 2.11
dst_range str		Specifies the destination IP range to match in the iprange module. Version Added: 2.8
flush bool		Flushes the specified table and chain of all rules. If no chain is specified then the entire table is purged. Ignores all other parameters. Version Added: 2.2
fragment str		This means that the rule only refers to second and further fragments of fragmented packets. Since there is no way to tell the source or destination ports of such a packet (or ICMP type), such a packet will not match any rules which specify them. When the "!" argument precedes the fragment argument, the rule will only match head fragments, or unfragmented packets.
gateway str		This specifies the IP address of the host to send the cloned packets. This option is only valid when O(jump=TEE). Version Added: 2.8
gid_owner str		Specifies the GID or group to use in the match by owner rule. Version Added: 2.9
goto str		This specifies that the processing should continue in a user-specified chain. Unlike the jump argument return will not continue processing in this chain but instead in the chain that called us via jump.
icmp_type str		This allows specification of the ICMP type, which can be a numeric ICMP type, type/code pair, or one of the ICMP type names shown by the command C(iptables -p icmp -h). Version Added: 2.2
in_interface str		Name of an interface via which a packet was received (only for packets entering the V(INPUT), V(FORWARD) and V(PREROUTING) chains). When the V(!) argument is used before the interface name, the sense is inverted. If the interface name ends in a V(+), then any interface which begins with this name will match. If this option is omitted, any interface name will match.
ip_version str	Default: ipv4 Choices: ipv4, ipv6	Which version of the IP protocol this rule should apply to.
jump str		This specifies the target of the rule; i.e., what to do if the packet matches it. The target can be a user-defined chain (other than the one this rule is in), one of the special builtin targets that decide the fate of the packet immediately, or an extension (see EXTENSIONS below). If this option is omitted in a rule (and the goto parameter is not used), then matching the rule will have no effect on the packet's fate, but the counters on the rule will be incremented.
limit str		Specifies the maximum average number of matches to allow per second. The number can specify units explicitly, using C(/second), C(/minute), C(/hour) or C(/day), or parts of them (so V(5/second) is the same as V(5/s)).
limit_burst str		Specifies the maximum burst before the above limit kicks in. Version Added: 2.1
log_level str	Choices: 0, 1, 2, 3, 4, 5, 6, 7, emerg, alert, crit, error, warning, notice, info, debug	Logging level according to the syslogd-defined priorities. The value can be strings or numbers from 1-8. This parameter is only applicable if O(jump=LOG). Version Added: 2.8
log_prefix str		Specifies a log text for the rule. Only makes sense with a LOG jump. Version Added: 2.5
match list / elements=str		Specifies a match to use, that is, an extension module that tests for a specific property. The set of matches makes up the condition under which a target is invoked. Matches are evaluated first to last if specified as an array and work in short-circuit fashion, in other words if one extension yields false, the evaluation will stop.
match_set str		Specifies a set name that can be defined by ipset. Must be used together with the O(match_set_flags) parameter. When the V(!) argument is prepended then it inverts the rule. Uses the iptables set extension. Version Added: 2.11
match_set_flags str	Choices: src, dst, src,dst, dst,src, dst,dst, src,src	Specifies the necessary flags for the match_set parameter. Must be used together with the O(match_set) parameter. Uses the iptables set extension. Choices V(dst,dst) and V(src,src) added in version 2.17. Version Added: 2.11
numeric bool		This parameter controls the running of the list -action of iptables, which is used internally by the module. Does not affect the actual functionality. Use this if iptables hang when creating a chain or altering policy. If V(true), then iptables skips the DNS-lookup of the IP addresses in a chain when it uses the list -action. Listing is used internally for example when setting a policy or creating a chain. Version Added: 2.15
out_interface str		Name of an interface via which a packet is going to be sent (for packets entering the V(FORWARD), V(OUTPUT) and V(POSTROUTING) chains). When the V(!) argument is used before the interface name, the sense is inverted. If the interface name ends in a V(+), then any interface which begins with this name will match. If this option is omitted, any interface name will match.
