ip_allow.yaml¶

The ip_allow.yaml file controls client access to Traffic Server and Traffic Server connections to upstream servers. This control is specified via rules. Each rule has:

A direction (inbound or out).
A range of IP addresses or an IP category to which the rule applies.
An action, either accept or deny.
A list of HTTP methods.

Inbound rules control access to Traffic Server from user agents. Outbound rules control access to upstream destinations from Traffic Server. The IP addresses always apply to the remote address for Traffic Server. That is, the user agent IP address for inbound rules and the upstream destination address for outbound rules. The rule can apply at the connection level or just to specific methods.

Traffic Server can be updated for changes to the rules in ip_allow.yaml file, by running the traffic_ctl config reload.

Format¶

ip_allow.yaml is YAML format. The default configuration is:

# YAML
ip_allow:
  - apply: in
    ip_addrs: 127.0.0.1
    action: allow
    methods: ALL
  - apply: in
    ip_addrs: ::1
    action: allow
    methods: ALL
  - apply: in
    ip_addrs: 0/0
    action: deny
    methods:
      - PURGE
      - PUSH
      - DELETE
      - TRACE
  - apply: in
    ip_addrs: ::/0
    action: deny
    methods:
      - PURGE
      - PUSH
      - DELETE
      - TRACE

Each rule is a mapping. The YAML data must have a top level key of "ip_allow" and its value must be a mapping or a sequence of mappings, each of those being one rule.

The keys in a rule are:

apply

This is where the rule is applied, either in or out. Inbound application means the rule is applied to inbound user agent connections. Outbound application means the rule is applied to outbound connections from Traffic Server to an upstream destination. This is a required key.

ip_addrs

IP addresses to match for the rule to be applied. This can be either an address range or an array of address ranges. Either this or ip_categories are required keys for a rule.

ip_categories

A user defined string identifying a category of IP addresses relevant to a particular network. For example, ACME_INTERNAL might represent the set of IP addresses for hosts within a company's network. ACME_EXTERNAL might represet hosts belonging to the company's network, but which are outside the company's firewall. ACME_ALL could be used to represent the set of both of these categories. Multiple categories can be specified as an array of strings.

The set of IP ranges belonging to each category is specified via the separate ip_categories root level node. The ip_allow.yaml parser also supports supplying the IP categories via an external file specified with the proxy.config.cache.ip_categories.filename configuration.

Either this or ip_addrs are required keys for a rule.

action

The action describing the behavior of the rule. This can be either set_allow or set_deny. set_allow provides a list of allowed methods, while all requests with other methods are denied. set_deny provides a list of denied methods, while all requests with other methods are allowed. This is a required key.

注釈

Prior to Traffic Server 10.x, these actions were named allow and deny. In order to bring alignment to the action names in remap ACL actions (see ACL Filters for more details), these have been renamed to set_allow and set_deny. If proxy.config.url_remap.acl_behavior_policy is set to 0, which is the default, the old allow and deny actions are still supported in order to provide backwards compatibility to Traffic Server 9.x ip_allow.yaml files. If it is set to 1, then the use of allow and deny will result in a fatal error with a message asking the user to use set_allow and set_deny instead.

methods: This is optional. If not present, the rule action applies to all methods. If present, the rule action is applied to connections using those methods and its opposite to all other connections. The keyword "ALL" means all methods, making the specification of any other method redundant. All methods comparisons are case insensitive. This is an optional key.

An IP address range for ip_addrs or ip_categories can be specified in several ways. A range is always IPv4 or IPv6, it is not allowed to have a range that contains addresses from different IP address families.

A single address, which specifies a range of size 1, e.g. "127.0.0.1".
A minimum and maximum address separated by a dash, e.g. "10.1.0.0-10.1.255.255".
A CIDR based value, e.g. "10.1.0.0/16", which is a range containing exactly the specified network.

A rule must have the apply, ip_addrs, and action keys. Rules match based on IP addresses only and are then applied to all matching sessions. If the rule is an allow rule, the specified methods are allowed and all other methods are denied. If the rule is a deny rule, the specified methods are denied and all other methods are allowed.

For example, from the default configuration, the rule for 127.0.0.1 is allow with all methods. Therefore an inbound connection from the loopback address (127.0.0.1) is allowed to use any method. The general IPv4 rule, covering all IPv4 address, is a deny rule and therefore when it matches the methods "PURGE", "PUSH", "DELETE", and "TRACE", these methods are denied and any other method is allowed.

The rules are matched in order, by IP address, therefore the general IPv4 rule does not apply to the loopback address because the latter is matched first.

A major difference in application between in and out rules is that by default, inbound connections are denied and therefore if there is no rule that matches, the connection is denied. Outbound rules allow by default, so the absence of rules in the default configuration enables all methods for all outbound connections.

