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SME Server:Documentation:Administration Manual:Appendix (view source)

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===SME Manual Appendix===
 
===SME Manual Appendix===
 
The following Appendix pages are included for your information.
 
The following Appendix pages are included for your information.
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A local area network (LAN) is the system of wires and other hardware that connects the computers within your office and allows them to communicate with one another. An ethernet LAN is the most common type. Ethernet refers both to a kind of connection and to a protocol for how Internet data packets travel around your network.
 
A local area network (LAN) is the system of wires and other hardware that connects the computers within your office and allows them to communicate with one another. An ethernet LAN is the most common type. Ethernet refers both to a kind of connection and to a protocol for how Internet data packets travel around your network.
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The hub, a common component of an ethernet, serves as a point of interface between computers on the network. Each computer on your network is connected to the hub using an ethernet network cable. Different hubs operate at different speeds: slower hubs, operating at 10 MB/sec, are suitable for small networks; faster hubs, operating at 100 MB/sec, are suitable for larger networks. Switching 10/100 MB hubs can operate at either speed, and provide a good way to upgrade your network gradually.
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The hub, a common component of an ethernet, serves as a point of interface between computers on the network. Each computer on your network is connected to the hub using an ethernet network cable. Different hubs operate at different speeds: slower hubs, operating at 100 Mb/sec, are suitable for small networks; faster hubs, operating at 1 Gb/sec, are suitable for larger networks. Switching 100Mb/1 Gb hubs can operate at either speed, and provide a good way to upgrade your network gradually.
    
An ethernet adapter, also called an ethernet card or network interface card (NIC), connects each computer to the ethernet LAN. An server with a dedicated Internet connection requires two ethernet adapters; one connects it to your LAN and the other connects it to the external network that leads to your ISP. If your server connects to your ISP using a modem or ISDN adapter, it only requires one ethernet adapter.
 
An ethernet adapter, also called an ethernet card or network interface card (NIC), connects each computer to the ethernet LAN. An server with a dedicated Internet connection requires two ethernet adapters; one connects it to your LAN and the other connects it to the external network that leads to your ISP. If your server connects to your ISP using a modem or ISDN adapter, it only requires one ethernet adapter.
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Allowing a third party, such as a systems integrator or networking company, to install your ethernet can be a good idea. It can help you select, procure and install the appropriate ethernet adapters, hub and cables. There are also various how-to guides available in bookstores if you are committed to installing it on your own.
 
