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The Internet has become the number one platform for network communications worldwide. As true network system, Linux can handle a broad range of Internet related tasks — both as a server and as a client system. This chapter discusses some of the topics relevant to the Internet: the configuration of the smpppd (the SUSE Meta PPP Daemon), the manual configuration of ADSL access, and the configuration of the Squid proxy.
Most home users do not have a dedicated line connecting them to the Internet. Rather, they use dial-up connections. Depending on the dial-up method (ISDN or DSL), the connection is controlled by the ipppd or the pppd. Basically, all that needs to be done to go online is to start these programs correctly.
If you have a flat-rate connection that does not generate any additional costs for the dial-up connection, simply start the respective daemon. Control the dial-up connection with a KDE applet or a command-line interface. If the Internet gateway is not the host you are using, you might want to control the dial-up connection by way of a network host.
This is where smpppd is involved. It provides a uniform interface for auxiliary programs and acts in two directions: first, it programs the required pppd or ipppd and controls its dial-up properties. Second, it makes various providers available to the user programs and transmits information about the current status of the connection. As smpppd can also be controlled by way of the network, it is suitable for controlling dial-up connections to the Internet from a workstation in a private subnetwork.
The connections provided by smpppd are automatically configured by YaST. The actual dial-up programs kinternet and cinternet are also preconfigured. Manual settings are only required to configure additional features of smpppd, such as remote control.
The configuration file of smpppd is /etc/smpppd.conf. By default, it does not enable remote control. The most important options of this configuration file are as follows:
To control smpppd via the network, this option must be set to yes. The port on which the smpppd listens is 3185. If this parameter is set to yes, the parameters bind-address, host-range, and password should also be set accordingly.
If a host has several IP addresses, this parameter can be used to determine by which IP address smpppd should accept connections.
The parameter host-range can be used to define a network range. Hosts whose IP addresses are within this range are granted access to smpppd. All hosts not within this range are denied access.
By assigning a password, limit the clients to authorized hosts. As this is a plain-text password, you should not overrate the security it provides. If no password is assigned, all clients are entitled to access smpppd.
More information about smpppd is available in man 8 smpppd and man 5 smpppd.conf.
The programs kinternet and cinternet can be used locally as well as for controlling a remote smpppd. cinternet is the the command-line counterpart of the graphical kinternet. To prepare these utilities for use with a remote smpppd, edit the configuration file /etc/smpppd-c.conf manually or using kinternet. This file only uses three options:
Here, specify the host on which smpppd runs. If this host is the same as the default gateway of the host, it is sufficient to set the gateway-fallback to yes.
If no server was specified and there is no local smpppd, this option, which is enabled by default, causes a search for an smpppd on the default gateway.
Insert the password selected for smpppd.
If the smpppd is active, you can now try to access it. This can be done with the command cinternet --verbose --interface-list. If you experience difficulties at this point, refer to man 5 smpppd-c.conf and man 8 cinternet