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how_to:vpop3_access_security

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how_to:vpop3_access_security [2011/09/14 09:40] – [VPOP3 version 2.5 to 4.0] paulhow_to:vpop3_access_security [2011/09/14 09:53] – [VPOP3 version 2.5 to 4.0] paul
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 To edit a rule, you can click on the rule, to add a rule, click on the **Add New Rule** text, or to remove a rule click on the **X** or waste bin to the left of the rule. To edit a rule, you can click on the rule, to add a rule, click on the **Add New Rule** text, or to remove a rule click on the **X** or waste bin to the left of the rule.
  
-When adding or editing a rule you can specify whether the rule applies to a single host, a subnet (specified in [[http://en.wikipedia.org/wiki/CIDR_notation|CIDR format]], as <network address>/<mask>, eg 192.168.0.0/24) or all addresses. You can also specify whether the restriction block access (DENY) or allows access (ALLOW). +When adding or editing a rule you can specify whether the rule applies to a single host, a subnet (specified in [[http://en.wikipedia.org/wiki/CIDR_notation|CIDR format]], as <network address>/<mask>, eg 192.168.0.0/24) or all addresses. You can also specify whether the restriction blocks access (DENY) or allows access (ALLOW). 
  
 If the service requires authentication, then you can also specify which users can access it from these addresses (if you don't specify any users, then all users are allowed). Note that with SMTP, if the service is configured never to require authentication, then you cannot restrict by username, as VPOP3 can not know a username, unless authentication is used. If the service requires authentication, then you can also specify which users can access it from these addresses (if you don't specify any users, then all users are allowed). Note that with SMTP, if the service is configured never to require authentication, then you cannot restrict by username, as VPOP3 can not know a username, unless authentication is used.
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 If the service allows (but does not require) authentication (eg SMTP, LDAP), then there will also be a **no auth** checkbox which allows you to say that, from the specified IP addresses, authentication is not required, even if the settings normally require authentication. If the service allows (but does not require) authentication (eg SMTP, LDAP), then there will also be a **no auth** checkbox which allows you to say that, from the specified IP addresses, authentication is not required, even if the settings normally require authentication.
  
 +====Default for your LAN====
 +The **Default for your LAN** button makes VPOP3 create a default set of rules which are likely to be OK for basic internal LAN usage scenarios
 +
 +What it does is:
 +  - create a **DENY** rule for any gateways (routers)
 +  - create an **ALLOW** rule for each network which the VPOP3 computer is directly connected to
 +
 +For more situations, this will create a set of rules such as:
 +  * DENY 192.168.1.1   (the router address)
 +  * ALLOW 192.168.1.0/24 (the local network)
 +  * ALLOW 127.0.0.0/8 (the loopback addresses)
 +
 +If there are multiple network adapters (or multiple IP addresses bound to a single adapter), then there may be more entries.
 +
 +The **Default for your LAN** button cannot automatically detect if you have multiple local networks connected by internal routers, but if you have that level of complexity of network topography, it should be relatively clear how you need to configure the access restrictions to do what you require.
 +
 +
 +(Note that VPOP3 detects the LAN configuration when starting up, so if the IP address/network details are changed since VPOP3 started, it will configure the settings incorrectly using this button. This can especially be an issue if VPOP3 is connected via a wireless LAN.)
 +
 +===The default DENY rule for your router/gateway===
 +The router is denied access by the default rules because:
 +  * Routers are very unlikely to need to send outgoing mail, or collect mail using POP3 or IMAP4, themselves
 +  * Some routers act as proxy servers, so that incoming connections appear to come from the router themselves. This means that if this **DENY** rule was omitted, the default rules would allow access from anywhere on the Internet (including making VPOP3 into an open relay) - this would be very undesirable as a default rule
 +  * If the router's security is compromised, this could allow access into VPOP3 from anywhere on the Internet
 +
 +Note that blocking access from the router does NOT block access from external IP addresses (so it will not conflict with **ALLOW** rules allowing access from outside), unless the router acts like a proxy server, rather than a normal router.
 +
 +Usually there is no need to remove this rule. The only times you would need to do that are if you need the router to send outgoing mail or collect mail itself (which is very unusual), or if your router acts as a proxy server rather than a router (which is also very unusual). In the latter case, you will need to be very careful, and set up any access rules and anti-relay rules on the router itself. (You may need to change the router if you need external access and the router does not support this)
 +
 +The deny rule does NOT (with the other default settings) prevent the router from sending internal email via VPOP3, e.g. for error reports or intrusion notifications.
 +
 +(Note that, nowadays, it is very rare for routers to act like proxy servers, but it was more common several years ago. If in doubt, presume it does not act this way)
  
  
how_to/vpop3_access_security.txt · Last modified: 2018/11/14 10:45 by 127.0.0.1