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WI B Pt.2: By MAURO GRASSI Web S erver I n a B ox Last month, we introduced our new Web Server In A Box (WIB) and gave the full construction details. This month, we show you how to connect it to your modem/ router and guide you step-by-step through the set-up details. We also show you how to activate a dynamic DNS service, so that you can access the WIB via the Internet. 82  Silicon Chip siliconchip.com.au I N ORDER TO ACCESS the WIB over the internet, you must have an account with an ISP (eg, Telstra, TPG, Optus, etc). You must also have a router connected to the modem or you can use a combined modem/router. In fact, this is the most common set-up where you have more than one device sharing your Internet connection. In summary, the set-up procedure involves the following eight steps: Step 1: Physically connecting the WIB to your network (this involves connecting it via an ethernet cable to your router or modem/router). Step 2: Changing the DHCP range of your modem/router (ie, the range of IP addresses it can automatically assign to other devices on the network) to prevent conflicts with the static IP assigned to the WIB. Step 3: Enabling port forwarding (or virtual server) in your modem/router for the HTTP and FTP servers. Step 4: Directly copying the provided website and configuration files onto the WIB’s memory card using a PC. Step 5: Modifying the settings.txt file so that you can connect to the WIB via the local network using your web browser. Step 6: Configuring each module in turn by changing the settings via the browser. These modules are: (a) the HTTP (web) server; (b) the SNTP client (for network time); (c) the FTP server (to allow files to be uploaded or downloaded); (d) the SMTP email client (for email notifications); and (e) dynamic DNS (domain name server) to allow access via the Internet. Step 7: Setting up the analog variables, so that you can monitor the analog sensors (eg, for temperature). Step 8: Creating new default values once the set-up is finished. Step 1: Connecting The WIB To Your Modem/Router T HERE ARE several ways of connecting this device to your local network. First, if you have combined modem/router with a spare ethernet port, then it’s simply a matter of connecting the WIB to it using a straightthrough ethernet cable as shown in Fig.9(a). Alternatively, if the router is separate, then the WIB should be plugged into this along with the modem as shown in Fig.9(b). If you don’t have a spare ethernet port on your modem/router, then the connection will have to be made via a network hub. This situation will typically arise if you only have one port on a combined modem/router siliconchip.com.au 192.168.0.34 ETHERNET PORT WIB (FIXED IP ADDRESS) MODEM/ ROUTER INTERNET DYNAMIC IP ADDRESS ETHERNET PORT PC (DYNAMIC IP ADDRESS) A FIXED LOCAL IP ADDRESS (EG, 192.168.0.1) MODEM/ROUTER WITH AVAILABLE ETHERNET PORT Fig.9(a): here’s how to connect the WIB to your local network if you have a combined modem/router (be sure to use straight-through ethernet cable). If your modem/router uses a 10.x.x.x fixed IP address, then you will have to change the IP address of the WIB accordingly (eg, if the modem,router uses 10.0.0.1, then change the WIB’s address to 10.0.0.34). December 2009  83 Step 1 CONTINUED . . . ETHERNET PORT DYNAMIC MODEM IP ADDRESS Fig.9(c) (below): this is the scheme to use if your modem/router has only one ethernet port but that’s normally taken by your PC or some other device. In that case, you need to connect both the PC and the WIB to separate ports on a hub. The modem/router is then connected to another port. The WIB’s IP address should normally be outside the DHCP range (see text). INTERNET FIXED LOCAL IP ADDRESS (EG, 192.168.1.1) MODEM PORT (EG, 192.168.1.2) 192.168.0.34 ETHERNET PORT (LAN) WIB (FIXED IP ADDRESS) ETHERNET PORT ROUTER B FIXED LOCAL IP ADDRESS (EG, 192.168.0.1) SEPARATE MODEM & ROUTER WIB (FIXED IP ADDRESS) Fig.9(b) (above): if the modem and router are separate, then connect the WIB as shown here. As before, use straight-through ethernet cable to make the connections and change the WIB’s IP to suit the network if the inward facing (local) IP of the router uses a 10.x.x.x address or some other addressing scheme. but that’s already used to connect your PC. In that case, the PC will have to be disconnected from the modem/router and both it and the WIB connected via a hub as shown in Fig.9(c). INTERNET ETHERNET PORT ETHERNET PORT 192.168.0.34 (DYNAMIC IP ADDRESS) DYNAMIC IP ADDRESS FIXED LOCAL IP ADDRESS (EG, 192.168.0.1) ETHERNET PORT (LAN) PC MODEM/ ROUTER HUB ETHERNET PORT PC (DYNAMIC IP ADDRESS) C MODEM/ROUTER WITH A SINGLE ETHERNET PORT Note that, in all cases, we’re assuming that the PC is assigned a dynamic IP address by the DHCP server in the router. Alternatively, it can be configured with a static IP. The default static IP of 192.168.0.34 for the WIB is also shown but this can be changed to suit the network if necessary, as we shall see later. Note that all the connections are made using straight-through ethernet cable (usually blue). Step 2: CHANGING THE MODEM/ROUTER’s DHCP RANGE I N MOST NETWORKS, a DHCP server in the modem/router is used to hand out dynamic IP addresses to any devices on that network. By contrast, the WIB uses a fixed IP address. As a result, the DHCP range must be restricted to avoid this address, to prevent conflicts. Alternatively, you can reserve a fixed (static) IP address for the WIB within the DHCP server range. Again, this prevents it from handing out the WIB’s IP address to some other device on the network. If you leave the WIB’s IP at the default 192.168.0.34, the easiest approach in most cases is to restrict the DHCP range so that is covers from 192.168.0.2 to 