access_controls

ACCESS CONTROLS

Tag Name

acl

Usage

acl aclname acltype string1 ... | "file"

Description
This tag is used for defining an access List. When using "file" the file should contain one item per line By default, regular expressions are CASE-SENSITIVE. To make them case-insensitive, use the -i option.

Acl Type:

src

Description
This will look client IP Address.

Usage

acl aclname src ip-address/netmask.

Example
1.This refers to the whole Network with address 172.16.1.0 - acl aclname src 172.16.1.0/24
2.This refers specific single IP Address - acl aclname src 172.16.1.25/32
3.This refers range of IP Addresses from 172.16.1.25-172.16.1.35 - acl aclname src 172.16.1.25-172.16.1.35/32

Note
While giving Netmask caution must be exerted in what value is given

Acl Type:

dst

Description
This is same as src with only difference refers Server IPaddress. First Squid will dns-lookup for IPAddress from the domain-name, which is in request header. Then this acl is interpreted.

Acl Type:

srcdomain

Description
Since squid needs to reverse dns lookup (from client ip-address to client domain-name) before this acl is interpreted, it can cause processing delays. This lookup adds some delay to the request.

Usage

acl aclname srcdomain domain-name

Example
acl aclname srcdomain .kovaiteam.com

Note
Here "." is more important.

Acl Type:

dstdomain

Description
This is the effective method to control specific domain

Usage

acl aclname dstdomain domain-name

Example
acl aclname dstdomain .kovaiteam.com
Hence this looks for *.kovaiteam.com from URL
Hence this looks for *.kovaiteam.com from URL

Note
Here "." is more important.

Acl Type:

srcdom_regex

Description
Since squid needs to reverse dns lookup (from client ip-address to client domain-name) before this acl is interpreted, it can cause processing delays. This lookup adds some delay to the request

Usage

acl aclname srcdom_regex pattern

Example
acl aclname srcdom_regex kovai
Hence this looks for the word kovai from the client domain name

Note
Better avoid using this acl type to be away from latency.

Acl Type:

dstdom_regex

Description
This is also an effective method as dstdomain

Usage

acl aclname dstdom_regex pattern

Example
acl aclname dstdom_regex kovai
Hence this looks for the word kovai from the client domain name

Acl Type:

time

Description
Time of day, and day of week

Usage

acl aclname time [day-abbreviations] [h1:m1-h2:m2]
day-abbreviations:
S - Sunday
M - Monday
T - Tuesday
W - Wednesday
H - Thursday
F - Friday
A - Saturday
h1:m1 must be less than h2:m2

Example
acl ACLTIME time M 9:00-17:00
ACLTIME refers day of Monday from 9:00 to 17:00.

Acl Type:

url_regex

Description
The url_regex means to search the entire URL for the regular expression you specify. Note that these regular expressions are case-sensitive. To make them case-insensitive, use the -i option.

Usage

acl aclname url_regex pattern

Example
acl ACLREG url_regex cooking
ACLREG refers to the url containing "cooking" not "Cooking"

Acl Type:

urlpath_regex

Description
The urlpath_regex regular expression pattern matching from URL but without protocol and hostname. Note that these regular expressions are case-sensitive

Usage

acl aclname urlpath_regex pattern

Example
acl ACLPATHREG urlpath_regex cooking
ACLPATHREG refers only containing "cooking'' not "Cooking"; and without referring protocol and hostname.
If URL is http://www.visolve.com/folder/subdir/cooking/first.html then this acltype only looks after http://www.visolve.com .
In other words, if URL is http://www.visolve.com/folder/subdir/cooking/first.html then this acltype's regex must match /folder/subdir/cooking/first.html .

Acl Type:

port

Description
Access can be controlled by destination (server) port address

Usage

acl aclname port port-no

Example
This example allows http_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:

proto

Description
This specifies the transfer protocol

Usage

acl aclname proto protocol

Example
acl aclname proto HTTP FTP
This refers protocols HTTP and FTP

Acl Type:

method

Description
This specifies the type of the method of the request

Usage

acl aclname method method-type

Example
acl aclname method GET POST
This refers get and post methods only

Acl Type:

browser

Description
Regular expression pattern matching on the request's user-agent header

Usage

acl aclname browser pattern

Example
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
String matching on the user's name

Usage

acl aclname ident username ...