policy str	Choices: ACCEPT, DROP, QUEUE, RETURN	Set the policy for the chain to the given target. Only built-in chains can have policies. This parameter requires the O(chain) parameter. If you specify this parameter, all other parameters will be ignored. This parameter is used to set the default policy for the given O(chain). Do not confuse this with O(jump) parameter. Version Added: 2.2
protocol str		The protocol of the rule or of the packet to check. The specified protocol can be one of V(tcp), V(udp), V(udplite), V(icmp), V(ipv6-icmp) or V(icmpv6), V(esp), V(ah), V(sctp) or the special keyword V(all), or it can be a numeric value, representing one of these protocols or a different one. A protocol name from C(/etc/protocols) is also allowed. A V(!) argument before the protocol inverts the test. The number zero is equivalent to all. V(all) will match with all protocols and is taken as default when this option is omitted.
reject_with str		Specifies the error packet type to return while rejecting. It implies C(jump=REJECT). Version Added: 2.1
rule_num str		Insert the rule as the given rule number. This works only with O(action=insert). Version Added: 2.5
set_counters str		This enables the administrator to initialize the packet and byte counters of a rule (during V(INSERT), V(APPEND), V(REPLACE) operations).
set_dscp_mark str		This allows specifying a DSCP mark to be added to packets. It takes either an integer or hex value. If the parameter is set, O(jump) is set to V(DSCP). Mutually exclusive with O(set_dscp_mark_class). Version Added: 2.1
set_dscp_mark_class str		This allows specifying a predefined DiffServ class which will be translated to the corresponding DSCP mark. If the parameter is set, O(jump) is set to V(DSCP). Mutually exclusive with O(set_dscp_mark). Version Added: 2.1
source str		Source specification. Address can be either a network name, a hostname, a network IP address (with /mask), or a plain IP address. Hostnames will be resolved once only, before the rule is submitted to the kernel. Please note that specifying any name to be resolved with a remote query such as DNS is a really bad idea. The mask can be either a network mask or a plain number, specifying the number of 1's at the left side of the network mask. Thus, a mask of 24 is equivalent to 255.255.255.0. A V(!) argument before the address specification inverts the sense of the address.
source_port str		Source port or port range specification. This can either be a service name or a port number. An inclusive range can also be specified, using the format C(first:last). If the first port is omitted, V(0) is assumed; if the last is omitted, V(65535) is assumed. If the first port is greater than the second one they will be swapped.
src_range str		Specifies the source IP range to match the iprange module. Version Added: 2.8
state str	Default: present Choices: absent, present	Whether the rule should be absent or present.
syn str	Default: ignore Choices: ignore, match, negate	This allows matching packets that have the SYN bit set and the ACK and RST bits unset. When negated, this matches all packets with the RST or the ACK bits set. Version Added: 2.5
table str	Default: filter Choices: filter, nat, mangle, raw, security	This option specifies the packet matching table on which the command should operate. If the kernel is configured with automatic module loading, an attempt will be made to load the appropriate module for that table if it is not already there.
tcp_flags dict		TCP flags specification. O(tcp_flags) expects a dict with the two keys C(flags) and C(flags_set). Version Added: 2.4
tcp_flags.flags		List of flags you want to examine.
tcp_flags.flags_set		Flags to be set.
to_destination str		This specifies a destination address to use with O(ctstate=DNAT). Without this, the destination address is never altered. Version Added: 2.1
to_ports str		This specifies a destination port or range of ports to use, without this, the destination port is never altered. This is only valid if the rule also specifies one of the protocol V(tcp), V(udp), V(dccp) or V(sctp).
to_source str		This specifies a source address to use with O(ctstate=SNAT). Without this, the source address is never altered. Version Added: 2.2
uid_owner str		Specifies the UID or username to use in the match by owner rule. From Ansible 2.6 when the C(!) argument is prepended then the it inverts the rule to apply instead to all users except that one specified. Version Added: 2.1
wait str		Wait N seconds for the xtables lock to prevent multiple instances of the program from running concurrently. Version Added: 2.10