192.168.0.33. Alterna84  Silicon Chip tively, or you can specify that DHCP addresses start from 192.168.0.35. The first step is to log into your router using a web browser. Your router has a fixed IP address on the network (192.168.0.1 is a common default) and this is often (but not necessarily) the address that’s also used to access its set-up pages (this can be checked in the router’s manual). You will also need the username and the password for the modem/router. In the case of a D-Link DI-524, for example, the set-up address is the same as the LAN address and it’s just a matter of entering 192.168.0.1 in the browser, followed by the username and password at the login prompt. The default username and password differ according to the manufacturer but in any case, you should have changed these for security reasons when you first set up your modem/router. Once logged in, you then navigate to the DHCP set-up page and set up the DHCP address range. Make sure that the IP address of the WIB falls outside this range, to avoid any conflicts. You will need to specify a big enough address range to accommodate all the devices on your network that rely on DHCP. You then save the settings and reboot your modem/router to make the settings stick. An example screen grab using a D-Link DI-524 router is shown in Fig.10, while Fig.11 shows the settings for a Motorola SBG900 siliconchip.com.au Fig.10: configuring the DHCP server range in the D-Link DI-524 modem/router. Note that, for most modem/ routers, the WIB’s address should be outside this range. cable modem/router. Note that the latter has a fixed network address of 192.168.0.1 but its set-up is accessed using 192.168.100.1. For the Motorola SBG900, it’s a matter of navigating to Gateway – LAN – DHCP Server Config and entering in the starting IP address and the number of DHCP users (see Fig.11). Unlike most other modem/routers though, the DHCP range here must include the WIB’s IP address otherwise you will not be able to configure port forwarding later on (see below). You must then reserve a fixed IP address for the WIB and for any other device with a fixed IP that falls within the DHCP range. That’s done by associating an IP address with the MAC address of each such device – see Fig.12. You can discover the MAC address of each device on a network by entering ipconfig /all at a command prompt. The MAC address of the WIB is also indicated on its Basic Settings page – just enter 192.168.0.34/basic.cgi in a web browser and log in (admin and pass are the default username and password entries respectively). Don’t forget to reboot the modem after making these changes, so that the settings take effect. Fig.11: the DHCP server configuration for the Motorola SBG900 cable modem/router. Unlike the set-up for most other units, the DHCP range in this case must include the WIB’s IP address to allow port forwarding. The WIB’s static IP address is then reserved – see below. Fig.12: the WIB’s static IP address (along with the fixed IP of any other device) is reserved in the SBG900 as shown here. It’s done by assigning a fixed IP to the MAC address of each device – see text. Step 3: CONFIGURING Port Forwarding & THE Firewall T HE ADDRESS assigned to the modem by your ISP is known as the “public IP address”. This is the address that’s presented to the Internet. At the same time, the modem (or modem/router) also has a private (inward facing) IP address which it siliconchip.com.au presents to the home network – see Figs.9(a), 9(b) & 9(c). In operation, the router stores information on the outgoing packets and then uses this information to determine where to route the response on the home network. This is called Network Address Translation or NAT. NAT also acts as a kind of firewall, since any unsolicited requests from outside are dropped by the router. However, in this case, we want HTTP and FTP requests directed at December 2009  85 Step 3 CONTINUED . . . Fig.13: port forwarding set-up on the Motorola SBG900 modem/router. Unlike the D-Link DI-524, it allows you to specify a port range. Fig.12: virtual server set-up in the D-Link DI-524. Ports 80, 20 & 21 (all TCP protocol) must be forwarded to the WIB’s IP address and these ports, along with ports 25 (TCP) & 123 (UDP), must also be open in the firewall. the public IP address (ie, from the Internet) to be forwarded to the WIB’s private IP address. This is where “port forwarding” comes in. Port forwarding is a way of making your router redirect incoming traffic on a particular port to a private IP address on your home network. In this case, to access the WIB’s website from the Internet, we need to redirect incoming traffic on HTTP port 80 to the WIB’s static IP address. In addition, you also need to redirect traffic on the common FTP ports (20, 21) to provide FTP access from the Internet. Port forwarding goes under different names and some routers may call it “virtual server” instead. You will need to log into your router using a web browser to change the port forwarding settings. For web access, you need to enable forward port 80 to 192.168.0.34 while to enable FTP access, you need to forward ports 20 & 21 to the address. Example set-ups Let’s take a look at a couple of example set-ups, the first being for a D-Link DI-524 router (the procedure for your modem/router will be similar). As explained previously, the DI-524’s set-up pages are accessed by entering 192.168.0.1 (ie, the same as its private IP address) into a web browser. You then enter the username and password to log in. Once logged in, it’s then just a matter of clicking the Virtual Server button and defining entries to portforward TCP port 80 (for HTTP) and TCP ports 20 & 86  Silicon Chip Fig.14: setting up port forwarding automatically adjusts the firewall settings on some modem/routers