注釈

Be aware that ip_allow rules will not, and indeed cannot, be applied to TLS connections which are tunneled via tunnel_route to the upstream target. Such connections are not decrypted and thus are not processed by Traffic Server. This applies as well to TLS connections which are forwarded via forward_route since, while those are decrypted, they are not processed by Traffic Server. For details, see SNI Routing and sni.yaml.

Timing¶

IP allow rules are applied at different stages, depending on the type of rule:

On connection accept: At the beginning of accepting a connection, if the source IP address matches an in rule and the rule denies all methods from this client (meaning that all transactions from the client are denied), the connection is immediately closed by Traffic Server. The idea is that since the administrator wants to deny all transactions from the client, Traffic Server should just reject any connection from the client and not even process data from it. Note that this means that for these all-method rules, no transactions are ever processed by Traffic Server, and thus there will be no transaction log entries for these denied connections.
Post remap: in rules that are not all-method rules (meaning they apply only to certain methods) are processed for each transaction after the client headers are parsed and remap is applied. Processing the rules post-remap allows for remap ACL modifications (see Remap ACL Filters).
Preceding server connect: out rules are applied after DNS resolution of the upstream server but before the connection is established.

Examples¶

The following example enables all clients access:

apply: in
ip_addrs: 0.0.0.0-255.255.255.255
action: allow

The following example allows access to all clients on addresses in a subnet:

apply: in
ip_addrs: 123.12.3.000-123.12.3.123
action: allow

The following example denies access all clients on addresses in a subnet:

apply: in
ip_addrs: 123.45.6.0-123.45.6.123
action: deny

If the entire subnet were to be denied, that would be:

apply: in
ip_addrs: 123.45.6.0/24
action: deny

The following example allows any method to any upstream servers:

apply: out
ip_addrs: 0.0.0.0-255.255.255.255
action: allow

Alternatively this can be done with:

apply: out
ip_addrs: 0/0
action: allow

Or also by having no rules at all, as outbound by default is allow.

The following example denies to access all servers on a specific subnet:

apply: out
ip_addr: 10.0.0.0-10.0.255.255
action: deny

Alternatively:

apply: out
ip_addrs: 10.0.0.0/16
action: deny

The ip_addrs can be an array of ranges, so that:

- apply: in
  ip_addrs: 10.0.0.0/8
  action: deny
- apply: in
  ip_addrs: 172.16.0.0/20
  action: deny
- apply: in
  ip_addrs: 192.168.1.0/24
  action: deny

can be done more simply as:

apply: in
ip_addrs:
  - 10.0.0.0/8
  - 172.16.0.0/20
  - 192.168.1.0/24
action: deny

If the goal is to allow only GET and HEAD requests to those servers, it would be:

apply: out
ip_addrs: 10.0.0.0/16
methods: [ GET, HEAD ]
action: allow

Alternatively:

apply: out
ip_addrs: 10.0.0.0/16
methods:
- GET
- HEAD
action: allow

This will match the IP address for the target servers on the outbound connection. Then, if the method is GET or HEAD the connection will be allowed, otherwise the connection will be denied.

For the purposes of illustration, here is the default configuration in compact form:

ip_allow: [
  { apply: in, ip_addrs: 127.0.0.1, action: allow },
  { apply: in, ip_addrs: "::1", action: allow },
  { apply: in, ip_addrs: 0/0, action: deny, methods: [ PURGE, PUSH, DELETE, TRACE ] },
  { apply: in, ip_addrs: "::/0", action: deny, methods: [ PURGE, PUSH, DELETE, TRACE ] }
  ]

The following example demonstrates how to use ip_categories. In this example, the ip_categories is ACME_INTERNAL which is presumably associated with trusted internal IP addresses and thus are allowed to POST and DELETE resources.

Note this example demonstrates that it is OK to mix ip_categories and ip_addrs rules in a single ip_allow.yaml file. In this case all other IPv4 addresses not matched on ACME_INTERNAL match on 0/0 and can only perform GET and HEAD requests:

- apply: in
  ip_categories: ACME_INTERNAL
  action: allow
  methods:
    - GET
    - HEAD
    - POST
    - DELETE
- apply: in
  ip_addrs: 0/0
  action: allow
  methods:
    - GET
    - HEAD

The set of IP addresses associated with ACME_INTERNAL can be specified using the ip_categories node like so:

ip_categories:
  - name: ACME_INTERNAL
    ip_addrs:
      - 10.0.0.0/8
      - 172.16.0.0/20
      - 192.168.1.0/24

ip_allow:
  - apply: in
  # ...

The ip_categories node will generally be at the start of the ip_allow.yaml file. Alternatively, the same content with the ip_categories root node can exist in a separate file specified with the proxy.config.cache.ip_categories.filename configuration.

注釈

For ATS 9.0, this file is (almost) backwards compatible. If the first line is a single '#' character, or contains only "# ats", then the file will be read in the version 8.0 format. This is true for the default format and so if that has not been changed it should still work. This allows a grace period before ATS 10.0 which will drop the old format entirely.