Setting Up a Cable Modem on SGI/IRIX: HOWTO

Setting Up a Cable Modem on SGI/IRIX: HOWTO

The world would be a better place if everyone wrote down what they know and put it on the Web. — Philip Greenspun

Please tell me how this procedure worked for you by sending e-mail to If you can add comments or a link to related information, then do so by clicking “Add a comment” or “Add a link” at the bottom of this page.
The Big Picture

You want to set up an IRIX box to use a cable modem, and your ISP dynamically assigns an IP address when you connect. This document explains how to configure an IRIX system to use a cable modem, and it is the procedure I used to connect my SGI O2, running IRIX 6.5, to RoadRunner’s cable service — my RoadRunner service does not require log in software. If your service requires log in software, see Sean Houghton’s Usenet posting.

* Things You Need Before You Begin
* Configure DHCP
* Set the Default Gateway and Name Servers
* Troubleshooting

Things You Need Before You Begin

* Root access on your IRIX box
* Means of accessing this procedure when you are offline (procedure requires a reboot before you complete the steps)
* Your ISP’s default gateway and the IP of its primary and secondary name server

To get this information, either call your ISP or connect to it with another system and get the information from that system. For example:

1. Connect your Win 9x system to the Internet using your cable modem
2. Click Start -> Run
3. Type: winipcfg, hit
4. Click “More Info”
5. Write down the primary and secondary DNS servers (click “…” to get the second one)
6. Write down the default gateway and netmask (shouldn’t need the netmask but just in case you do)

Configure DHCP

1. Connect the cable modem to your IRIX box with an ethernet cable (use a patch cable, not a cross-over cable)
2. Reset the modem by unplugging the power connector and plugging it back in
3. Log in to your IRIX box
4. Open a winterm and su to root:

coyote ~ 1% su –

5. Ensure that autoconfig_ipaddress is turned on:

coyote 1# /etc/chkconfig autoconfig_ipaddress on
coyote 2# /etc/chkconfig

Flag State
==== =====

autoconfig_ipaddress on

By setting autoconfig_ipaddress to on, you are telling your system to run proclaim at boot time. For more information on proclaim, read its man page by typing man proclaim at a prompt — here’s an excerpt:

Proclaim is a client that communicates with a DHCP server to obtain configuration parameters, including at least an IP address. The format of DHCP messages is based on the format of bootp messages, described in RFC 951. A detailed protocol specification of DHCP is in RFC 1541, available from the Network Information Center.

The DHCP protocol uses UDP/IP as its transport mechanism. The DHCP server receives service requests at the UDP port indicated in the bootp service description contained in the file /etc/services; see services(4).

Proclaim can be used to setup and configure new systems automatically, and to move systems from one net to another without administrative intervention. It can also be used to automatically verify current configurations at reboot. Only the superuser can employ proclaim. If the primary network interface is changed, proclaim updates the netaddr variable in the NVRAM.

In the absence of the DHCPoptionsToGet keyword, proclaim requests the following configuration parameters from an available DHCP server:
* an IP address
* the lease duration (3 year default)
* the subnet mask
* hostname (users may be allowed to choose their own)
* NIS domainname if the NIS option is installed.
* IP address of the DHCP server; see dhcp_bootp(1M).

As you can see, proclaim will automatically set the IP address, subnet mask, hostname, and IP address of the DHCP server. But, it does NOT set the default gateway or the name servers.

Set the Default Gateway and Name Servers
Beginning from Toolchest:

1. Click System -> System Manager -> Networking and Connectivity -> Set Up and Start Networking -> Next
2. Select the network interface to configure: Ensure that the interface connecting the cable modem is selected, click Next
3. Specify a hostname and IP address:
1. Ensure that Use DHCP Client is NOT checked (proclaim will handle this function)
2. Enter a hostname (ex: coyote) — proclaim will probably prepend it to your ISPs domain (ex:
3. Enter an arbitrary IP address and netmask (proclaim will set these at boot time, but this configurator requires that you enter something)
4. Click Next
4. Confirm your settings: Click OK
5. DO NOT restart your system

Back in the System Manger (window should still be open from earlier):

1. Click Modify Network Settings -> Next
2. Set the state of the primary network interface: Ensure that the primary network interface is enabled, click Next
3. Add a default route to the network routing table: Select “add default route”, and enter the IP address of your ISP’s default gateway, click Next
4. Disable (or enable) IP forwarding: this is up to you (I have mine disabled), click Next
5. Set DNS name server entries: Enter the IP for your ISP’s primary and secondary name servers, click Next
6. Specify host resolution order: Set it how you want it (mine is set as “Files”, “DNS”, “None”), click Next
7. Confirm your settings: Click Next
8. Reboot the system: As the system comes up, watch to see if the IP, hostname, and subnet mask are set and if any errors occur

When the system comes back up, you should be online. Open a terminal and ping
First, su to root.

* Reset your modem again (unplug it, plug it back in), and then run proclaim manually:

coyote 1# /usr/etc/proclaim
Configuring ec0 as coyote
add net default: gateway
Network daemons: portmap named.
Name services: nsd.
NFS daemons: nfsd biod.
Internet daemons: inetd timed.

* Check to see if you have been assigned and IP, the netmask is correct, and it says “UP:

coyote 2# /usr/etc/ifconfig ec0
ec0: flags=c43
inet netmask 0xfffffc00 broadcast

If it doesn’t say up, bring it up:

coyote 3# /usr/etc/ifconfig ec0 up

* Check the config files:

coyote 4# cat /var/adm/proclaim.lease_info_ascii.ec0

MessageType: 5
LeaseTimeInSecs: 86400
NetworkMask: 0xfffffc00

coyote 5# cat /etc/config/static-route.options

$ROUTE $QUIET add net default

* Check netstat

coyote /var/adm 6# netstat -rn
Routing tables

Destination Gateway Netmask Flags Refs Use Interface
default UGS 6 121 ec0
24.162.136 link#1 0xfffffc00 UC 0 0 ec0 UH 19 3 lo0
224 link#1 0xf0000000 UCS 0 0 ec0

coyote /var/adm 62# netstat -ian
Name Mtu Network Address Ipkts Ierrs Opkts Oerrs Coll
ec0 1500 24.162.136 59519 0 56688 0 5022
lo0 8304 127 29884 0 29884 0 0

* Manually add a default route (replace “GATEWAY_IP” with the actual IP of your ISP’s gateway):

coyote 7# /usr/etc/route add default GATEWAY_IP

Try pinging again. If it still doesn’t work…

* Consider flushing you network routing tables, and then add the default gateway again:

coyote 8# /usr/etc/route flush
coyote 9# /usr/etc/route add default GATEWAY_IP

Trying pinging again. If it still doesn’t work…

* Set the modem’s IP as the default route instead of the ISP’s gateway (replace HOST_IP_ADDRESS with the IP address from cat proclaim.lease_info_ascii.ec0:

NOTE: This does not work for me, but some others have suggested it.

coyote 10# /usr/etc/route add default HOST_IP_ADDRESS

If it still doesn’t work…

* Experiment or use to search the comp.sys.sgi.* archives.


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