but this must be done manually in the SBG900. Ports 20, 21 & 80 (TCP) must be opened in both directions, while ports 25 (TCP) & 123 (UDP) must be opened in the outbound direction only. siliconchip.com.au 21 (for FTP) – see Fig.12. In each case, they should be forwarded to the static IP address of the WIB (eg, 192.168.0.34). Note that FTP ports 20 & 21 have to be defined separately here. Alternatively, some modem/routers let you define a port range. Once port forwarding has been enabled for HTTP and FTP you will probably have to reboot the router for the changes to take effect. Fig.13 shows the corresponding port forwarding settings for the Motorola SBG900 cable modem. Unlike the D-Link DI-524, this modem lets you define a port range, so we only need a single entry for FTP (ie, port range 20-21). Note that if you have a separate modem and router, you will have to turn on port forwarding (or change the virtual server settings) for each. It won’t work if you only do it for the modem, for example, since the router would then drop any incoming requests. For example, let’s say that you have a modem with an internal IP address of 10.0.0.1 and a router with a matching external address of 10.0.0.3 (ie, on its modem port) and an internal address of 192.168.0.1. In that case, you configure the modem to forward ports 20, 21 & 80 to 192.168.0.1. The router is then configured to forward these ports to the WIB’s private IP address (eg, to 192.168.0.34). Check the firewall Once you’ve turned on port forwarding, you also need to make sure that the relevant ports are opened in the firewall. On some modem/ routers, this happens automatically when port forwarding is enabled (eg, D-Link DI-524). By contrast, on the Motorola SBG900, you have to open the relevant ports yourself. The protocol to use for both HTTP and FTP is TCP and you have to allow traffic in both directions. In addition, you have to open port 123 to allow NTP (or SNTP) requests to an Internet time server. In this case, the allowed protocol must be UDP and you only need to allow outbound requests – see Fig.14. You will have to do this, regardless as to what type of modem/router you have. Check also that port 25 (SMTP) is open for outgoing TCP packets, otherwise the WIB will not be able to send email (this port will already be open if you are successfully using a PC to send email). As with port forwarding, if you have a separate modem and router, you have to configure the firewall on each. Alternatively, turn one of the firewalls off – you don’t need both. Step 4: Copying Files To The Memory Card T HIS STEP involves copying the provided website files and the default settings file to the memory card. You will need a compatible memory card and a card reader so that you can read and write to the card using a PC. Many laptops are equipped with card readers as standard or you can use an external card reader with a USB interface like those shown last month. You can use any MMC, SD or SDHC memory card to store the files, since all three types are compatible with the WIB. The memory card must be formatted to the FAT/FAT32 file system. If it uses some other file system, then it will have to be reformatted (just right-click the drive and click “Format”). Note that you may want to back up whatever was on the card before you do this, because formatting will erase everything that’s on it. Next, download the file ewswebsite.zip from the December 2009 download section on the SILICON CHIP website. Unzip this file’s contents and then copy all the unzipped files directly to the memory card’s siliconchip.com.au Fig.15: the WIB’s website files must be downloaded (in ewswebsite.zip) from the SILICON CHIP website and copied to the memory card. root folder. After this is done, your memory card’s root folder should look like the screen grab shown in Fig.15. December 2009  87 Step 5: Configuring Minimal Settings H AVING COPIED the files to the memory card, the next step is to open the settings.txt file in a text editor and enter in a few basic (or minimal) settings. These are the settings that are necessary for you to access the WIB using a web browser (ie, when the card is installed in the WIB). First, you need to determine the gateway address of your network. This is the LAN (local area network) IP address of your router. Typically, this will be either 192.168.0.1 or 192.168.1.1 but other numbers are also commonly used (eg, 10.0.0.1), depending on the router. The default IP will be listed in the router’s manual and can also be checked by accessing the router’s set-up pages. It can also be discovered by entering the command ipconfig /all in a Command Prompt window on your PC. The resulting dialog will show not only the gateway address but also the IP addresses of other devices on the network, the subnet mask, the device MAC addresses and the addresses of your ISP’s DNS servers. As a minimum, the WIB must be provided with the following information to get it working on your home network: • IP Address: this is the address of the WIB and should be an unused address on your home network. As stated previously, the default value is 192.168.0.34 but change this to suit your network if necessary (eg, if you are using 10.x.x.x network IP addresses). If your network uses DHCP to hand out IP addresses, then you must follow the procedure described in Step 2 to restrict the DHCP range or to reserve a static (or fixed) IP addresses for the WIB, to avoid conflicts. Alternatively, you can reserve a range of fixed addresses and any address in this range can be then be used for the WIB. • Gateway Address: this is the IP address that the WIB uses to communicate with the Internet. This is simply the LAN IP address of your router (typically 192.168.0.1) and can be checked as described above. • Subnet Mask: this