Example
You can use ident to allow specific users access to your cache. This requires that an ident server process runs on the user's machine(s). In your squid.conf configuration file you would write something like this:

ident_lookup on
acl friends ident kim lisa frank joe
http_access allow friends
http_access deny all

Acl Type:

ident_regex

Description
Regular expression pattern matching on the user's name. String match on ident output. Use REQUIRED to accept any non-null ident

Usage

acl aclname ident_regex pattern

Example
You can use ident to allow specific users access to your cache. This requires that an ident server process run on the user's machine(s). In your squid.conf configuration file you would write something like this:

ident_lookup on
acl friends ident_regex joe
This looks for the pattern "joe" in username

Acl Type:

src_as

Description
source (client) Autonomous System number

Acl Type:

dst_as

Description
destination (server) Autonomous System number

Acl Type:

proxy_auth

Description
User authentication via external processes. proxy_auth requires an EXTERNAL authentication program to check username/password combinations (see authenticate_program ).

Usage

acl aclname proxy_auth username...

use REQUIRED instead of username to accept any valid username

Example
acl ACLAUTH proxy_auth usha venkatesh balu deepa

This acl is for authenticating users usha, venkatesh, balu and deepa by external programs.

Warning
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.

Acl Type:

proxy_auth_regex

Description
This is same as proxy_auth with a difference. That is it matches the pattern with usernames, which are given in authenticate_program

Usage

acl aclname proxy_auth_regex [-i] pattern...


Acl Type:

snmp_community

Description
SNMP community string matching

Example
acl aclname snmp_community public
snmp_access aclname

Acl Type:

snmp_community

Description
A limit on the maximum number of connections from a single client IP address. It is an ACL that will be true if the user has more than maxconn connections open. It is used in http_access to allow/deny the request just like all the other acl types.

Example
acl someuser src 1.2.3.4
acl twoconn maxconn 5
http_access deny someuser twoconn
http_access allow !twoconn

Note
maxconn acl requires client_db feature, so if you disabled that (client_db off) maxconn won't work.

Acl Type:

req_mime_type

Usage

acl aclname req_mime_type pattern

Description
Regular expression pattern matching on the request content-type header

Example
acl aclname req_mime_type text

This acl looks for the pattern "text" in request mime header

Acl Type:

arp

Usage

acl aclname arp ARP-ADDRESS

Description
Ethernet (MAC) address matching This acl is supported on Linux, Solaris, and probably BSD variants.

To use ARP (MAC) access controls, you first need to compile in the optional code.
Do this with the --enable-arp-acl configure option:
% ./configure --enable-arp-acl ...
% make clean
% make

If everything compiles, then you can add some ARP ACL lines to your squid.conf

Default

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 SSL_ports port 443 563
acl Safe_ports port 80 21 443 563 70 210 1025-65535
acl Safe_ports port 280 # http-mgmt
acl Safe_ports port 488 # gss-http
acl Safe_ports port 591 # filemaker
acl Safe_ports port 777 # multiling http
acl CONNECT method CONNECT

Example
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.

Tag Name

http_access

Usage

http_access allow|deny [!]aclname ...

Description
Allowing or denying http access based on defined access lists

If none of the "access" lines cause a match, the default is the opposite of the last line in the list. If the last line was deny, then the default is allow. Conversely, if the last line is allow, the default will be deny. For these reasons, it is a good idea to have a "deny all" or "allow all" entry at the end of your access lists to avoid potential confusion

Default

http_access allow manager localhost
http_access deny manager
http_access deny !Safe_ports
http_access deny CONNECT !SSL_ports
http_access deny all

If there are no "access" lines present, the default is to allow the request

Example
1. To allow http_access for only one machine with MAC Address 00:08:c7:9f:34:41
2. To restrict access to work hours (9am - 5pm, Monday to Friday) from IP 192.168.2/24
3. Can i use multitime access control list for different users for different timing
4. Rules are read from top to bottom

Caution
The deny all line is very important. After all the http_access rules, if access isn't denied, it's ALLOWED !! So, specifying a LOT of http_access allow rules, and forget the deny all after them, is the same of NOTHING. If access isn't allowed by one of your rules, the default action ( ALLOW ) will be triggered. So, don't forget the deny all rule AFTER all the rules.

And, finally, don't forget rules are read from top to bottom. The first rule matched will be used. Other rules won't be applied. Click here to See examples.

Tag Name

icp_access

Usage

icp_access allow|deny [!]aclname ...

Description
icp_access allow|deny [!]aclname ...

Default

icp_access deny all

Example
icp_access allow all - Allow ICP queries from everyone

Tag Name

miss_access

Usage

miss_access allow|deny [!]aclname...

