Internet Services system configuration limitations

Morningstar PPP dial-in connections

PPP dial-in connections sometimes fail during initialization; this produces the following error message in /usr/adm/pppd.log:

   pppd: Fatal system error: Can't ifconfig du1 (SIOCSIFADDR): File exists

Repeating the dial-in attempt should be successful.

Path maximal transmittal unit (MTU) Discovery disabled

Your SCO OpenServer system is initially configured with the following two kernel parameters set to 0: tcp_offer_big_mss and ip_perform_pmtu. This disables the ``Path MTU Discovery,'' as defined in RFC 1191. Path MTU Discovery allows your system to determine the MTU size to use while communicating with another system, in order to avoid IP datagram fragmentation and increase throughput.

There is some router equipment on the Internet that does not generate proper responses when an MTU size needs to be adjusted; this may cause connections to hang. For this reason, SCO has disabled this feature for this release.

If you wish to enable this feature, enter the following commands as root:

/etc/inconfig tcp_offer_big_mss 1
/etc/inconfig ip_perform_pmtu 1

Internet Manager remote administration

If you wish to remotely administer your SCO OpenServer system from a machine whose web browser is configured to use a proxy server, you must put the IP address of that proxy server into the remote access list of the Internet Manager.

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WARNING: This will enable any user who is using the same proxy server to administer your system if they have the correct password.

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Multiple machine names

If your machine has multiple names, such as when more than one networking interface is configured and each IP address has its own name, sendmail must be configured to accept mail for all of those names. To do this, run mkdev cf and add all the hostnames to the ``Alternate Host Names'' section. See ``Running mkdev cf'' for more information.