is the mask that determines your home network’s subnet. This will typically be set to 255.255.255.0 (the default) but some networks might require 255.255.0.0. • Primary DNS Server: this can usually simply be set to the IP address of the router (ie, the same as the Gateway Address). In some cases though, it may be necessary to enter in the Fig.17: the WIB’s home page displays the analog input values and lets you toggle the digital outputs on or off. You can also send data to the serial port. 88  Silicon Chip Fig.16: the log-in dialog box for the WIB’s website. Be sure to change the default username and password. address of your ISP’s primary DNS server, as some routers don’t function as DNS relays. In particular, if the WIB fails to pick up network time later on, try entering your ISP’s primary DNS server address here. Once again, use the command ipconfig /all to discover the DNS addresses if necessary. • Username: this is the username that’s used to log into the WIB’s HTTP server (and also to log into the FTP server). The default is “admin”. • Password: this is the password that’s used to log in to the WIB. The default is “pass”. The settings are each entered on a separate line and it should look like this (default values shown): IP Address = 192.168.0.34 Gateway = 192.168.0.1 Subnet Mask= 255.255.255.0 Primary DNS = 192.168.0.1 User = admin Password = pass Replace the values as appropriate using a text editor on your PC and save the changes to the memory card. As a minimum, you should replace the default “user” and “password” values. The security of the WIB depends on the username and password not being easy to guess, otherwise you could get an unwanted guest logging in and inspecting your email set-up details. Once you’ve modified the above parameters in the settings.txt file, eject the memory card from the reader and insert it into the WIB (it can only go in one way). The remaining entries in the settings.txt file are left as they are, since further changes are now made by accessing the WIB using your web browser. The resulting siliconchip.com.au changes are then saved in a separate binary file called values.dat. With the memory card now in place (and the unit connected to your router), apply power and check the orange and green front panel LEDs. These should both light for a few seconds and then the green LED should go out while the orange LED should flash at a 0.5s rate (ie, twice a second), indicating that the unit has “booted”. The green LED inside the RJ45 connector should be lit (indicating a valid ethernet link) and you should also occasionally see the yellow LED in the RJ45 connector light (ie, when data is being transferred). If it all checks out so far, launch your web browser (Internet Explorer, Opera, Firefox, Safari, Chrome, etc), type 192.168.0.34/home.cgi in the address bar and press Enter (note: be sure to use the correct IP address for the WIB if you’ve changed it from the default IP). A login window should now appear – see Fig.16. Next, enter your username and password and click OK. The WIB’s home page should now appear (Fig.17). This shows the values of the four analog inputs and the state of the four digital outputs. The latter are all off (logic 0) by default but you can toggle then by clicking the Toggle buttons. You now use the WIB’s website to change all the other settings and we’re going to do that right now. Step 6: Configuring The Modules T HIS STEP involves configuring each module of the TCP/IP stack in turn, beginning with the Basic Settings. Before we start though, note that each time you change an entry here, you must click its associated “Change” button to store the value in the values.dat file. The WIB must also then be restarted for any changes to take effect (ie. by clicking the “Master Reset” button. • Basic Settings: begin by clicking on the Basic link to bring up the page shown in Fig.18. This should show all the settings you entered at Step 5, so there should be little (if anything) to do here. However, you may wish to set a secondary DNS server (to act as a backup if the primary DNS server is temporarily out). To do this, simply enter its IP address and click the “Change Secondary DNS” button. Don’t forget to reboot the WIB for the setting to take effect. • HTTP Settings: Fig.19 shows the HTTP Settings page. However, before going further, we should emphasise that the default values will be suitable for most users and can be left just as they are. The HTTP file extension and permission settings should be modified only by advanced users who wish to customise the behaviour of the WIB. If necessary, you can change the HTTP port number (default 80) and the file extensions, contents and siliconchip.com.au Fig.18: the Basic Settings page should show all the settings you entered into the settings.txt file in Step 5 but you can make further changes here. permissions to determine whether files are available for public or private access. Basically, each file that is served by the WIB is treated differently, according to its extension. If the file has one of the 12 user-defined extensions, it’s assigned the corresponding user-defined file permissions and content type. If not, it’s given the default content type and file permission. The content type is specified in the HTTP header and is known as a “MIME-file” extension. This allows non-html files to be opened in a web browser, eg, pdf and gif files. Basically, the content type affects how the browser opens, transfers and displays the file. Note that the file permissions allocated to a particular file extension apply to all files with that file extension. There are three file permissions and these are as follows: December 2009  89 Step 6 CONTINUED . . . (1) Public/Private: this determines whether or not a user needs to log in