mirror of
https://github.com/mailscope/kumomta.git
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Laurent Marchaud
128 lines
4.3 KiB
Markdown
128 lines
4.3 KiB
Markdown
# Routing Messages Via Proxy Servers
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KumoMTA support SOCK5 and HAProxy for use as forward proxies as part of message delivery.
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The most common use cases for a forward proxy are:
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* Sharing IP addresses between multiple KumoMTA instances for high availability.
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* Leveraging more IP addresses than permitted per instance by a hosting provider.
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* Utilizing IP addresses in remote environments without additional MTA instances.
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Due to the limitations inherent in the HAProxy protocol when used as a forward proxy, it is strongly recommended that SOCKS5 be utilized when possible, but HAProxy support is provided for existing installations migrating to KumoMTA.
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## Using SOCKS5 for Delivery
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### Using The KumoProxy SOCKS5 Proxy Server
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While KumoMTA will work with any compliant SOCKS5 proxy server, we have built KumoProxy to serve as an integrated and supported proxy server specifically for use with KumoMTA.
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Follow the instructions on the [KumoProxy](kumo-proxy.md) page for install and usage.
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### Configuring an egress_source for SOCKS5 Proxy Use
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Configuring an egress_source to use a SOCKS5 proxy server is done as part of
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the [make_egress_source](../../reference/kumo/make_egress_source/index.md) function
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call:
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```lua
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kumo.on('get_egress_source', function(source_name)
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if source_name == 'ip-1' then
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-- Make a source that will emit from 10.0.0.1, via a proxy server
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return kumo.make_egress_source {
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name = 'ip-1',
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-- The SOCKS5 proxy server address and port
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socks5_proxy_server = '10.0.5.10:5000',
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-- Used by the SOCKS5 proxy server to connect to the destination address
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socks5_proxy_source_address = '10.0.0.1',
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ehlo_domain = 'mta1.examplecorp.com',
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}
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end
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end)
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```
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The SOCKS5 proxy server will forward communications via the
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`socks5_proxy_source_address` IP address to reach the remote destination host.
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Each IP address hosted by a SOCKS5 proxy server should be defined as its own
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`egress_source`, IPv4 and IPv6 should be configured as separate sources, but
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can be hosted by the same HAProxy instance(s).
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See the [make_egress_source](../../reference/kumo/make_egress_source/index.md)
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page of the Reference Manual for more information.
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## Using HAProxy for Delivery
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KumoMTA supports V2 of the [HAProxy](https://www.haproxy.org/) [PROXY
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protocol](https://www.haproxy.org/download/2.7/doc/proxy-protocol.txt),
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enabling the use of HAProxy as a forward SMTP proxy for the delivery of
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messages via IP addresses on the HAProxy host.
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### Configuring an egress_source for HAProxy Use
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Configuring an egress_source to use an HAProxy server is done as part of the
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[make_egress_source](../../reference/kumo/make_egress_source/index.md) function call:
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```lua
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kumo.on('get_egress_source', function(source_name)
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if source_name == 'ip-1' then
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-- Make a source that will emit from 10.0.0.1, via a proxy server
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return kumo.make_egress_source {
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name = 'ip-1',
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-- The HAProxy server address and port
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ha_proxy_server = '10.0.5.10:5000',
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-- Used by HAProxy to connect to the destination address
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ha_proxy_source_address = '10.0.0.1',
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ehlo_domain = 'mta1.examplecorp.com',
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}
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end
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end)
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```
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The HAProxy server will forward communications via the
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`ha_proxy_source_address` IP address to reach the remote destination host.
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Each IP address hosted by an HAProxy instance should be defined as its own
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`egress_source`, IPv4 and IPv6 should be configured as separate sources, but
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can be hosted by the same HAProxy instance(s).
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See the [make_egress_source](../../reference/kumo/make_egress_source/index.md)
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page of the Reference Manual for more information.
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### HAProxy Server Configuration
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An example HAProxy server config is as follows:
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```
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global
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log stdout format raw local0 debug
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defaults
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timeout connect 10s
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timeout client 30s
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timeout server 30s
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log global
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listen outboundsmtp
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log global
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bind 0:2526 accept-proxy
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mode tcp
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use-server v4 if { src 0.0.0.0/0 }
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use-server v6 if { src ::/0 }
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server v4 0.0.0.0 source 0.0.0.0 usesrc clientip
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server v6 ::: source ::: usesrc clientip
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```
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The HAProxy instance would be launched with the following command:
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```console
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$ sudo haproxy -f haproxy.conf -V
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```
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For further information on HAProxy, see [the HAProxy Documentation](http://docs.haproxy.org/dev/intro.html).
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