Notes

Note

• This module just deals with individual rules. If you need advanced chaining of rules the recommended way is to template the iptables restore file.

Examples

- name: Block specific IP
  ansible.builtin.iptables:
    chain: INPUT
    source: 8.8.8.8
    jump: DROP
  become: yes

- name: Forward port 80 to 8600
  ansible.builtin.iptables:
    table: nat
    chain: PREROUTING
    in_interface: eth0
    protocol: tcp
    match: tcp
    destination_port: 80
    jump: REDIRECT
    to_ports: 8600
    comment: Redirect web traffic to port 8600
  become: yes

- name: Allow related and established connections
  ansible.builtin.iptables:
    chain: INPUT
    ctstate: ESTABLISHED,RELATED
    jump: ACCEPT
  become: yes

- name: Allow new incoming SYN packets on TCP port 22 (SSH)
  ansible.builtin.iptables:
    chain: INPUT
    protocol: tcp
    destination_port: 22
    ctstate: NEW
    syn: match
    jump: ACCEPT
    comment: Accept new SSH connections.

- name: Match on IP ranges
  ansible.builtin.iptables:
    chain: FORWARD
    src_range: 192.168.1.100-192.168.1.199
    dst_range: 10.0.0.1-10.0.0.50
    jump: ACCEPT

- name: Allow source IPs defined in ipset "admin_hosts" on port 22
  ansible.builtin.iptables:
    chain: INPUT
    match_set: admin_hosts
    match_set_flags: src
    destination_port: 22
    jump: ALLOW

- name: Tag all outbound tcp packets with DSCP mark 8
  ansible.builtin.iptables:
    chain: OUTPUT
    jump: DSCP
    table: mangle
    set_dscp_mark: 8
    protocol: tcp

- name: Tag all outbound tcp packets with DSCP DiffServ class CS1
  ansible.builtin.iptables:
    chain: OUTPUT
    jump: DSCP
    table: mangle
    set_dscp_mark_class: CS1
    protocol: tcp

# Create the user-defined chain ALLOWLIST
- iptables:
    chain: ALLOWLIST
    chain_management: true

# Delete the user-defined chain ALLOWLIST
- iptables:
    chain: ALLOWLIST
    chain_management: true
    state: absent

- name: Insert a rule on line 5
  ansible.builtin.iptables:
    chain: INPUT
    protocol: tcp
    destination_port: 8080
    jump: ACCEPT
    action: insert
    rule_num: 5

# Think twice before running following task as this may lock target system
- name: Set the policy for the INPUT chain to DROP
  ansible.builtin.iptables:
    chain: INPUT
    policy: DROP

- name: Reject tcp with tcp-reset
  ansible.builtin.iptables:
    chain: INPUT
    protocol: tcp
    reject_with: tcp-reset
    ip_version: ipv4

- name: Set tcp flags
  ansible.builtin.iptables:
    chain: OUTPUT
    jump: DROP
    protocol: tcp
    tcp_flags:
      flags: ALL
      flags_set:
        - ACK
        - RST
        - SYN
        - FIN

- name: Iptables flush filter
  ansible.builtin.iptables:
    chain: "{{ item }}"
    flush: yes
  with_items:  [ 'INPUT', 'FORWARD', 'OUTPUT' ]

- name: Iptables flush nat
  ansible.builtin.iptables:
    table: nat
    chain: '{{ item }}'
    flush: yes
  with_items: [ 'INPUT', 'OUTPUT', 'PREROUTING', 'POSTROUTING' ]

- name: Log packets arriving into an user-defined chain
  ansible.builtin.iptables:
    chain: LOGGING
    action: append
    state: present
    limit: 2/second
    limit_burst: 20
    log_prefix: "IPTABLES:INFO: "
    log_level: info

- name: Allow connections on multiple ports
  ansible.builtin.iptables:
    chain: INPUT
    protocol: tcp
    destination_ports:
      - "80"
      - "443"
      - "8081:8083"
    jump: ACCEPT

Authors

• Linus Unnebäck (@linusu) Linus@folkdatorn.se
• Sébastien Da Rocha (@sebastiendarocha)