Allowing a third party, such as a systems integrator or networking company, to install your ethernet can be a good idea. It can help you select, procure and install the appropriate ethernet adapters, hub and cables. There are also various how-to guides available in bookstores if you are committed to installing it on your own.
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====Appendix B. Dynamic DNS Services====
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<!--
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The original title of this article was 'Appendix B. Dynamic DNS Services'
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The following pages link to that address:
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http://wiki.contribs.org/SME_Server:Documentation:Administration_Manual:Chapter3
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http://wiki.contribs.org/SME_Server:Documentation:Administration_Manual:Chapter5
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http://wiki.contribs.org/SME_Server:Documentation:Administration_Manual:Booklet
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http://wiki.contribs.org/SME_Server:Documentation:Administration_Manual:Chapter3/de
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http://wiki.contribs.org/SME_Server:Documentation:Administration_Manual:Appendix/de
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-->====Appendix B. DNS====
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DNS or the Domain Name Service is a distributed system of servers designed to translate human-readable names into computer routable IP addresses.
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=====DNS Basics=====
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SME, by design, does not respond to DNS queries from outside your local network, and ''cannot'' be used as a public DNS server for anyone outside your location. 
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If you want your SME server to be available to users outside your office using a ''name'' instead of your IP address, you MUST:
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* Register your domain name with a Registrar
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* Configure your host names on a publicly accessible DNS Server
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Note: you can avoid 'Registering' your domain name if you use [[#Dynamic DNS Services]]
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Imagine the following scenario:
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Root_DNS
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  |    Registrar
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  |    /  DNS Server
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  |  /  /            Other_DNS
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  |  |  /            /
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  Internet---Other_ISP---Remote_User
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      |
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  Your_ISP---Your_ISPs_DNS
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      |
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    SME
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      |
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  Local_User
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Let's assume that
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* SME has IP Address a.b.c.d
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* SME has domain name mysmeserver.com
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* '''Remote_User''' is configured to use '''Other_DNS''' for DNS lookups
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If Remote_User tries to browse to http://mysmeserver.com, his computer asks '''Other_DNS''' how to find 'mysmeserver.com'.  '''Other_DNS''' server then
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* asks the '''Root_DNS''' servers for the '''Registrar''' in charge of 'mysmeserver.com'
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* asks the '''Registrar''' for the '''DNS_Server''' that will answer queries about 'mysmeserver.com'
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* asks the '''DNS_Server''' for the IP address of 'mysmeserver.com'
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* saves the answer in its local cache for the amount of time specified by the administrator of the DNS record at '''DNS_Server'''.
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If, on the other hand, '''Remote_User''' asks for information about your IP address (a.b.c.d), his DNS server
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* asks the '''Root_DNS''' servers where d.c.b.a.in-addr.arpa is registered.
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* asks the '''Registrar''' where to get more info about d.c.b.a.in-addr.arpa.  This is probably but not necessarily '''Your_ISPs_DNS'''.
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* asks the host indicated by the '''Registrar''' (probably '''Your_ISPs_DNS''') what name belongs to 'd.c.b.a.in-addr.arpa'.  The return value is almost always a generic filler based on your IP address unless you contact your ISP and ask them to change the PTR data for your IP address.
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Basically, PTR records are managed by the organization that controls the IP address (which makes sense, if you think about it).
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If Local_User tries to open http://mysmeserver.com (assuming a default SME installation with DHCP and therefore DNS provided by the SME server):
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* If mysmeserver.com is configured for Local resolution, the SME server returns the data that has been configured locally.
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* If mysmeserver.com is configured to use Internet DNS Servers, the SME proceeds just as the first example from Root_DNS to Registrar to DNS_Server to local cache (actually, it checks the local cache first...)
