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Manual:IP/Proxy

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Version.png

Applies to RouterOS: v3, v4

Contents

Summary

Sub-menu: /ip proxy
Standards: RFC 1945, RFC 2616


MikroTik RouterOS performs proxying of HTTP and HTTP-proxy (for FTP, HTTP and HTTPS protocols) requests. Proxy server performs Internet object cache function by storing requested Internet objects, i.e., data available via HTTP and FTP protocols on a system positioned closer to the recipient in the form of speeding up customer browsing by delivering them requested file copies from proxy cache at local network speed. MikroTik RouterOS implements the following proxy server features:

  • Regular HTTP proxy – customer (itself) specify what is proxy server for him
  • Transparent proxy – customer does not know about the proxy being enabled and there isn’t need any additional configuration for web browser of client.
  • Access list by source, destination, URL and requested method (HTTP firewall)
  • Cache access list to specify which objects to cache, and which not.
  • Direct Access List – to specify which resources should be accessed directly, and which - through another proxy server
  • Logging facility – allows to get and to store information about proxy operation
  • Parent proxy support – allows to specify other proxy server, ('if they don’t have the requested object ask their parents, or to the original server.)


A proxy server usually is placed at various points between users and the destination server (also known as origin server) on the Internet. (see Figure 10.1).

Image10001.gif

A Web proxy (cache) watches requests coming from client, saving copies of the responses for itself. Then, if there is another request for the same URL, it can use the response that it has, instead of asking the origin server for it again. If proxy has not requested file, it downloads that from the original server.

There can be many potential purpose of proxy server:

  • To decrease access speed to resources (it takes less time for the client to get the object).
  • Works as HTTP firewall (deny access to undesirable web pages),

Allows to filter web content (by specific parameters, like source address, destination address and port, URL, HTTP request method) scan outbound content, e.g., for data leak protection.

Icon-note.png

Note: it may be useful to have Web proxy running even with no cache when you want to use it only as something like HTTP and FTP firewall (for example, denying access undesired web pages or deny specific type of files e.g. .mp3 files) or to redirect requests to external proxy (possibly, to a proxy with caching functions) transparently.



Proxy configuration example

In MikroTik RouterOS proxy configuration is performed in /ip proxy menu. See below how to enable the proxy on port 8080 and set up 195.10.10.1 as proxy source address:

 [admin@MikroTik] ip proxy> set enabled=yes port=8080 src-address=195.10.10.1

 [admin@MikroTik] ip proxy> print
                      enabled: yes
                  src-address: 195.10.10.1
                         port: 8080
                 parent-proxy: 0.0.0.0:0
                  cache-drive: system
          cache-administrator: "admin@mikrotik.com"
          max-disk-cache-size: none
           max-ram-cache-size: 100000KiB
           cache-only-on-disk: yes
   maximal-client-connections: 1000
   maximal-server-connections: 1000
               max-fresh-time: 3d


When setting up regular proxy service, make sure it serves only your clients and prevent unauthorised access to it by creating firewall that allow only your clients to use proxy, otherwise it may be used as an open proxy.

Remember that regular proxy require also client’s web browser configuration.

For example:

Explorer 8.x

Firefox 3.x

Opera 10.x

Select Tools>Internet options.

Click the Connections tab.

Select the necessary connection and choose Settings button.

Configure proxy address and port.

Select Tools>Options.

Click the Advanced tab.

Open the Network tab.

Click the Connection/Settings

Select Manual proxy configuration'

Select Tool>Preferences.

Open the Advanced tab/Network.

Click the Proxy servers.

Enter proxy address and port.


Transparent proxy configuration example

RouterOS can also act as a Transparent Caching server, with no configuration required in the customer’s web browser. Transparent proxy does not modify requested URL or response. RouterOS will take all HTTP requests and redirect them to the local proxy service. This process will be entirely transparent to the user (users may not know anything about proxy server that is located between them and original server), and the only difference to them will be the increased browsing speed.


To enable the transparent mode, firewall rule in destination NAT has to be added, specifying which connections (to which ports) should be transparently redirected to the proxy. Check proxy settings above and redirect us users (192.168.1.0/24) to proxy server.

[admin@MikroTik] ip firewall nat> add chain=dstnat protocol=tcp src-address=192.168.1.0/24 \
dst-port=80 action=redirect to-ports=8080

 [admin@MikroTik] ip firewall nat> print
 Flags: X - disabled, I - invalid, D - dynamic
  0   chain=dstnat protocol=tcp dst-port=80 action=redirect to-ports=8000
 [admin@MikroTik] ip firewall nat>


The web proxy can be used as transparent and normal web proxy at the same time. In transparent mode it is possible to use it as standard web proxy, too. However, in this case, proxy users may have trouble to reach web pages which are accessed transparently.


