TAG NAME acl

Description Used to define an Access List
Build Option
 Default
Usage
 acl aclname acltype string1 …
acl aclname acltype “file”
Default
 Required minimum configuration for normal functioning


Synopsis
The first field represents the name of the ACL, which is simply an assigned name, that can be just about anything the user chooses. The second field is the type of the ACL, which can be one of a number of choices, that indicates to Squid what part of a request should be matched against for this ACL. The possible types include the requesting clients address, the Web server address or host name, a regular expression matching the URL, and many more. The final field is the actual string to match. Depending on what the ACL type is, this may be an IP address, a series of IP addresses, a URL, a host name, etc.

When using “file”, the file should contain one item per line.

Arguments

aclname
 Name of the acl
acltype
 Type of acl
string
 String to match
file
 File that containing strings
ACL TYPE
 src

Description The IP address of the requesting client, or the clients IP Address
Build Option
 Default
Usage
 acl aclname src ip-address/netmask … (clients IP address)
acl aclname src addr1-addr2/netmask … (range of addresses)
Synopsis
Matching done based on clients ip address

Arguments

aclname
 Access list name
ip-address
 Clients ip address
netmask
 Network mask
add1-addr2
 Range of ip address

Example(s)
acl network1 src 172.16.1.0/24 – refers to the whole Network with address 172.16.1.0
acl source1 src 172.16.1.25/32 – refers to a single source
acl srcrange src 172.16.1.25-172.16.1.35/32 – refers range of IP Addresses from 172.16.1.25-172.16.1.35
ACL TYPE
 dst

Description Same as src but looks for destination IP Address
Build Option
 Default
Usage
 acl aclname dst ip-address/netmask … (URL host’s IP address)
Synopsis
First Squid will dns-lookup for IPAddress from the domain-name, which is in request header. Then this acl is interpreted.

Arguments

aclname
 Access list name
ip-address
 ip-address of the oirgin server/machine
netmask
 Network mask


Example(s)
acl dest dst 63.194.81.67/32
ACL TYPE
 myip

Description The local IP address on which the client connection exists.
Build Option
 Default
Usage
 acl aclname myip ip-address/netmask … (local socket IP address)
Synopsis

Using this acl type, we can specify the local IP address on which the clients connections exists. This allows ACLs to be constructed that only match one physical network, if multiple interfaces are present on the proxy, among other things.


Arguments

aclname
 Access list name
ip-address ip address of the local machine
netmask
 Network mask

Example(s)
acl myip1 myip 172.16.1.53/32
ACL TYPE
 srcdomain

Description This acl type provides matches against the client domain name
Build Option
 Default
Usage
 acl aclname srcdomain .domain-name …
Synopsis
Matching can be either a single domain name, or a list or domain names, or the path to a file that contains a list of domain names. If a path to a file, it must be surrounded by parentheses. This ACL type can increase the latency, and decrease throughput significantly on a loaded cache, as it must perform an address-to-name lookup for each request, so it is usually preferable to use the Client IP Address type.

Note: Here “.” is more important.

Arguments

aclname
 Access list name
domain-name
 Clients domain name

Example(s)
 acl mydomain srcdomain .kovaiteam.com
ACL TYPE
 dstdomain

Description This refers to destination domain i.e. the source domain where the origin server is located
Build Option
 Default
Usage
 acl aclname dstdomain .domain-name …
Synopsis
When matching to be done based on the destination servers domain, you can use this acl type.

Note: Here “.” is more important.

Arguments

aclname
 Access list name
domain-name
 Destination domain

Example(s)
 acl domain1 dstdomain .kovaiteam.com
This looks for *.kovaiteam.com from URL
ACL TYPE
 srcdom_regex

Description Matches against the client domain name
Build Option
 Default
Usage
 acl aclname srcdom_regex [-i] pattern …
Synopsis
Matching can be either a single domain name, or a list of domain names, or a path to a file that contains a list of domain names. If a path to a file ia specified, it must be surrounded parentheses.

Arguments

aclname
 Access list name
pattern
 Pattern to match

Example(s)
 acl aclname srcdom_regex kovai – This looks for the word kovai from the client domain name
ACL TYPE
 dstdom_regex

Description Provides match against destination domain
Build Option
 Default
Usage
 acl aclname dstdom_regex [-i] pattern …
Synopsis
Matching done on destination domain based on regular expression.

