Webproxy

The proxy service in VyOS is based on Squid and some related modules.

Squid is a caching and forwarding HTTP web proxy. It has a wide variety of uses, including speeding up a web server by caching repeated requests, caching web, DNS and other computer network lookups for a group of people sharing network resources, and aiding security by filtering traffic. Although primarily used for HTTP and FTP, Squid includes limited support for several other protocols including Internet Gopher, SSL,[6] TLS and HTTPS. Squid does not support the SOCKS protocol.

URL Filtering is provided by SquidGuard.

Configuration

set service webproxy append-domain <domain>

Use this command to specify a domain name to be appended to domain-names within URLs that do not include a dot . the domain is appended.

Example: to be appended is set to vyos.net and the URL received is www/foo.html, the system will use the generated, final URL of www.vyos.net/foo.html.

set service webproxy append-domain vyos.net
set service webproxy cache-size <size>

The size of the on-disk Proxy cache is user configurable. The Proxies default cache-size is configured to 100 MB.

Unit of this command is MB.

set service webproxy cache-size 1024
set service webproxy default-port <port>

Specify the port used on which the proxy service is listening for requests. This port is the default port used for the specified listen-address.

Default port is 3128.

set service webproxy default-port 8080
set service webproxy domain-block <domain>

Used to block specific domains by the Proxy. Specifying “vyos.net” will block all access to vyos.net, and specifying “.xxx” will block all access to URLs having an URL ending on .xxx.

set service webproxy domain-block vyos.net
set service webproxy domain-noncache <domain>

Allow access to sites in a domain without retrieving them from the Proxy cache. Specifying “vyos.net” will allow access to vyos.net but the pages accessed will not be cached. It useful for working around problems with “If-Modified-Since” checking at certain sites.

set service webproxy domain-noncache vyos.net
set service webproxy listen-address <address>

Specifies proxy service listening address. The listen address is the IP address on which the web proxy service listens for client requests.

For security, the listen address should only be used on internal/trusted networks!

set service webproxy listen-address 192.0.2.1
set service webproxy listen-address <address> disable-transparent

Disables web proxy transparent mode at a listening address.

In transparent proxy mode, all traffic arriving on port 80 and destined for the Internet is automatically forwarded through the proxy. This allows immediate proxy forwarding without configuring client browsers.

Non-transparent proxying requires that the client browsers be configured with the proxy settings before requests are redirected. The advantage of this is that the client web browser can detect that a proxy is in use and can behave accordingly. In addition, web-transmitted malware can sometimes be blocked by a non-transparent web proxy, since they are not aware of the proxy settings.

set service webproxy listen-address 192.0.2.1 disable-transparent
set service webproxy listen-address <address> port <port>

Sets the listening port for a listening address. This overrides the default port of 3128 on the specific listen address.

set service webproxy listen-address 192.0.2.1 port 8080
set service webproxy reply-block-mime <mime>

Used to block a specific mime-type.

# block all PDFs
set service webproxy reply-block-mime application/pdf
set service webproxy reply-body-max-size <size>

Specifies the maximum size of a reply body in KB, used to limit the reply size.

All reply sizes are accepted by default.

set service webproxy reply-body-max-size 2048

Authentication

The embedded Squid proxy can use LDAP to authenticate users against a company wide directory. The following configuration is an example of how to use Active Directory as authentication backend. Queries are done via LDAP.

set service webproxy authentication children <number>

Maximum number of authenticator processes to spawn. If you start too few Squid will have to wait for them to process a backlog of credential verifications, slowing it down. When password verifications are done via a (slow) network you are likely to need lots of authenticator processes.

This defaults to 5.

set service webproxy authentication children 10
set service webproxy authentication credentials-ttl <time>

Specifies how long squid assumes an externally validated username:password pair is valid for - in other words how often the helper program is called for that user. Set this low to force revalidation with short lived passwords.

Time is in minutes and defaults to 60.

set service webproxy authentication credentials-ttl 120
set service webproxy authentication method <ldap>

Proxy authentication method, currently only LDAP is supported.

set service webproxy authentication method ldap
set service webproxy authentication realm

Specifies the protection scope (aka realm name) which is to be reported to the client for the authentication scheme. It is commonly part of the text the user will see when prompted for their username and password.

set service webproxy authentication realm "VyOS proxy auth"

LDAP

set service webproxy authentication ldap base-dn <base-dn>

Specifies the base DN under which the users are located.

set service webproxy authentication ldap base-dn DC=vyos,DC=net
set service webproxy authentication ldap bind-dn <bind-dn>

The DN and password to bind as while performing searches.

set service webproxy authentication ldap bind-dn CN=proxyuser,CN=Users,DC=vyos,DC=net
set service webproxy authentication ldap filter-expression <expr>

LDAP search filter to locate the user DN. Required if the users are in a hierarchy below the base DN, or if the login name is not what builds the user specific part of the users DN.

