Environment
Novell GroupWise 5.5
Novell GroupWise 5.5 EP
Novell GroupWise Internet Agent
Novell GroupWise 5.5 EP
Novell GroupWise Internet Agent
Situation
Configure the GroupWise Internet Agent's dial-up SMTP feature
Resolution
For additional information refer to the GroupWise Internet Agent Guide, and click on Appendix C: Configure Dial-up Connectivity with MPR.
I. Prerequisites: A. The dial-up router must connect any time IP traffic is addressed to the Internet. (i.e. Pinging Internet IP addresses from the computer where the GroupWise Internet Agent is running must cause the router to dial.) B. An ESMTP host must be available on the Internet to receive mail when the GroupWise Internet Agent is off-line. Permission should be obtained from the ESMTP host's administrator to use it as a secondary mail host for the GroupWise Internet Agent's mail domain. II. GroupWise Internet Agent Configuration: A. Select the Schedule tab in the GroupWise Internet Agent object. Select the default profile and click edit. Set the message and time threshold as desired. If different thresholds are desired during certain hours, create a new profile for those hours. B. Select the Advanced setting tab in the GroupWise Internet Agent object. Set the following fields to the given values: 1. "Dial-up: use dial connection" should be set to ON. 2. "Dial-up ETRN host" should be set to the hostname or IP address of the ESMTP host that will serve as the back-up mail host for the GroupWise Internet Agent. 3. "Dial-up ETRN queue " should be set to the site's e-mail domain. (The part of an email address to the right of the @ sign.) Contact your ISP to find out what name they have given to the ETRN queue. C. In order for the ETRN command to be sent to the ISP, the Polling Interval must be set to something other than 0. To set the Polling Interval do the following: 1. Go to details of the GWIA NDS object. 2. Select the Schedule button 3. Edit the *Default profile and set the Polling Interval to some setting other than 0. Note: A restart command should be issued to GWIA for this change, otherwise unload and restart GWIA. Steps 4 and 5 are only necessary if Windows NT's RAS is acting as the dial- up router and the GroupWise Internet Agent is running on a different machine. 4. "Dial-up: userid" should be the RAS Security user name. 5. "Dial-up: password" should be the RAS Security password. III. DNS configuration: A. For your e-mail domain, publish an MX record pointing to the hostname of the GroupWise Internet Agent. B. For your e-mail domain, publish an MX record pointing to the hostname of the ESMTP host. C. Make the GroupWise Internet Agent the preferred host by making the preference number of the GroupWise Internet less then the preference number of the ESMTP host. ********** The GroupWise Internet Agent Dial-Up SMTP Concepts ****************************** Motivation: Many GroupWise administrators would like to provide their users with the ability to send and receive Internet E-mail without paying for a constant connection to the Internet. SMTP Review: The GroupWise Internet Agent takes advantage of Internet mail clients using the following procedure when sending mail. 1. The recipient's address is divided into two parts. The user portion (the part to the left of the @ sign) is ignored by the client, and the domain name (the part to the right of the @ sign) is used to determine where the message should be sent. 2. The client then asks DNS for a list of mail exchangers (DNS refers to mail hosts as "mail exchangers") that accept mail for the recipient's domain. Each item in this list is called an MX record and is composed of the domain name, the preference value, and the hostname of the mail exchanger. Such a list for the domain foo.com might look like this: foo.com preference=100, mail exchanger = mail.okdirect.com foo.com preference=50, mail exchanger=smtp.foo.com 3. The mail client will then try to send the message to the mail host with the lowest preference. If the sender can not communicate with the preferred host, it will try sending the message to the next preferred host. The sender continues through the list until it finds someone who will take the message. 4. If none of the mail hosts are reachable, the sender will try to find a host with the same name as the domain. 5. Finally, if that fails, the sender will give up and put the message in a defer queue. 6. Steps 1-5 are repeated for the next three days at regular intervals. 7. After three days, the messages are discarded. Challenge: SMTP was developed for the US Department of Defenses's ARPnet (known today as the Internet) with the assumption that every host is always on line. SMTP's point-to-point architecture exploited this constant connectivity; messages were sent directly from the source host to the destination host or not at all. As the Internet expanded from the original military sites and affiliated research universities to include many small business and individuals, the need for transient access to the Internet increased. SMTP, however, made little provision for dial-up hosts. If a destination host was unavailable, the sending host held the message in a queue, and tried to resend them in regular intervals for three days. This became problematic because by definition, dial-up hosts try to minimize their connection time, making the sender's chance of catching them on line minimal. In a best case scenario, the message was delivered late, and in the worst case, it was not delivered at all. Solution Requirements: The solution must be able to guarantee a mail host will always be on line to ensure that no in-bound messages are lost. A second mail host can be added to act as a backup for the first mail host. Then some mechanism must be put in place to get the mail from the back-up mail host to the primary mail host. Configuring a backup mail host: 1. Get permission to use a mail host that is already permanently part of the Internet. Most ISPs have mail hosts that can be configured to be a back-up for another domain. Some older mail hosts may not support the ETRN command, so take the time to verify that the back-up mail host supports it. (See RFC-1985 for details). 