Proxy based firewall – Access List

Access list is implemented in the same way as MikroTik firewall rules processed from the top to the bottom. First matching rule specifies decision of what to do with this connection. Connections can be matched by its source address, destination address, destination port, sub-string of requested URL (Uniform Resource Locator) or request method. If none of these parameters is specified, every connection will match this rule.

If connection is matched by a rule, action property of this rule specifies whether connection will be allowed or not (deny). If connection does not match any rule, it will be allowed.

In this example assume that we have configured transparent proxy server as given in example above.

Block particular Websites.

 /ip proxy access add dst-host=www.facebook.com action=deny

It will block website http://www.facebook.com, we can always block the same for different networks by giving src-address.

/ip proxy access add src-address=192.168.1.0/24 dst-host=www.facebook.com action=deny

Users from network 192.168.1.0/24 will not be able to access website www.facebook.com.


You can block also websites that contain specific words in URL:

 /ip proxy access add dst-host=:mail action=deny

This statement will block all websites which contain word “mail” in URL. Like www.mail.com, www.hotmail.com, mail.yahoo.com etc.


We can also stop downloading specific types of files like .flv, .avi, .mp4, .mp3, .exe, .dat, …etc.

 /ip proxy access
 add path=*.flv action=deny
 add path=*.avi action=deny
 add path=*.mp4 action=deny
 add path=*.mp3 action=deny
 add path=*.zip action=deny
 add path=*.rar action=deny.

Here are available also different wildcard characters, to creating specific conditions and to match it by proxy access list.

Wildcard properties (dst-host and dst-path) match a complete string (i.e., they will not match "example.com" if they are set to "example"). Available wildcards are '*' (match any number of any characters) and '?' (match any one character).

Regular expressions are also accepted here, but if the property should be treated as a regular expression, it should start with a colon (':').

To show that no symbols are allowed before the given pattern, we use ^ symbol at the beginning of the pattern.

To specify that no symbols are allowed after the given pattern, we use $ symbol at the end of the pattern.

Reference

List of all available parameters and commands per menu.

General

Sub-menu: /ip proxy


Property Description
always-from-cache (yes | no; Default: no)
cache-administrator (string; Default: webmaster) Administrator's e-mail displayed on proxy error page
cache-hit-dscp (integer: 0..63; Default: 4)
cache-on-disk (yes | no; Default: no)
max-cache-size (none | unlimited | integer: 0..4294967295; Default: none) Specifies the maximal cache size, measured in kibibytes
max-client-connections (integer: 1..5000; Default: 600) Maximal number of connections accepted from clients (any further connections will be rejected)
max-fresh-time (time; Default: 3d) Maximal time to store a cached object. The validity period of an object is is usually defined by the object itself, but in case it is set too high, you can override the maximal value
max-server-connections (integer: 1..5000; Default: 600) Maximal number of connections made to servers (any further connections from clients will be put on hold until some server connections will terminate)
parent-proxy (Ip4 | ip6; Default: 0.0.0.0) IP address and port of another HTTP proxy to redirect all requests to. If set to 0.0.0.0 parent proxy is not used.
parent-proxy-port (integer: 0..65535; Default: 0) Port that parent proxy is listening on.
port (integer: 0..65535; Default: 8080) TCP port the proxy server will be listening on. This port have to be specified on all clients that want to use the server as HTTP proxy. Transparent (with zero configuration for clients) proxy setup can be made by redirecting HTTP requests to this port in IP firewall using destination NAT feature
serialize-connections (yes | no; Default: no)
src-address (Ip4 | Ip6; Default: 0.0.0.0) Proxy will use specified address when connecting to parent proxy or web site. If set to 0.0.0.0 then appropriate IP address will be taken from routing table.

Menu Specific commands

Access List

Sub-menu: /ip proxy access


Access list is configured like a regular firewall rules. Rules are processed from the top to the bottom. First matching rule specifies decision of what to do with this connection. There is a total of 6 classifiers that specify matching constraints. If none of these classifiers is specified, the particular rule will match every connection.

If connection is matched by a rule, action property of this rule specifies whether connection will be allowed or not. If the particular connection does not match any rule, it will be allowed.