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So, for you to host a public web server at your own location you need:
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* An ISP to provide connectivity
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* A DNS Registrar where you can 'register' your domain name and publish the addresses of your DNS servers.
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* A DNS service provider who will respond to queries about your domain
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Some ISP's provide registration and DNS hosting capabilities as part of the connectivity package.
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Some ISP's provide DNS hosting but not Registration as part of the connectivity package.
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Some Registrars provide DNS hosting as part of the registration.
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Sometimes you will need 3 separate vendors for these separate services.
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If you have already registered your domain name, find out if your Registrar provides DNS hosting services, and if so, how to configure them.  They'll provide you with a web address where you can configure your DNS.
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If they do NOT provide DNS hosting services, your ISP might.  Ask them.  If so, configure your DNS on their servers, then edit the Registrar page to point to the DNS servers indicated by your ISP.
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If neither your Registrar nor your ISP provides DNS hosting, you'll need to find a 3rd party vendor to do this.  See [[#DNS_Service_Providers]] below.
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If you have not yet registered your domain name, try to find a Registrar who provides free DNS services.
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=====PTR Records=====
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PTR Records (or Pointer records, or Reverse DNS records) are used by internet hosts to convert an IP address into a name - sometimes for information only, sometimes for identity verification.
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PTR records are constructed by ''reversing'' your IP address and appending the special suffix 'in-addr.arpa'.  For example, the PTR record for ''a.b.c.d'' is ''d.c.b.a.in-addr.arpa''.
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A DNS lookup for a PTR record looks just like a DNS lookup for a domain name at this point - Root_DNS, Registrar, DNS_Server, except that the return value will be a host name instead of an IP address.
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With very few exceptions all PTR records are registered to the ISP that controls the IP block in question, so frequently the ONLY way to change your PTR records is to contact your ISP and request that they be changed.
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PTR records are only rarely used for their original purpose of verifying the identity of a particular computer - this is now done with SSL certificates and Trust Authorities.
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The PTR record for your SME Server only becomes important if you plan to deliver email directly from your SME to recipient email servers (without using your ISP's mail server as a relay).  Some email providers will not accept your email if the name returned by the 'reverse lookup' of your IP address does not in its turn result in your IP address when it, itself is looked up.  It doesn't necessarily need to match your configured domain name, but it has to work both ways. 
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For example, if the ''nslookup d.c.b.a.in-addr.arpa'' (the reverse lookup for your IP) returns ''dsl-a-b-c-d.mycity.myispsname.com'' then before trying to send email directly from your SME to the Internet at large you want to make sure that ''nslookup dsl-a-b-c-d.mycity.myispsname.com'' returns your ''a.b.c.d'' and not an error or some other address.
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=====SPF Records=====
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SPF (Sender Policy Framework) records are added to the DNS zone record for domain names. Many receiving mail servers now require sending mail servers to have properly configured SPF records for the domain(s) being sent from. Failure to have SPF records can result in mail being rejected by mail servers eg Hotmail servers will reject mail that comes from mail servers without SPF records.
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The SPF entries are added to your external DNS records which are hosted by your connectivity ISP. They are not configured on the sme server.
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See [http://www.open-spf.org/ here].
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Here is a [https://mxtoolbox.com/spf.aspx test site] where you can check if SPF records are configured for your domain.
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Different providers have different mail acceptance policies.
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Look for tech support pages for the provider.
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References:
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http://forums.contribs.org/index.php/topic,21631.0.html
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http://forums.contribs.org/index.php/topic,31726.0.html
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http://forums.contribs.org/index.php/topic,34664.0.html
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http://forums.contribs.org/index.php/topic,40009.0.html
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http://forums.contribs.org/index.php/topic,42373.0.html
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=====Dynamic DNS Services=====  
 