2. Publish a second MX record for the domain name that points to the ISP's mail server. Make sure that the preference number is higher than the preference number for the GroupWise Internet Agent. Example: If the GroupWise Internet Agent for the domain foo.com is running on a server named gwia.foo.com, the first MX record will look like this: foo.com preference=10, mail exchanger=gwia.foo.com If the back-up mail host has a hostname of mail.genericISP.net, the second MX record will look like this: foo.com preference=30, mail exchanger=mail.genericISP.net The most important point to remember about the preferences is that the preferred mail host has the lowest number. It does not matter what the exact number is. Once these MX records are published, mail sent to foo.com will always have a place to go. If gwia.foo.com happens to be on line, the message will go directly there. If it is not on line, mail.genericISP.net will take the message, put it in a queue, and try re-sending it to mail.foo.com periodically. Getting mail from the back-up to the primary: There is still no guarantee that the back-up mail host's normal retry schedule will correspond to the times when the preferred mail host (GWIA) is on line. The GroupWise Internet Agent solves this problem by sending the ETRN command to the back-up host every time it sends outbound mail. This network traffic causes the dial-up router to establish its Internet connection. The ETRN command promptly arrives at the back-up host, causing the queued messages to be resent. With the current connection, the messages get delivered to the GroupWise Internet Agent. Optimizing connection time: By default, the GroupWise Internet Agent assumes that it is constantly connected to the Internet, sending messages out as soon as they are created. If the ISP charges by the total connection time, the GroupWise Internet Agent's money saving Dial-up: use dial connection should be set to on. This setting puts outbound messages in queue and then sends them out in bunches according to schedule configured in NWADMINNT or NWADMIN95. When set to on, the ETRN command is also sent to the back-up mail host every time a burst of messages are sent. Inbound messages that have arrived at the back-up host can then be forwarded while the connection is up. Who does the dialing? The GroupWise Internet Agent does not know how to talk to a modem, an ISDN card, or even an Ethernet card; it simply creates packets and hands them to the IP stack. The network is responsible for getting the packets to their destination. If the destination IP address belongs to an Internet host, a router must be configured to dial the ISP. Network applications like a intraNetWare's NIAS (See KB 2916037 on Novell Support Connection for installation instructions) or WNT's RAS (See Microsoft's web page for more documentation) are just two of the many products that can manage these dial-up responsibilities. The router will almost always require a static IP address. Two conditions must be met to use a dynamically assigned IP address: 1. The GroupWise Internet Agent must be running on a different machine that does have a static address. 2. The ISP's router is configured to route packets destined to the GroupWise Internet Agent through the router's dynamically assigned IP address. Putting it together: The following 10 steps illustrate the flow of messages for an imaginary domain called foo.com. 1. Any time messages are sent to user@foo.com, the sender will first try to contact the preferred mail host. 2. When the sender finds that the preferred mail host is not available, it will send the message to the next mail host on the list. 3. The secondary mail host then tries to relay the message as if it were the sender. 4. When the secondary mail host finds that the preferred mail host is not available, it will put the message in a deferred queue. 5. Any other incoming messages will follow steps 1-4. 6. Internet mail sent by GroupWise user will be held by The GroupWise Internet Agent until the "send thresholds" are met. 7. When any of the thresholds are met, the GroupWise Internet Agent will send all the held messages at once. At the same time, an ETRN command is sent to the back-up mail host. 8. The router then recognizes that the packets are addressed to the Internet, brings up the connection to the ISP, and forwards all the IP packets. 9. When the mail host receives the ETRN command, it will resend the queued messages. (Because the preferred mail host is now on line, the messages will get delivered.) 10. When the router detects that there has been no traffic for a set amount of time (the amount of time will be configured on the router), it will drop the connection, and steps 1-10 will be repeated..
