Provided by: trafficserver_9.2.5+ds-1ubuntu1_amd64 
NAME
ip_allow.yaml - Traffic Server IP access control configuration file
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 address 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. This is a required key.
action The action, which must be allow or deny. This is a required key.
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 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.
NOTE:
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.
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.
As a final example, 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 ] }
]
NOTE:
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.
COPYRIGHT
2025, dev@trafficserver.apache.org
9.2 Mar 17, 2025 IP_ALLOW.YAML(5)