My iwconfig output says the interface is up, but firefox says "Can't find server....". Why would this be?

More detail: using Slackware 12.0 with Dell ipw3945 card.
Four packages must be downloaded: ieee80211, ipw3945 module, ipw3945 daemon, and ucode (as I learned from a previous informative post). There is a lengthy INSTALL text in the module download which I followed, with one confessed exception: I did not install the new ieee80211 package, because Slackware 12 already has one, and it requires a kernel rebuild which I would not understand fully how to do. This could be damaging, but the computer did not seem to be having any problem. Here were some outputs.

IWCONFIG OUTPUT:

/home/z# iwconfig
lo no wireless extensions.

eth0 no wireless extensions.

eth1 IEEE 802.11g ESSID:"SCCL2_NONFICTION-G" Nickname:"juba5"
Mode:Managed Frequency:2.462 GHz Access Point: 00:0C:41:17:27:2B
Bit Rate:54 Mb/s Tx-Power:14 dBm
Retry limit:15 RTS thr:off Fragment thr:off
Encryption key:DEAD-BEEF-00 Security mode:open
Power Management:off
Link Quality=88/100 Signal level=-46 dBm Noise level=-47 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:21 Missed beacon:0

IFCONFIG OUTPUT:

/home/z# ifconfig
eth1 Link encap:Ethernet HWaddr 00:1B:77:68:50:97
inet6 addr: fe80::21b:77ff:fe68:5097/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1374 errors:13 dropped:39 overruns:0 frame:0
TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:156877 (153.2 KiB) TX bytes:478 (478.0 b)
Interrupt:18 Memory:fe8ff000-fe8fffff

THE LAST PART OF DMESG OUTPUT:

ieee80211_crypt: registered algorithm 'NULL'
ieee80211: 802.11 data/management/control stack, git-1.1.13
ieee80211: Copyright (C) 2004-2005 Intel Corporation <jketreno@linux.intel.com>
ipw3945: Intel(R) PRO/Wireless 3945 Network Connection driver for Linux, 1.2.2d
ipw3945: Copyright(c) 2003-2006 Intel Corporation
ACPI: PCI Interrupt 0000:0c:00.0[A] -> GSI 17 (level, low) -> IRQ 18
PCI: Setting latency timer of device 0000:0c:00.0 to 64
ipw3945: Detected Intel PRO/Wireless 3945ABG Network Connection
ipw3945: Detected geography ABG (11 802.11bg channels, 13 802.11a channels)
ADDRCONF(NETDEV_UP): eth1: link is not ready
ADDRCONF(NETDEV_CHANGE): eth1: link becomes ready
eth1: no IPv6 routers present
ieee80211_crypt: registered algorithm 'WEP'
/home/z#

The iwconfig output, particularly, seems to match the aforementioned INSTALL instructions, which said that at that point "you are there". But why can firefox not find any URL pages?

This usually happens when you don't have a default gateway set or are using a static IP address without entering the DNS server info.

man route will give you an example of the gateway setting. For me, it's:
# route add default gw 192.168.1.1

For DNS, enter your ISP's servers in /etc/resolv.conf. Example:
search oc.cox.net
nameserver 68.105.28.12
nameserver 68.105.29.12
nameserver 68.105.28.11

Thanks, 2Gnu. You were correct that I have no default gateway. I have been wrestling here at the library trying to find one, but cannot complete the route command satisfactorily.

Here again is a sample of my configurations, including one with eth0.

/home/z/ipw3945-1.2.2# ifconfig
eth0 Link encap:Ethernet HWaddr 00:1A:A0:FB:FC:A8
inet addr:192.168.2.111 Bcast:192.168.2.255 Mask:255.255.255.0
inet6 addr: fe80::21a:a0ff:fefb:fca8/64 Scope:Link
UP BROADCAST NOTRAILERS RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:3 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:270 (270.0 b)
Interrupt:18

eth1 Link encap:Ethernet HWaddr 00:1B:77:68:50:97
inet6 addr: fe80::21b:77ff:fe68:5097/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:5 errors:0 dropped:21 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1112 (1.0 KiB) TX bytes:490 (490.0 b)
Interrupt:18 Base address:0x8000 Memory:fe8ff000-fe8fffff

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)

/home/z/ipw3945-1.2.2# iwconfig
lo no wireless extensions.

eth0 no wireless extensions.

eth1 IEEE 802.11g ESSID:"SCCL" Nickname:"juba5"
Mode:Managed Frequency:2.412 GHz Access Point: 00:1A:E31:E7:11
Bit Rate:54 Mb/s Tx-Power:15 dBm
Retry limit:15 RTS thrff Fragment thrff
Encryption keyff
Power Managementff
Link Quality=89/100 Signal level=-43 dBm Noise level=-44 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:26 Missed beacon:0

When I bring up the computer with the ethernet jack connected, the routing table has a default gateway address in it, in addition to the loopback address, and the browser finds pages. When I bring it up without ethernet and then load ipw3945, eth1 is there as you see, but there is no default gateway, even if I have started routed, which is supposed to do these things automatically, according to "Running Linux (1999 ed.)". Also there is no "inet addr" for eth1, as seen above. I tried the route command with two IP address guesses: the one eth0 had been given, and one the girl at the library gave me. In both cases, the reply from "route" was "SIOCADDRT: No such process".

"Running Linux" says the network administrator is supposed to supply this gateway address. The girl told me, though, that only a few Mac users ever had any trouble. Do you have any suggestions on this point?

I did not know you were using a library wireless.

Don't use the wired interface.

Take the wired NIC down with #ifconfig eth0 down

Bring up the wireless NIC with ifconfig eth1 up

Set the ESSID with iwconfig eth1 essid SCCL

Obtain an IP address with dhcpcd eth1

That should set the gateway and pull DNS server info.

Thanks very much, 2Gnu. My wireless connections is working.

For your records, the ESSID setting did not seem to be necessary; ifconfig appeared to have gotten an ESSID. The dhcpcd was the vital one. The complete set of steps were as follows. 1. "load", using the downloaded script to start the ipw3945d daemon. 2. ifconfig eth1 up 3. dhcpcd eth1. 4. The browser works.
What is baffling is that this connection is much like the ethernet connection in principle and in fact in several steps, but seems to have a couple of key differences.

With much appreciation, dafydil.