I. Prerequisites: A. The dial-up router must connect any time IP traffic is addressed to the Internet. (i.e. Pinging Internet IP addresses from the computer where the GroupWise Internet Agent is running must cause the router to dial.) B. An ESMTP host must be available on the Internet to receive mail when the GroupWise Internet Agent is off-line. Permission should be obtained from the ESMTP host's administrator to use it as a secondary mail host for the GroupWise Internet Agent's mail domain. II. GroupWise Internet Agent Configuration: A. Select the Schedule tab in the GroupWise Internet Agent object. Select the default profile and click edit. Set the message and time threshold as desired. If different thresholds are desired during certain hours, create a new profile for those hours. B. Select the Advanced setting tab in the GroupWise Internet Agent object. Set the following fields to the given values: 1. "Dial-up: use dial connection" should be set to ON. 2. "Dial-up ETRN host" should be set to the hostname or IP address of the ESMTP host that will serve as the back-up mail host for the GroupWise Internet Agent. 3. "Dial-up ETRN queue " should be set to the site's e-mail domain. (The part of an email address to the right of the @ sign.) Contact your ISP to find out what name they have given to the ETRN queue. C. In order for the ETRN command to be sent to the ISP, the Polling Interval must be set to something other than 0. To set the Polling Interval do the following: 1. Go to details of the GWIA NDS object. 2. Select the Schedule button 3. Edit the *Default profile and set the Polling Interval to some setting other than 0. Note: A restart command should be issued to GWIA for this change, otherwise unload and restart GWIA. Steps 4 and 5 are only necessary if Windows NT's RAS is acting as the dial- up router and the GroupWise Internet Agent is running on a different machine. 4. "Dial-up: userid" should be the RAS Security user name. 5. "Dial-up: password" should be the RAS Security password. III. DNS configuration: A. For your e-mail domain, publish an MX record pointing to the hostname of the GroupWise Internet Agent. B. For your e-mail domain, publish an MX record pointing to the hostname of the ESMTP host. C. Make the GroupWise Internet Agent the preferred host by making the preference number of the GroupWise Internet less then the preference number of the ESMTP host. ********** The GroupWise Internet Agent Dial-Up SMTP Concepts ****************************** Motivation: Many GroupWise administrators would like to provide their users with the ability to send and receive Internet E-mail without paying for a constant connection to the Internet. SMTP Review: The GroupWise Internet Agent takes advantage of Internet mail clients using the following procedure when sending mail. 1. The recipient's address is divided into two parts. The user portion (the part to the left of the @ sign) is ignored by the client, and the domain name (the part to the right of the @ sign) is used to determine where the message should be sent. 2. The client then asks DNS for a list of mail exchangers (DNS refers to mail hosts as "mail exchangers") that accept mail for the recipient's domain. Each item in this list is called an MX record and is composed of the domain name, the preference value, and the hostname of the mail exchanger. Such a list for the domain foo.com might look like this: foo.com preference=100, mail exchanger = mail.okdirect.com foo.com preference=50, mail exchanger=smtp.foo.com 3. The mail client will then try to send the message to the mail host with the lowest preference. If the sender can not communicate with the preferred host, it will try sending the message to the next preferred host. The sender continues through the list until it finds someone who will take the message. 4. If none of the mail hosts are reachable, the sender will try to find a host with the same name as the domain. 5. Finally, if that fails, the sender will give up and put the message in a defer queue. 6. Steps 1-5 are repeated for the next three days at regular intervals. 7. After three days, the messages are discarded. Challenge: SMTP was developed for the US Department of Defenses's ARPnet (known today as the Internet) with the assumption that every host is always on line. SMTP's point-to-point architecture exploited this constant connectivity; messages were sent directly from the source host to the destination host or not at all. As the Internet expanded from the original military sites and affiliated research universities to include many small business and individuals, the need for transient access to the Internet increased. SMTP, however, made little provision for dial-up hosts. If a destination host was unavailable, the sending host held the message in a queue, and tried to resend them in regular intervals for three days. This became problematic because by definition, dial-up hosts try to minimize their connection time, making the sender's chance of catching them on line minimal. In a best case scenario, the message was delivered late, and in the worst case, it was not delivered at all. Solution Requirements: The solution must be able to guarantee a mail host will always be on line to ensure that no in-bound messages are lost. A second mail host can be added to act as a backup for the first mail host. Then some mechanism must be put in place to get the mail from the back-up mail host to the primary mail host. Configuring a backup mail host: 1. Get permission to use a mail host that is already permanently part of the Internet. Most ISPs have mail hosts that can be configured to be a back-up for another domain. Some older mail hosts may not support the ETRN command, so take the time to verify that the back-up mail host supports it. (See RFC-1985 for details). 