to access a particular file type on the WIB. If a file type is public, then anyone can access those files without logging in. For example, if pdf files are public and there’s a file on the WIB called report.pdf, then that file can be accessed simply by entering IPaddress/report.pdf in the address bar of a web browser. In this case, IPaddress is either the public IP address of the modem if the user is accessing the WIB via the Internet or the fixed IP address of the WIB itself if access is via the local network (ie, 192.168.0.34/report.pdf). Note that because the file type is public, no log-in would be required. Similarly, if a hostname has been assigned (as described in the Dynamic DNS section below), then the user would simply enter hostname/ report.pdf in the address bar. Conversely, if a file type is private, then the user will be required to log in order to gain access. In fact, special system files should be made private so as to not compromise the system’s security. These include the settings.txt file, the log.txt file and the values.dat file. All three contain password information that should not be public. So, as a minimum, the “txt” and “dat” extensions should be private (ie, you should leave them at the default settings). Note that cgi files are also made private by default. This setting should be left as it is if you intend using the website cgi files we have provided for the WIB. Alternatively, you might want to make cgi files public if you create your own web pages with active content. As shown in Fig.19, quite a number of file types are made public by default, including pdf, jpg, gif and wav. However, you might want to change all these file types to private, so that no pages are accessible unless the user logs in using a username and password. (2) Static/Dynamic: this file permission determines whether the page contains dynamic content or fixed content. This affects whether the web server replaces dynamic content references or only serves a static page (we’ll explain this next month in Pt.3). (3) Executable/Non-executable: this permission specifies whether or not you can execute the commands on html forms. This should be set to Executable for file extensions that contain (modified) CGI command references – see Pt.3 next month for an explanation of how commands are implemented. Once again, the default settings will be suitable in nearly all cases. • In order for the SNTP client to work, you must have a valid DNS server address entered in the Basic Settings. You can usually just use the Gateway Address (eg, 192.168.0.1) here but if the NTP client fails to pick up the correct time, use your ISP’s DNS server address. Begin by clicking on the SNTP link to bring up the page shown in Fig.20. The default time server value is pool.ntp.org but there are lots of other NTP servers on the Internet and you can change the default server to any of these. The default port number is 123. This will only need to be changed in rare circumstances and then only if you have advanced knowledge of port forwarding. Note that the time obtained by SNTP is UTC (Coordinated Universal Time) time. This means that Fig.19: the HTTP Settings page lets you set the file permissions. Do not modify the default values unless you know exactly what you are doing. SNTP Settings: this page sets up the SNTP client so that it accesses an Internet time server (eg, to timestamp logging entries). The “epoch time” is the reference for SNTP and the 32-bit number returned as a result of a time query is the number of seconds that have elapsed since this reference time. For a typical NTP server, this is set at 00:00 on January 1, 1970. 90  Silicon Chip siliconchip.com.au you need to specify an offset value, depending on your geographical location, to convert to local time. The east coast of Australia (Sydney, Brisbane, Melbourne) is 36,000 seconds (ie, 10 hours) ahead of UTC and so 36000 is the default value here. Adelaide and Darwin are 9.5 hours ahead of UTC, so the value to use is 34200. The offset for Perth is 25200 (ie, 7 x 60 x 60). In practice, it’s just a matter of checking how far your region is ahead of UTC time and entering the value in seconds accordingly. Note that if you live in a part of the world that is behind UTC (eg, Canada & the US), you have to specify a negative number. For example, if you are four hours behind UTC, you would specify an offset value of -14400. Finally, the NTP page has provision for you to enter in the start and Fig.20: the default NTP server and port values will be suitable in most cases. Enter in an offset value to suit your time zone and the daylight saving details. end dates for daylight saving, so that the time automatically adjusts. You also need to enter the daylight sav- ing offset (eg, 3600 seconds for one hour). Setting this offset to “0” turns daylight saving off. • FTP Settings: clicking the FTP link brings up the page shown in Fig.21. The default port values shown here for the FTP server (ie, 20 & 21) should generally be left as they are but some advanced users might want to change them under certain circumstances. The timeout is the amount of time that is allowed to elapse without activity before the client is disconnected. This is an automatic logout in case you forget to do so. The default is 600s (10 minutes). There are many FTP client programs for Windows and other operating systems but many of these won’t work with the WIB because it doesn’t implement the full FTP command set. The way around this is to use a command line program called ftp. You invoke it from a command prompt simply by typing “ftp x.x.x.x” where x.x.x.x is the IP address of the WIB. If the IP address is valid, you will be prompted for the log-in username and password. As stated, the WIB’s FTP server only implements a subset