Arguments

aclname
 Access list name
pattern
 Patern to match

Example(s)
 acl domain1 dstdom_regex redhat – This looks for the word redhat from the client’s reqest.
ACL TYPE
 time

Description This type is just what it sounds like, providing a means to create ACLs that are active during certain times of the
day or certain days of the week
Build Option
 Default
Usage
 acl aclname time [day-abbrevs] [h1:m1-h2:m2]
Synopsis
Provides timed filter settings. This feature is often used to block some types of content or some sections of the internet during business or class hours. Many companies block pornography, entertainment, sports, and other clearly non-work related sites during business hours, but then unblock them after hours. This might improve workplace efficiency in some situations (or it might just offend the employees). This ACL type allows you to enter days of the week and a time range, or select all hours of the selected days.

Day-abbrevs:
S Sunday
M Monday
T Tuesday
W Wednesday
H Thursday
F Friday
A Saturday
Time:
h1:m1 must be less than h2:m2

Arguments

aclname
 Access list name
day-abbrevs
 Days list (as shown above)
h1:m1-h2:m2
 from and to time

Example(s)
 acl acltime time M 9:00-17:00 – acltime refers day of Monday and time from 9:00 to 17:00.
ACL TYPE
 url_regex

Description Matches using a regular expression on the complete URL
Build Option
 Default
Usage
 acl aclname url_regex [-i] pattern
Synopsis
This ACL can be used to provide access control based on parts of the URL or a case insensitive match of the URL, and much more. The regular expressions used in Squid are provided by the GNU Regex library which is documented in the section 7 and 3 regex manpages. Regular expressions are also discussed briefly in a nice article by Guido Socher at LinuxFocus.

Arguments

aclname
 Access list name
pattern Matching to be done for

Example(s)
acl reject url_regex -i ^http://www.google.co.in/index.html
reject contains the entire url http://www.google.co.in/index.html. If in the http_access if you deny reject, it will deny only the url http://www.google.co.in/index.html but allows the url http://www.google.co.in
ACL TYPE
 urlpath_regex

Description This ACL matches on the URL path minus any protocol, port, and host name information
Build Option
 Default
Usage
 acl aclname urlpath_regex [-i] pattern
Synopsis
This acl type expects for the particular pattern alone from the given URLs. If found the words, it will match it.

Arguments

aclname
 Access list name
pattern
 Pattern which is expected for match

Example(s)
acl reject url_regex -i index.html
reject contains the pattern index.html. If in the http_access if you deny reject, then for any url containing the pattern index.html will be denied.
ACL TYPE
 port

Description This ACL matches on the destination port for the request
Build Option
 Default
Usage
 acl aclname port port-number
acl aclname port range
Synopsis
Matching done on the destination port.

Arguments

aclname
 Access list name
port-number
 Destination port number
range
 Range of port numbers

Example(s)
 The following allows access only to the destination 172.16.1.115:80 from network 172.16.1.0
acl acceleratedhost dst 172.16.1.115/255.255.255.255
acl acceleratedport port 80
acl mynet src 172.16.1.0/255.255.255.0
http_access allow acceleratedhost acceleratedport mynet
http_access deny all
ACL TYPE
 myport

Description This provides match against local socket TCP port
Build Option
 Default
Usage
 acl aclname myport port-numbers …
Synopsis
Matching done on local interface port.

Arguments

aclname
 Access list name
port-numbers
 Local interface port numbers

Example(s)
 acl mp myport 3128
http_access deny 3128
http_access allow all
These will deny all requests coming to the port 3128. Allows requests coming at all other ports.

ACL TYPE
 proto

Description This ACL matches on the protocol of the request
Build Option
 Default
Usage
 acl aclname proto protocol
Synopsis
Matching done based on protocol used in the request such as FTP, HTTP, ICP, etc.

Arguments

aclname
 Access list name
protocol
 Protocol to be matched

Example(s)
acl myproto proto HTTP FTP – This refer protocols HTTP and FTP
ACL TYPE
 method

Description This ACL type matches the HTTP method in the request headers. This includes the methods GET, PUT, etc
Build Option
 Default
Usage
 acl aclname method method-type
Synopsis
Matching done based on the HTTP request method like GET, PUT, etc.

Arguments

aclname
 Access list name
method-type
 HTTP request method

Example(s)
acl getmethod method GET POST – This refers get and post methods only.
ACL TYPE
 browser

Description A regular expression that matches the clients browser type based on the user agent header
Build Option
 Default
Usage
 acl aclname browser [-i] regexp
Synopsis
This allows for ACL’s to operate based on the browser type in use, for example, using this ACL type, one could create an ACL for Netscape users and another for Internet Explorer users.