Property Description
action (allow | deny; Default: allow) Specifies whether to pass or deny matched packets
dst-address (Ip4[-Ip4 | /0..32] | Ip6/0..128; Default: ) Destination address of the target server.
dst-host (string; Default: ) IP address or DNS name used to make connection the target server (this is the string user wrote in browser before specifying port and path to a particular web page
dst-port (integer[-integer[,integer[,...]]]: 0..65535; Default: ) List or range of ports the packet is destined to
local-port (integer: 0..65535; Default: ) Specifies the port of the web proxy via which the packet was received. This value should match one of the ports web proxy is listening on.
method (any | connect | delete | get | head | options | post | put | trace; Default: ) HTTP method used in the request (see HTTP Methods section in the end of this document)
path (string; Default: ) Name of the requested page within the target server (i.e. the name of a particular web page or document without the name of the server it resides on)
redirect-to (string; Default: ) In case access is denied by this rule, the user shall be redirected to the URL specified here
src-address (Ip4[-Ip4 | /0..32] | Ip6/0..128; Default: ) Source address of the connection originator.


Read only properties:

Property Description
hits (integer) Count of requests that were matched by this rule


Wildcard properties (dst-host and dst-path) match a complete string (i.e., they will not match "example.com" if they are set to "example"). Available wildcards are '*' (match any number of any characters) and '?' (match any one character). Regular expressions are also accepted here, but if the property should be treated as a regular expression, it should start with a colon (':').


Small hints in using regular expressions:

  • \\ symbol sequence is used to enter \ character in console
  • \. pattern means . only (in regular expressions single dot in pattern means any symbol)
  • to show that no symbols are allowed before the given pattern, we use ^ symbol at the beginning of the pattern
  • to specify that no symbols are allowed after the given pattern, we use $ symbol at the end of the pattern
  • to enter [ or ] symbols, you should escape them with backslash \.

It is strongly recommended to deny all IP addresses except those behind the router as the proxy still may be used to access your internal-use-only (intranet) web servers. Also, consult examples in Firewall Manual on how to protect your router.


Direct Access

Sub-menu: /ip proxy direct


If parent-proxy property is specified, it is possible to tell proxy server whether to try to pass the request to the parent proxy or to resolve it connecting to the requested server directly. Direct Access List is managed just like Proxy Access List described in the previous chapter except the action argument.


Unlike the access list, the direct proxy access list has default action equal to deny. It takes place when no rules are specified or a particular request did not match any rule.


Property Description
action (allow | deny; Default: allow) Specifies the action to perform on matched packets:
  • allow - always resolve matched requests directly bypassing the parent router
  • deny - resolve matched requests through the parent proxy. If no one is specified this has the same effect as allow.
dst-address (Ip4[-Ip4 | /0..32] | Ip6/0..128; Default: ) Destination address of the target server.
dst-host (string; Default: ) IP address or DNS name used to make connection the target server (this is the string user wrote in browser before specifying port and path to a particular web page
dst-port (integer[-integer[,integer[,...]]]: 0..65535; Default: ) List or range of ports used by connection to target server.
local-port (integer: 0..65535; Default: ) Specifies the port of the web proxy via which the packet was received. This value should match one of the ports web proxy is listening on.
method (any | connect | delete | get | head | options | post | put | trace; Default: ) HTTP method used in the request (see HTTP Methods section in the end of this document)
path (string; Default: ) Name of the requested page within the target server (i.e. the name of a particular web page or document without the name of the server it resides on)
src-address (Ip4[-Ip4 | /0..32] | Ip6/0..128; Default: ) Source address of the connection originator.


Read only properties:

Property Description
hits (integer) Count of requests that were matched by this rule


Cache Management

Sub-menu: /ip proxy cache


Cache access list specifies, which requests (domains, servers, pages) have to be cached locally by web proxy, and which not. This list is implemented exactly the same way as web proxy access list. Default action is to cache object (if no matching rule is found).


Property Description
action (allow | deny; Default: allow) Specifies the action to perform on matched packets:
  • allow - cache objects from matched request
  • deny - do not cache objects from matched request
dst-address (Ip4[-Ip4 | /0..32] | Ip6/0..128; Default: ) Destination address of the target server
dst-host (string; Default: ) IP address or DNS name used to make connection the target server (this is the string user wrote in browser before specifying port and path to a particular web page
dst-port (integer[-integer[,integer[,...]]]: 0..65535; Default: ) List or range of ports the packet is destined to.
local-port (integer: 0..65535; Default: ) Specifies the port of the web proxy via which the packet was received. This value should match one of the ports web proxy is listening on.
method (any | connect | delete | get | head | options | post | put | trace; Default: ) HTTP method used in the request (see HTTP Methods section in the end of this document)
path (string; Default: ) Name of the requested page within the target server (i.e. the name of a particular web page or document without the name of the server it resides on)
src-address (Ip4[-Ip4 | /0..32] | Ip6/0..128; Default: ) Source address of the connection originator


Read only properties:

Property Description
hits (integer) Count of requests that were matched by this rule


Menu Specific commands

Connections

Sub-menu: /ip proxy connections


This menu conntains the list of current connections the proxy is serving.