If your IP address is assigned dynamically, you may find it helpful to use a dynamic DNS service. A dynamic DNS service provides you with an automated way to notify them whenever your IP address changes so that they can immediately publish new DNS records for your domain. Without dynamic DNS, you would have to contact your ISP to have them change your DNS records, and your web site and other services would be unavailable for several days until the change was processed. You can easily enable the usage of a dynamic DNS service by selecting it on your server console.
 
If your IP address is assigned dynamically, you may find it helpful to use a dynamic DNS service. A dynamic DNS service provides you with an automated way to notify them whenever your IP address changes so that they can immediately publish new DNS records for your domain. Without dynamic DNS, you would have to contact your ISP to have them change your DNS records, and your web site and other services would be unavailable for several days until the change was processed. You can easily enable the usage of a dynamic DNS service by selecting it on your server console.
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A dynamic DNS service can be a great solution when used with a dedicated connection. With a typical dialup connection, your IP address changes much more frequently (possibly every time your server connects) and, because the server only connects intermittently, there is a delay in informing the dynamic DNS service of the change. This means that the risk of misdirected information is much greater with a dialup connection. For this reason, we recommend and support the use of dynamic DNS services only for dedicated connections.
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{{warning box|Pre-configured Dynamic DNS Service is no longer integrated into SME Server core functionality due to its rapidly changing providers. If you need this service, please refer to the "smeserver-dyndns" contrib.}}
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<!--Contribs.org has tested four dynamic DNS services, of which two are free services and two are commercial services: yi.org (free), dyndns.com (commercial), tzo.com (commercial) and dyndns.org (free). For simplicity, we have preprogrammed the server to work with these services (including pre-installing their client software). If you have arranged dynamic IP address assignment from your ISP and you wish to use one of these services, all you need to do is visit the appropriate web site to sign up for service, and enable that particular function in the server console. In pre-configuring the server for this particular service, we in no way interfere with nor prevent you from using another dynamic DNS service if you wish. To do so, however, would require some customized configuration on your part.
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Contribs.org has tested the functionality of these services with our software. However, we accept no liability for any breach of service on their part. A failure on the part of your dynamic DNS service can result in your network becoming temporarily unreachable from the Internet. During these times, your e-mail may be undeliverable.-->
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If your IP address is assigned dynamically and you intend to receive all your e-mail directly (rather than having it stored at an ISP and retrieving it via POP or IMAP), but you decide not to use a dynamic DNS service, you should implement multidrop e-mail as your e-mail solution as this will ensure that no e-mail is misdirected to another IP address (See Some important notes on Service list D (multidrop mail) in|[[SME_Server:Documentation:Administration_Manual:Chapter3#Service_List_D | Chapter 3]].)
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Contribs.org has tested four dynamic DNS services, of which two are free services and two are commercial services: yi.org (free), dyndns.com (commercial), tzo.com (commercial) and dyndns.org (free). For simplicity, we have preprogrammed the server to work with these services (including pre-installing their client software). If you have arranged dynamic IP address assignment from your ISP and you wish to use one of these services, all you need to do is visit the appropriate web site to sign up for service, and enable that particular function in the server console. In pre-configuring the server for this particular service, we in no way interfere with nor prevent you from using another dynamic DNS service if you wish. To do so, however, would require some customized configuration on your part.
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{{Note box|Dynamic DNS services are not perfect. They merely point hostnames to IP addresses. If your system receives an IP address via DHCP or PPPoE, it will automatically update the dynamic DNS service each time it comes online. However, when your server disconnects from the Internet, with most dynamic DNS services your server does not indicate that it is offline in any way to the dynamic DNS service. If your system is offline for a period of time, it is possible that someone else will be assigned your IP address by your ISP. If this occurs, with most dynamic DNS services this other system will now start receiving your e-mail and web page requests until your server comes back online and updates the service with your new IP address. There is not much you can do about this, but you should be aware of this fact if there is any chance your system will be offline for a long period of time.}}
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Contribs.org has tested the functionality of these services with our software. However, we accept no liability for any breach of service on their part. A failure on the part of your dynamic DNS service can result in your network becoming temporarily unreachable from the Internet. During these times, your e-mail may be undeliverable.
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{{Note box|If you are using an IP address whether dynamically allocated or fixed, but located within a DSL block assigned to a provider of home connectivity services it may very well be blocked by mainline ISPs, so that you are not able to send email from it. The solution is to use a '''smarthost''' to relay your email, this being provided by your connectivity provider, check their documentation. The smarthost settings can be configured in the Server Manager email settings. This issue as noted applies to both fixed and dynamic IP addresses.}}
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If your IP address is assigned dynamically and you intend to receive all your e-mail directly (rather than having it stored at an ISP and retrieving it via POP or IMAP), but you decide not to use a dynamic DNS service, you should implement multidrop e-mail as your e-mail solution as this will ensure that no e-mail is misdirected to another IP address (See Some important notes on Service list D (multidrop mail) in|Chapter 3.)
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=====DNS Service Providers=====
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Here is a brief list of vendors who provide DNS service hosting.  The inclusion of a vendor here does not constitute endorsement by the SME developers.
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{{DrawBoxNote|content=Dynamic DNS services are not perfect. They merely point hostnames to IP addresses. If your system receives an IP address via DHCP or PPPoE, it will automatically update the dynamic DNS service each time it comes online. However, when your server disconnects from the Internet, with most dynamic DNS services your server does not indicate that it is offline in any way to the dynamic DNS service. If your system is offline for a period of time, it is possible that someone else will be assigned your IP address by your ISP. If this occurs, with most dynamic DNS services this other system will now start receiving your e-mail and web page requests until your server comes back online and updates the service with your new IP address. There is not much you can do about this, but you should be aware of this fact if there is any chance your system will be offline for a long period of time.}}
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*Dyndns.com  http://www.dyndns.com      $$$ (for 'Custom DNS' services)
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*DuckDNS      https://www.duckdns.org/    $free
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*Zoneedit    http://www.zoneedit.com    $free
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*FreeDNS      http://freedns.afraid.org  $free
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*EasyDNS      http://www.easydns.com      $19.95USD per year
    
====Appendix C. Proxy Servers====
 
====Appendix C. Proxy Servers====
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If you are having difficulty configuring another vendor's hardware or software, we recommend you refer to the manual or contact the vendor for that product.
 
If you are having difficulty configuring another vendor's hardware or software, we recommend you refer to the manual or contact the vendor for that product.
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The SME Server is open source software, Contribs.org encourages users to freely share copies of our software.
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The SME Server is open source software, Koozali.org encourages users to freely share copies of our software.
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Developers may wish to note that additional documentation, including HOWTO documents and a FAQ, can be found on our development web site - http://wiki.contribs.org/. There are also links there to other web sites relating to the server.
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Developers may wish to note that additional documentation, including HOWTO documents and a FAQ, can be found on our development web site - http://wiki.koozali.org/. There are also links there to other web sites relating to the server.
Retrieved from "https://wiki.koozali.org/Special:MobileDiff/3135...40190"

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