of the full FTP command set. However, the main commands such as get, put, cd, pwd, dir, delete, user and pass are all available, as are the macro commands mget and mput (batch siliconchip.com.au Fig.21: the default FTP setting can usually be left as they are. Table 1: FTP Commands CD: change directory. PWD: show the current directory. DELETE: delete a file. DIR: show the files in the current directory and the file sizes. LS: show only the name of the files in the current directory. PUT: send a file to the ethernet web server. GET: retrieve a file from the WIB. get and put commands respectively). In particular, the mput command is useful for uploading an entire website to the WIB if you don’t wish to transfer the files directly using a MGET: retrieve a collection of files from the WIB. MPUT: send a collection of files to the ethernet web server. USER: specify the username for login. PASS: specify the password for login. OPEN: open an FTP connection to a remote server. QUIT: exit the current FTP session. PC and a memory card reader. Table 1 sets out the available FTP server commands. We’ll give an example FTP session in Pt.3 next month. December 2009  91 Step 6 CONTINUED . . . Fig.22: the SMTP Settings page. Click the “Email Test” button after entering in all the details, to verify that it works. • SMTP (Email) Settings: clicking this link brings up the dialog shown in Fig.22. This is where you enter your email settings, so that the WIB can send emails. The SMTP port can be left at its default of 25, so start by entering in the address that you want the WIB to send emails to. That done, enter in the hostname of your ISP’s SMTP server. For example, the Bigpond SMTP server is at mail.bigpond.com while the Optus SMTP server is at mail.optusnet.com.au Note that the SMTP server will be specified in your usual email client (eg, Outlook Express), so it’s easy to check. Alternatively, check your ISP’s website for the hostname of their SMTP server. Next, fill in the “Email From” field. This will typically be your name or your email address but you can also use any other name. Finally, enter your email username (usually your full email address) and your email server pass­ word. Don’t forget to click the cor- responding “Change” button as each field is completed. Now click the Email Test button. This allows you to check that your SMTP configuration is valid. If all is well, a test email will be sent each time you click this button and you can verify this by clicking the Basic link and scrolling to the bottom of the system log on that page (note: you may have to reload the page to update the log file from the version cached by your browser). If it doesn’t work, try resetting the WIB after changing the SMTP settings to ensure that the changes have taken effect. This is done by clicking the “Master Reset” button on the Basic page or you can restart the WIB by switching it off and on. Note that an error code is returned on each failed email attempt and this is useful for debugging. Once you’ve got it working, the WIB will start sending email notifications as follows: (a) each time a master reset is performed; (b) when the IP address of the WIB is changed; (c) when an analog input breaches its set limits; and (d) periodically (if enabled) when the required number of log entries is reached. • Dynamic DNS Settings: although the IP address of the WIB itself is fixed (eg, to 192.168.0.34), its public IP address (ie, that presented to the outside world by your modem) may change. This is because most ISPs assign dynamic IP addresses for specific “lease” periods (eg, 12 hours) rather than hand out static addresses. This is a way of making the most of the limited range of IP addresses assigned to a particular ISP. Because the public IP address assigned by your ISP may change, and since this address must be used to access the WIB from anywhere outside your home network, we need a way to automatically keep track of any address changes. A common method for doing this is called “Dynamic DNS” (Dynamic Domain Name System). This is a service that keeps track of a dynamic IP address by associating 92  Silicon Chip Fig.23: the Dynamic DNS Settings page requires entries for the public IP server and the dynamic DNS server. it to a static hostname. For example, you could associate the hostname silchip.redirectme.net to your current dynamic IP address and the system siliconchip.com.au Fig.24: you can set up a dynamic DNS service for the WIB by pointing your web browser to www.no-ip.com will then automatically track any future changes. This is exactly what we need for the WIB so that it can be accessed from the Internet by using its hostname rather than its public IP address. Dynamic DNS will work with a static IP address too. However, in this case, it would not have to keep track of any IP address changes. Instead, you would use the DNS service simply for the convenience of being able to use a hostname rather than an IP address. A dynamic DNS client is built into the WIB, so setting up the service is straightforward. The first step is to set up an account with a dynamic DNS provider at either www.no-ip. com or www.dyndns.com. You will need to sign up to a free account at one of these. Once that is done, the WIB will automatically log in to your account on a regular basis. It will then update its public IP address on the service if it detects it has changed. There may be a delay of up to 10 minutes until the changes are fully propagated but once they are, you will be able to again access the WIB using its fixed hostname. Note that many modem/routers also include a dynamic DNS client. In practice, you could use this siliconchip.com.au Fig.25: once you’ve created an account, log go to www.noip.com/members and click the “Add A Host” button. instead