Read only properties:

Property Description
client ()
dst-address (Ip4 | Ip6) IPv4/Ipv6 destination address of the connection
protocol (string) Protocol name
rx-bytes (integer) The amount of bytes received by the client
server ()
src-address (Ip4 | Ip6) Ipv4/ipv6 address of the connection originator
state (closing | connecting | converting | hotspot | idle | resolving | rx-header | tx-body | tx-eof | tx-header | waiting) Connection state:
  • closing - the data transfer is finished, and the connection is being finalized
  • connecting - establishing toe connection
  • converting - replacing header and footer fields in response or request paket
  • hotspot - check if hotspot authentication allows to continue (for hotspot proxy)
  • idle - staying idle
  • resolving - resolving server's DNS name
  • rx-header - receiving HTTP header
  • tx-body - transmitting HTTP body to the client
  • tx-eof - writing chunk-end (when converting to chunked response)
  • tx-header - transmitting HTTP header to the client
  • waiting - waiting for transmission form a peer
tx-bytes (integer) The amount of bytes sent by the client


Cache Inserts

Sub-menu: /ip proxy inserts


This menu shows statistics on objects stored in cache (cache inserts).

Read only properties:

Property Description
denied (integer) Number of inserts denied by the caching list.
errors (integer) Number of disk or other system-related errors
no-memory (integer) Number of objects not stored because there was not enough memory
successes (integer) Number of successfull cache inserts.
too-large (integer) Number of objects too large to store

Cache Lookups

Sub-menu: /ip proxy lookup


This menu shows statistics on objects read from cache (cache lookups).

Read only properties:

Property Description
denied (integer) Number of requests denied by the access list.
expired (integer) Number of requests found in cache, but expired, and, thus, requested from an external server
no-expiration-info (integer) Conditional request received for a page that does not have the information to compare the request with
non-cacheable (integer) Number of requests requested from the external servers unconditionally (as their caching is denied by the cache access list)
not-found (integer) Number of requests not found in the cache, and, thus, requested from an external server (or parent proxy if configured accordingly)
successes (integer) Number of requests found in the cache.

Cache Contents

Sub-menu: /ip proxy cache-contents


This menu shows cached contents.

Read only properties:

Property Description
file-size (integer) Cached object size
last-accessed (time)
last-accessed-time (time)
last-modified (time)
last-modified-time (time)
uri (string)


HTTP Methods

Options

This method is a request of information about the communication options available on the chain between the client and the server identified by the Request-URI. The method allows the client to determine the options and (or) the requirements associated with a resource without initiating any resource retrieval


GET

This method retrieves whatever information identified by the Request-URI. If the Request-URI refers to a data processing process than the response to the GET method should contain data produced by the process, not the source code of the process procedure(-s), unless the source is the result of the process.


The GET method can become a conditional GET if the request message includes an If-Modified-Since, If-Unmodified-Since, If-Match, If-None-Match, or If-Range header field. The conditional GET method is used to reduce the network traffic specifying that the transfer of the entity should occur only under circumstances described by conditional header field(-s).


The GET method can become a partial GET if the request message includes a Range header field. The partial GET method intends to reduce unnecessary network usage by requesting only parts of entities without transferring data already held by client.


The response to a GET request is cacheable if and only if it meets the requirements for HTTP caching.


HEAD

This method shares all features of GET method except that the server must not return a message-body in the response. This retrieves the metainformation of the entity implied by the request which leads to a wide usage of it for testing hypertext links for validity, accessibility, and recent modification.


The response to a HEAD request may be cacheable in the way that the information contained in the response may be used to update previously cached entity identified by that Request-URI.


POST

This method requests that the origin server accept the entity enclosed in the request as a new subordinate of the resource identified by the Request-URI.


The actual action performed by the POST method is determined by the origin server and usually is Request-URI dependent.


Responses to POST method are not cacheable, unless the response includes appropriate Cache-Control or Expires header fields.


PUT

This method requests that the enclosed entity be stored under the supplied Request-URI. If another entity exists under specified Request-URI, the enclosed entity should be considered as updated (newer) version of that residing on the origin server. If the Request-URI is not pointing to an existing resource, the origin server should create a resource with that URI.


If the request passes through a cache and the Request-URI identifies one or more currently cached entities, those entries should be treated as stale. Responses to this method are not cacheable.


TRACE

This method invokes a remote, application-layer loop-back of the request message. The final recipient of the request should reflect the message received back to the client as the entity-body of a 200 (OK) response. The final recipient is either the origin server or the first proxy or gateway to receive a Max-Forwards value of 0 in the request. A TRACE request must not include an entity.


Responses to this method MUST NOT be cached.


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