Arguments

aclname
 Access list name
regexp
 Browser name

Example(s)
 acl aclname browser MOZILLA
This refers to the requests, which are coming from the browsers who have “MOZILLA” keyword in the user-agent header.
ACL TYPE
 ident

Description Provides string matching on user name
Build Option
 Default
Usage
 acl aclname ident username …
Synopsis
Matching based on iden lookups.

Note: Need an external ident server server running on the client machines.

Arguments

aclname
 Access list name
username
 Username to be matched

Example(s)
 You can use ident to allow specific users access to your cache. In your Squid.conf configuration file you would write something like this,
ident_lookup_access allow all
acl friends ident kim lisa frank joe
http_access allow friends
http_access deny all
ACL TYPE
 ident_regex

Description Provides string match on ident output
Build Option
 Default
Usage
 acl aclname ident_regex [-i] pattern
Synopsis
Same as ident but matching is done on ident output.

Note: Need an external ident server server running on the client machines.
Arguments

aclname
 Access list name
pattern
 Pattern to be matched

Example(s)
 In your Squid.conf configuration file you would write something like this,
ident_lookup-access allow all
acl friends ident_regex joe
This looks for the pattern “joe” in username
ACL TYPE
 src_as, dst_as

Description Source Autonomous System Number is another AS related ACL type, and matches on the AS number of thesource of
the request
Destination Autonomous System Number is the AS number of the server being queried
Build Option
 Default
Usage
 acl aclname src_as number
acl aclname dst_as number
Synopsis
The autonomous system number ACL types are generally only used in Cache Peer, or ICP, access restrictions. Autonomous system numbers are used in organizations that have multiple internet links and routers operating under a single administrative authority using the same gateway protocol. Routing decisions are then based on knowledge of the AS in addition to other possible data.

Arguments

aclname
 Access list name
number
 AS numbers to be matched

Example(s)
 An example for routing all requests for AS#1241 and only those to mycache.mydomain.net
acl asexample dst_as 1241
cache_peer_access mycache.mydomain.net allow asexample
cache_peer_access mycache_mydomain.net deny all
ACL TYPE
 proxy_auth

Description This ACL type calls an external authenticator process to decide whether the request will be allowed
Build Option
 Default
Usage
 acl aclname proxy_auth [-i] username …
Synopsis
Some of the authenticator helper programs available for Squid are PAM, NCSA, UNIX passwd, SMB, NTLM, etc. Note that authentication cannot work on a transparent proxy or HTTP accelerator. The HTTP protocol does not provide for two authentication stages (one local and one on remote Web sites). So in order to use an authenticator, your proxy must operate as a traditional proxy, where a client will respond appropriately to a proxy authentication request as well as external Web server authentication requests.

Note: proxy_auth can’t be used in a transparent proxy. It collides with any authentication done by origin servers. It may seem like it works at first, but it doesn’t. When a Proxy-Authentication header is sent but it is not needed during ACL checking the username is NOT logged in access.log.

Arguments

aclname
 Access list name
username
 User name to be authenticated

Example(s)
 acl ACLAUTH proxy_auth ramesh senthil muthu
http_access allow ACLAUTH
http_access deny all
The above configuration will allow only ramesh, senthil and muthu if they give valid username and password.
ACL TYPE
 proxy_auth_regex

Description As above, this ACL calls an external authenticator process, but allows regex pattern or case insensitive matches
Build Option
 Default
Usage
 acl aclname proxy_auth_regex [-i] pattern
Synopsis
Matching based on regular expressions using external authentication process.

Arguments

aclname Access list name
pattern
 Pattern to be matched

Example(s)
acl ACLAUTH proxy_auth_regex -i mesh
ACL TYPE
 snmp_community string …

Description Provides matching against community string to limit access to your SNMP Agent
Build Option
 Default
Usage
 acl aclname snmp_community string …
Synopsis
Matching done on snmp community strings.

Arguments

aclname
 Access list name
string
 String to be matched

Example(s)
 acl snmppublic snmp_community public
ACL TYPE
 maxconn

Description Matches when the client’s IP address has more than the specified number of HTTP connections established
Build Option
 Default
Usage
 acl aclname maxconn number
Synopsis
Matching is true when the defined number of HTTP connections has been established for a client.

Arguments

aclname
 Access list name
number
 Maximum number of HTTP connections

Example(s)
 acl someuser src 1.2.3.4
acl twoconn maxconn 5
http_access deny someuser twoconn
http_access allow !twoconn
The above configuration will allow a maximum of 5 http connection to access.