The search filter can contain up to 15 occurrences of %s which will be replaced by the username, as in “uid=%s” for RFC 2037 directories. For a detailed description of LDAP search filter syntax see RFC 2254.

set service webproxy authentication ldap filter-expression (cn=%s)
set service webproxy authentication ldap password <password>

The DN and password to bind as while performing searches. As the password needs to be printed in plain text in your Squid configuration it is strongly recommended to use a account with minimal associated privileges. This to limit the damage in case someone could get hold of a copy of your Squid configuration file.

set service webproxy authentication ldap password vyos
set service webproxy authentication ldap persistent-connection

Use a persistent LDAP connection. Normally the LDAP connection is only open while validating a username to preserve resources at the LDAP server. This option causes the LDAP connection to be kept open, allowing it to be reused for further user validations.

Recommended for larger installations.

set service webproxy authentication ldap persistent-connection
set service webproxy authentication ldap port <port>

Specify an alternate TCP port where the ldap server is listening if other than the default LDAP port 389.

set service webproxy authentication ldap port 389
set service webproxy authentication ldap server <server>

Specify the LDAP server to connect to.

set service webproxy authentication ldap server ldap.vyos.net
set service webproxy authentication ldap use-ssl

Use TLS encryption.

set service webproxy authentication ldap use-ssl
set service webproxy authentication ldap username-attribute <attr>

Specifies the name of the DN attribute that contains the username/login. Combined with the base DN to construct the users DN when no search filter is specified (filter-expression).

Defaults to ‘uid’

Note

This can only be done if all your users are located directly under the same position in the LDAP tree and the login name is used for naming each user object. If your LDAP tree does not match these criterias or if you want to filter who are valid users then you need to use a search filter to search for your users DN (filter-expression).

set service webproxy authentication ldap username-attribute uid
set service webproxy authentication ldap version <2 | 3>

LDAP protocol version. Defaults to 3 if not specified.

set service webproxy authentication ldap version 2

URL filtering

Call for Contributions

This section needs improvements, examples and explanations.

Please take a look at the Contributing Guide for our Write Documentation.

set service webproxy url-filtering disable

Disables web filtering without discarding configuration.

set service webproxy url-filtering disable

Operation

Call for Contributions

This section needs improvements, examples and explanations.

Please take a look at the Contributing Guide for our Write Documentation.

Filtering

Update

If you want to use existing blacklists you have to create/download a database first. Otherwise you will not be able to commit the config changes.

update webproxy blacklists

Download/Update complete blacklist

vyos@vyos:~$ update webproxy blacklists
Warning: No url-filtering blacklist installed
Would you like to download a default blacklist? [confirm][y]
Connecting to ftp.univ-tlse1.fr (193.49.48.249:21)
blacklists.gz        100% |*************************************************************************************************************| 17.0M  0:00:00 ETA
Uncompressing blacklist...
Checking permissions...
Skip link for   [ads] -> [publicite]
Building DB for [adult/domains] - 2467177 entries
Building DB for [adult/urls] - 67798 entries
Skip link for   [aggressive] -> [agressif]
Building DB for [agressif/domains] - 348 entries
Building DB for [agressif/urls] - 36 entries
Building DB for [arjel/domains] - 69 entries
...

Building DB for [webmail/domains] - 374 entries
Building DB for [webmail/urls] - 9 entries

The webproxy daemon must be restarted
Would you like to restart it now? [confirm][y]

[ ok ] Restarting squid (via systemctl): squid.service.
vyos@vyos:~$
update webproxy blacklists category <category>

Download/Update partial blacklist.

Use tab completion to get a list of categories.

  • To auto update the blacklist files

    set service webproxy url-filtering squidguard auto-update update-hour 23

  • To configure blocking add the following to the configuration

    set service webproxy url-filtering squidguard block-category ads

    set service webproxy url-filtering squidguard block-category malware

Bypassing the webproxy

Call for Contributions

This section needs improvements, examples and explanations.

Please take a look at the Contributing Guide for our Write Documentation.

Some services don’t work correctly when being handled via a web proxy. So sometimes it is useful to bypass a transparent proxy:

  • To bypass the proxy for every request that is directed to a specific destination:

    set service webproxy whitelist destination-address 198.51.100.33

    set service webproxy whitelist destination-address 192.0.2.0/24

  • To bypass the proxy for every request that is coming from a specific source:

    set service webproxy whitelist source-address 192.168.1.2

    set service webproxy whitelist source-address 192.168.2.0/24

    (This can be useful when a called service has many and/or often changing destination addresses - e.g. Netflix.)

Examples

vyos@vyos# show service webproxy
 authentication {
     children 5
     credentials-ttl 60
     ldap {
         base-dn DC=example,DC=local
         bind-dn CN=proxyuser,CN=Users,DC=example,DC=local
         filter-expression (cn=%s)
         password Qwert1234
         server ldap.example.local
         username-attribute cn
     }
     method ldap
     realm "VyOS Webproxy"
 }
 cache-size 100
 default-port 3128
 listen-address 192.168.188.103 {
     disable-transparent
 }