Description
Used to force your neighbors to use you as a sibling instead of a parent. For example:

acl localclients src 172.16.0.0/16
miss_access allow localclients
miss_access deny !localclients

This means that only your local clients are allowed to fetch MISSES and all other clients can only fetch HITS.

Default

By default, allow all clients who passed the http_access rules to fetch MISSES from us.
miss_access allow all


Tag Name

cache_peer_access

Usage

cache_peer_access cache-host allow|deny [!]aclname ...

Description
Similar to 'cache_peer_domain ' but provides more flexibility by using ACL elements.

The syntax is identical to 'http_access' and the other lists of ACL elements. See 'http_access ' for further reference.

Default

none

Example
The following example could be used, if we want all requests from a specific IP address range to go to a specific cache server (for accounting purposes, for example). Here, all the requests from the 10.0.1.* range are passed to proxy.visolve.com, but all other requests are handled directly.

Using acls to select peers,

acl myNet src 10.0.0.0/255.255.255.0
acl cusNet src 10.0.1.0/255.255.255.0
acl all src 0.0.0.0/0.0.0.0
cache_peer proxy.visolve.com parent 3128 3130
cache_peer_access proxy.visolve.com allow custNet
cache_peer_access proxy.visolve.com deny all

Tag Name

proxy_auth_realm

Usage

proxy_auth_realm string

Description
Specifies the realm name, which is to be reported to the client for proxy authentication (part of the text the user will see when prompted for the username and password).

Default

proxy_auth_realm Squid proxy-caching web server

Example
proxy_auth_realm My Caching Server

Tag Name

ident_lookup_access

Usage

ident_lookup_access allow|deny aclname...

Description
A list of ACL elements, which, if matched, cause an ident (RFC 931) lookup to be performed for this request. For example, you might choose to always perform ident lookups for your main multi-user Unix boxes, but not for your Macs and PCs

Default

By default, ident lookups are not performed for any requests
ident_lookup_access deny all

Example
To enable ident lookups for specific client addresses, you can follow this example:

acl ident_aware_hosts src 198.168.1.0/255.255.255.0
ident_lookup_access allow ident_aware_hosts
ident_lookup_access deny all

Caution
This option may be disabled by using --disable-ident with the configure script.

Examples:

(1) To allow http_access for only one machine with MAC Address 00:08:c7:9f:34:41

To use MAC address in ACL rules. Configure with option -enable-arp-acl.

acl all src 0.0.0.0/0.0.0.0
acl pl800_arp arp 00:08:c7:9f:34:41
http_access allow pl800_arp
http_access deny all

(2) To restrict access to work hours (9am - 5pm, Monday to Friday) from IP 192.168.2/24

acl ip_acl src 192.168.2.0/24
acl time_acl time M T W H F 9:00-17:00
http_access allow ip_acl time_acl
http_access deny all

(3) Can i use multitime access control list for different users for different timing.

AclDefnitions

acl abc src 172.161.163.85
acl xyz src 172.161.163.86
acl asd src 172.161.163.87
acl morning time 06:00-11:00
acl lunch time 14:00-14:30
acl evening time 16:25-23:59

Access Controls
http_access allow abc morning
http_access allow xyz morning lunch
http_access allow asd lunch

This is wrong. The description follows:
Here access line "http_access allow xyz morning lunch" will not work. So ACLs are interpreted like this ...

http_access RULE statement1 AND statement2 AND statement3 OR
http_access ACTION statement1 AND statement2 AND statement3 OR

So, the ACL "http_access allow xyz morning lunch" will never work, as pointed, because at any given time, morning AND lunch will ALWAYS be false, because both morning and lunch will NEVER be true at the same time. As one of them is false, and acl uses AND logical statement, 0/1 AND 0 will always be 0 (false).

That's because this line is in two. If now read:

http_access allow xyz AND morning OR
http_access allow xyz lunch

If request comes from xyz, and we're in one of the allowed time, one of the rules will match TRUE. The other will obviously match FALSE. TRUE OR FALSE will be TRUE, and access will be permitted.

Finally Access Control looks...

http_access allow abc morning
http_access allow xyz morning
http_access allow xyz lunch
http_access allow asd lunch
http_access deny all

(4) Rules are read from top to bottom. The first rule matched will be used. Other rules won't be applied.

Example:

http_access allow xyz morning
http_access deny xyz
http_access allow xyz lunch

If xyz tries to access something in the morning, access will be granted. But if he tries to access something at lunchtime, access will be denied. It will be denied by the deny xyz rule, that was matched before the 'xyz lunch' rule.