ACL TYPE
 max_user_ip

Description This will be matched when the same user attempts to log in for more than the specified number of times from
different ip addresses
Build Option
 Default
Usage
 acl aclname max_user_ip [-s] number
Synopsis

If -s is specified then the limit is strict, denying browsing from any further IP addresses until the ttl has expired. Without -s Squid will just annoy the user by “randomly” denying requests. (the counter is then reset each time the limit is reached and a request is denied). The authenticate_ip_ttl parameter controls the timeout on the ip entries.

Note: 1. Any authentication program must be running for this. NCSA will a simple configuration.
2. In acceleration mode or where there is mesh of child proxies, clients may appear to come from multiple addresses if they are going through proxy farms, so a limit of 1 may cause user problems.

Arguments

aclname
 Access list name
number
 Number of times to login

Example(s)
 authenticate_ip_ttl 2 hours
acl maxuser max_user_ip -s 2
http_access deny maxuser
The same user can log to a maximum of 2 times from two different machines and when he tries to login for the third time from a third system, he will not be allowed to browse.

ACL TYPE
 req_mime_type

Description Match against the mime type of the request generated by the client
Build Option
 Default
Usage
 acl aclname req_mime_type mime_type …
Synopsis
Using this you can detect file upload or some types HTTP tunneling requests.

Arguments

aclname
 Access list name
mime_type
 Mime type at the requesting side

Example(s)
 acl mymime req_mime_type text
This acl looks for the pattern “text” in request mime header.

Note
This does NOT match the reply. You cannot use this to match the returned file type.
ACL TYPE
 rep_mime_type

Description Match against the mime type of the reply received by Squid
Build Option
 Default
Usage
 acl aclname rep_mime_type mime_type …
Synopsis
Also, using this, you can detect file download or some types HTTP tunneling requests.

This has no effect in http_access rules. It only has effect in rules that affect the reply data stream such as http_reply_access.

Arguments

aclname
 Access list name
mime_type
 Mime type at the receiving side

Example(s)
 acl m2 rep_mime_type ^application/pdf$
http_reply_access deny m2
This blocks access to application/pdf mime types.
ACL TYPE
 arp

Description Ethernet (MAC) address matching
Build Option
 –enable-arp-acl
Usage
 acl aclname arp mac-address
Synopsis
This option only works for clients on the same local subnet, and only for certain platforms. Linux, Solaris, and some BSD variants are the supported operating systems for this type of ACL. This ACL can provide a somewhat secure method of access control, because MAC addresses are usually harder to spoof than IP addresses, and you can guarantee that your clients are on the local network (otherwise no ARP resolution can take place).

Arguments

aclname
 Access list name
mac-address
 Physical address to be matched

Example(s)
 acl ACLARP arp 11:12:13:14:15:16
ACLARP refers MACADDRESS of the ethernet 11:12:13:14:15:16

Note
Squid can only determine the MAC address for clients that are on the same subnet. If the client is on a different subnet, then Squid cannot find out its MAC address.
ACL TYPE
 external

Description Provides match against external ACL lookup via a helper class defined by the external_acl_type tag
Build Option
 Default
Usage
 acl aclname external class_name [arguments...]
Synopsis
Provides match against external ACL lookup via a helper class defined by the external_acl_type tag

Arguments

aclname
 Access list name
class_name
 Defined by external_acl_type tag

Example(s)

auth_param basic program < put your authenticator here >
auth_param basic children 20
auth_param basic realm Squid proxy-caching web server
auth_param basic credentialsttl 1800 seconds
external_acl_type checkip children=20 %LOGIN %SRC /usr/local/Squid/bin/checkip.pl
acl password external checkip
acl it src 172.16.20.1-172.16.20.199/255.255.255.255
http_access allow it password

Allows user if user belongs to a group that is allowed during a given time and using a given ip.

Recommended minimum acl configuration
acl all src 0.0.0.0/0.0.0.0
acl manager proto cache_object
acl localhost src 127.0.0.1/255.255.255.255
acl to_localhost dst 127.0.0.0/8
acl SSL_ports port 443 563
acl Safe_ports port 80
acl Safe_ports port 21
acl Safe_ports port 443 563
acl Safe_ports port 70
acl Safe_ports port 210
acl Safe_ports port 1025-65535
acl Safe_ports port 280
acl Safe_ports port 488
acl Safe_ports port 591
acl Safe_ports port 777
acl CONNECT method CONNECT