2. Publish a second MX record for the domain name that points to the ISP's mail server. Make sure that the preference number is higher than the preference number for the GroupWise Internet Agent. Example: If the GroupWise Internet Agent for the domain foo.com is running on a server named gwia.foo.com, the first MX record will look like this: foo.com preference=10, mail exchanger=gwia.foo.com If the back-up mail host has a hostname of mail.genericISP.net, the second MX record will look like this: foo.com preference=30, mail exchanger=mail.genericISP.net The most important point to remember about the preferences is that the preferred mail host has the lowest number. It does not matter what the exact number is. Once these MX records are published, mail sent to foo.com will always have a place to go. If gwia.foo.com happens to be on line, the message will go directly there. If it is not on line, mail.genericISP.net will take the message, put it in a queue, and try re-sending it to mail.foo.com periodically. Getting mail from the back-up to the primary: There is still no guarantee that the back-up mail host's normal retry schedule will correspond to the times when the preferred mail host (GWIA) is on line. The GroupWise Internet Agent solves this problem by sending the ETRN command to the back-up host every time it sends outbound mail. This network traffic causes the dial-up router to establish its Internet connection. The ETRN command promptly arrives at the back-up host, causing the queued messages to be resent. With the current connection, the messages get delivered to the GroupWise Internet Agent. Optimizing connection time: By default, the GroupWise Internet Agent assumes that it is constantly connected to the Internet, sending messages out as soon as they are created. If the ISP charges by the total connection time, the GroupWise Internet Agent's money saving Dial-up: use dial connection should be set to on. This setting puts outbound messages in queue and then sends them out in bunches according to schedule configured in NWADMINNT or NWADMIN95. When set to on, the ETRN command is also sent to the back-up mail host every time a burst of messages are sent. Inbound messages that have arrived at the back-up host can then be forwarded while the connection is up. Who does the dialing? The GroupWise Internet Agent does not know how to talk to a modem, an ISDN card, or even an Ethernet card; it simply creates packets and hands them to the IP stack. The network is responsible for getting the packets to their destination. If the destination IP address belongs to an Internet host, a router must be configured to dial the ISP. Network applications like a intraNetWare's NIAS (See KB 2916037 on Novell Support Connection for installation instructions) or WNT's RAS (See Microsoft's web page for more documentation) are just two of the many products that can manage these dial-up responsibilities. The router will almost always require a static IP address. Two conditions must be met to use a dynamically assigned IP address: 1. The GroupWise Internet Agent must be running on a different machine that does have a static address. 2. The ISP's router is configured to route packets destined to the GroupWise Internet Agent through the router's dynamically assigned IP address. Putting it together: The following 10 steps illustrate the flow of messages for an imaginary domain called foo.com. 1. Any time messages are sent to user@foo.com, the sender will first try to contact the preferred mail host. 2. When the sender finds that the preferred mail host is not available, it will send the message to the next mail host on the list. 3. The secondary mail host then tries to relay the message as if it were the sender. 4. When the secondary mail host finds that the preferred mail host is not available, it will put the message in a deferred queue. 5. Any other incoming messages will follow steps 1-4. 6. Internet mail sent by GroupWise user will be held by The GroupWise Internet Agent until the "send thresholds" are met. 7. When any of the thresholds are met, the GroupWise Internet Agent will send all the held messages at once. At the same time, an ETRN command is sent to the back-up mail host. 8. The router then recognizes that the packets are addressed to the Internet, brings up the connection to the ISP, and forwards all the IP packets. 9. When the mail host receives the ETRN command, it will resend the queued messages. (Because the preferred mail host is now on line, the messages will get delivered.) 10. When the router detects that there has been no traffic for a set amount of time (the amount of time will be configured on the router), it will drop the connection, and steps 1-10 will be repeated..
Additional Information
Formerly known as TID# 10007366