of the one in the WIB but we’ll assume here that you’ll be using the latter. OK, let’s take a look at how you would go about setting up an account at www.no-ip.com Begin by pointing your web browser to http://www.no-ip.com and click the green No-IP Free button – see Fig.24. Type in your email address and click the “Sign Up Now” button, then follow the prompts to create your account. Once you’ve created your account, log in by going to www. no-ip.com/members Your home page will look something like Fig.25. Now click on the “Add A Host” button, type in a hostname of your liking and choose a domain from the list of available names. For example, we chose silchip for the name and redirectme.net for the domain to get the hostname silchip.redirectme.net Now click on the “Create Host” button to complete setting up the dynamic DNS host. Having created the host account, the WIB must now be set up to log into this account when it detects a change in its public IP address. This is done by first clicking on the Dynamic DNS link to bring up the page shown in Fig.23. A number of settings now need to be entered in the Dynamic DNS Settings page, beginning with the public IP server. This is basically an HTTP server that allows you to determine your current public IP address (ie, as assigned by your ISP). A suitable public IP server is at checkip.dyndns.com and this is the default (note: IP servers that return a full html page, such as whatismyip. com, can not be used). Do You Really Need Dynamic DNS? It’s not always necessary to set up a dynamic DNS service. In particular, if you have been assigned a static IP address by your ISP, then the WIB can always be accessed over the Internet using this fixed public address. Similarly, if you have a dynamic IP address, this is unlikely to change if the modem is permanently powered up. And even if the modem is switched off for a short time or there is a power interruption, it will be assigned its previous IP address provided it is within the lease period. So again, depending on you application, you might not want to bother setting up a dynamic DNS. December 2009  93 Step 6 CONTINUED . . . To check this, enter checkip. dyndns.com in the address field of your browser. You should receive a simple html file response containing your public IP address. It will look like this: Current IP Address: 165.221.92.134 except the IP address will almost certainly be different (ie, it will show your current public IP address). So that’s how the WIB determines its public IP address. This discovered address is displayed on the Dynamic DNS Settings page (Fig.23). The public IP server port should be set to 80, which again is the default (it can be changed if necessary by advanced users). For the Dynamic DNS server, you have to enter the hostname of the server for the particular account you’ve just created. If you are using the service at www.no-ip.com, enter dynupdate.no-ip.com as the server. Alternatively, if you are using the service at www.dyndns.com, you should enter members.dyndns.org The dynamic DNS server port should normally be left at 80 (the default). You should set force updates Step 7: Configuring The ANALOG VARIABLES Fig.26: the Variables set-up page allows you to define and set up the various parameters (including minimum & maximum limits) for the four analog inputs. In this case, we have set up a temperature sensor on Variable 0. F IG.26 SHOWS the analog variables set-up page. This has fields for each of the four analog inputs (ie, Variable 0 to Variable 3). You only have to enter data for the sensors used. For example, if you have a temperature sensor connected to input AN0 (pin 9 of CON3), then you only have to enter data into the Variable 0 fields. Before going further though, we’ll make it easy for you. If you are using the AD22103 temperature sensor, enter a value of 0.11663409 into the Gradient field and -8.928571429 94  Silicon Chip into the Y-intercept field. It’s then just a matter of entering the number of decimal points, the minimum and maximum limits for email notification (see below), the logging period and the number of logging entries. Let’s look at all this in greater detail. The Raw Value is the digitised ADC (analog-to-digital converter) value. This value will be between 0 and 1023 (inclusive), as this is a 10bit conversion. Remember that the voltage range will be from 0V (GND) to 3.3V (ie, the 3.3V rail voltage). If the sensor has an output voltage to 1 and then enter the username and password to log into the account you created with your dynamic DNS provider. That completes the dynamic DNS set-up. You should now be able to use the hostname to browse the website on the memory card from anywhere on the Internet. In our case, we chose silchip.redirectme.net as the hostname, so the home page can now be accessed from the Internet by entering silchip.redirectme.net/ home.cgi in a browser and logging in. That’s easier to remember than using 165.221.92.134/home.cgi to access the WIB. range greater than this, you will need to add a voltage divider (consisting of two resistors) to bring the voltage fed to the WIB’s input back within the 0-3.3V range. This is then taken into account when “calibrating” the sensor by setting the gradient and y-intercept values in the WIB. From the raw value, the actual value of the input variable is calculated using the gradient and y-intercept values as follows: value = gradient x raw + y-intercept This means that, in order for readings to be accurate, you will need to enter the correct gradient and y-intercept values for the particular sensor being used (note: we are assuming that the sensor has a linear response). Let’s consider the AD22103 temperature sensor, for example. This can measure temperatures ranging from 0-100°C and its output is “ratio­ metric”. From the data sheet, its output voltage (Vo) is given by the formula: Vo = (Vs/3.3) x (0.25 + 0.028 x T) . . . (1) where Vs is the actual supply voltage to the sensor (slightly less that 3.3V because of the series 110Ω resistor) and T is the temperature (0-100°C). As stated, the raw value is the ADC value and is determined by the equation; raw = (Vo/Vdd) x 1023 . . . (2) where Vdd is the actual voltage of the 3.3V supply rail. Rearranging and plugging this into siliconchip.com.au equation 1 gives the temperature as a function of the raw value: T = (3.3 x Vdd)/(Vs x 1023 x 0.028) x raw – (0.25/0.028) or T = (0.1152073733 x Vdd/Vs) x raw - 8.928571429 In practice, Vs will be about 3.23V, while Vdd will be about 3.27V. Therefore, the correct values for the gradient and Y-intercept for this temperature sensor are: (1) Gradient = 0.11663409; and (2) Y-intercept = -8.928571429 These values must be entered in the Variable 0 gradient and Y-intercept fields respectively (assuming the sensor is connected to AN0). You can also enter in minimum and maximum limits for the sensor. When these limits are breached, an email is sent automatically. If the measured value drops below the minimum limit, the file var0min. txt appears in the email body. Conversely, if the maximum limit is exceeded, var0max.txt is included. For Variable #1, the corresponding files are var1min.txt and var1max. txt and so on. Note that a 10% limit value hys- teresis is included in the firmware to prevent too many emails from being sent in a short time, eg, if the temperature is fluctuating about a limit. You can also enter the name of the variable being monitored. For example, if you have a temperature sensor connected to Variable #0 (AN0), you can give it the name “Temperature”. This name will then be used in the log file and will also be referred to in any limit condition email messages. The Log Period field lets you enter a number that sets the logging interval in minutes (0 = logging off). The system adds to the log until the number of log entries reaches the number entered in “Set Log Size” field. At this point, the log file is automatically emailed to the specified email address and then cleared, ready for the next logging cycle. For example, suppose the Log Period is set to 10 minutes and the Log Size is set to 144. In this case, the input value will be logged every 10 minutes (along with the time of day) and after 144 such entries the whole log will be emailed and then cleared. As a result, an email containing the logged entries will be sent once every 24 hours. Similarly, setting the Log Period Step 8: CREATE THE NEW DEFAULTS T HIS FINAL STEP is short and sweet! Once you’ve made all the changes to the settings, go to the Basic page of the supplied website and click on the Create Defaults button. This will make your settings the new defaults and create a new set- tings.txt file with these new defaults. That completes the set-up of the WIB. Next month, we’ll describe the special system files that make up the website and also briefly describe how to design your own website with active content. to 10 minutes and the Log Size to 12 will result in the log being emailed every two hours. Finally, you can edit the text in the various “.txt” files to suit your application and the content is dynamic, ie, a number of variables can be included. When the email is sent, the system replaces these variables with the relevant information. For example, the content of var0­ max.txt is as follows: The ~1E is currently at ~D0 which is above the set maximum of ~1C! This is an automatically generated message, created on ~E2. In this case, 1E is the name of Variable #0 (“Temperature” in our case), D0 is the current value of Variable #0, 1C is the maximum limit set for Variable #0 and E2 is the current time. So, for example, the actual message that’s sent could be: The temperature is currently at 31.0 which is above the set maximum of 30.0! This is an automatically generated message, created on Fri 28 August 2009 17:00:00. We’ll describe this in greater detail next month and post a table listing the dynamic page content codes on our website. Network Addresses If your modem/router uses a 10.x.x.x private (ie, inwards facing) IP address, then you should change the IP address of the WIB to suit this network – eg, to 10.0.0.34 if the network is 10.0.0.x. That’s done by editing the settings.txt file on the memory card as described in Step 5. All other settings including the DHCP range, the Gateway address and the primary DNS address should also be changed accordingly. Accessing The WIB’s Website From The Internet Inside your home network, you can access the WIB home page simply by entering 192.168.0.34/home.cgi in the address field of your web browser and then logging in. Accessing the WIB’s website is just as easy from anywhere on the Internet. First, you can access it by using its public IP address; eg, 165.221.92.134/home.cgi Alternatively, if you’ve set up dynamic DNS siliconchip.com.au as described in Step 6, you will be able to access it by using the hostname defined in your dynamic DNS account. In our case, the hostname is silchip.redirectme.net and so we can access the WIB using the address silchip.redirectme.net/home.cgi Alternatively, you can go to another page (not necessarily in the root folder) by using a forward slash and the filename. For example, if we want to access a file named mydocument.doc in a sub-folder called documents, we enter silchip.redirectme. net/documents/mydocument.doc in the address field of the browser. Of course, this also works inside your local network, ie, we would enter 192.168.0.34/documents/mydocument. doc into the browser. Note that you can not access the WIB using the hostname SC from inside the network. December 2009  95