RT2500 wifi card could not connect to wireless router using WPA personal.
OS - RHEL4; Dell Inspiron C600; interface detected ra0

Do you have wpasupplicant installed? (Most network managers use wpa_cli to negotiate the connection.)
Which method (application, scripts, etc.) are you using to (attempt to) connect? Have you configured the app correctly for your AP?
Have you seen any error messages? (Look in dmesg | tail and cat /var/log/wpa_supplicant.log.) What, if any, are those errors?

<edit>
Note: I don't use RHEL, so the above is a "generic" how-to-resolve-a-problem list of suggestions.
</edit>

i do have wpasupplicant installed. wpa_gui is not showing the ra0 interface. there is no /var/log/wpa_supplicant.log file created.

And . . . (I.e., there were three questions I asked.)

Your (attempted) access method is the most crucial. Describe (in extreme, step-by-step, detail) exactly what you do to attempt to get a connect. Be sure to give the name and version number of any application used for any step. (Note: If you're running from a GUI, look at the details of the menu entry (using your menu editor option) to find the application name. Almost all aplication versions can be found by entering the application name followed by --version in a terminal window.)

Can you show the contents of /etc/sysconfig/wpa_supplicant? Usually the default settings suffice, but you may have something in there that's interfering. Here's my (default) setting:You might also want to see if you have a /etc/wpa_supplicant.conf or /etc/wpa_supplicant/wpa_supplicant.conf file, and, if so, that the conf file contents are correct. (In most cases, you don't need a wpa_supplicant.conf file since the app.s will use wpa_cli to negotiate the connection.)

If you're device is running, iwconfig and ifconfig should look somewhat like this:If you're using wicd as your connection manager, make sure that the values in /etc/wicd/wireless_settings.conf are correct. (Note that your WPA key is displayed, unencrypted, in that file. That's why you need"root" permission to look at it.)

[root@localhost ~]# wpa_supplicant -v
wpa_supplicant v0.6.9
Copyright (c) 2003-2009, Jouni Malinen <j@w1.fi> and contributors
[root@localhost ~]# cat /etc/sysconfig/wpa_supplicant
cat: /etc/sysconfig/wpa_supplicant: No such file or directory
[root@localhost ~]# cat /etc/wpa_supplicant.conf
ctrl_interface=/var/run/wpa_supplicant
#ap_scan=2

network={
ssid="cebu"
scan_ssid=1
proto=WPA
pairwise=TKIP
group=TKIP
psk=d4e680b477ce3b71a6ea2dc0bc45b578971b0815888cf7e3cf9bb5eb4417aa26
}
[root@localhost ~]# wpa_supplicant -i ra0 -c/etc/wpa_supplicant.conf
ioctl[SIOCSIWENCODEEXT]: Operation not supported
ioctl[SIOCSIWENCODEEXT]: Operation not supported
ioctl[SIOCSIWENCODEEXT]: Operation not supported
ioctl[SIOCSIWENCODEEXT]: Operation not supported
CTRL-EVENT-SCAN-RESULTS
CTRL-EVENT-SCAN-RESULTS
CTRL-EVENT-SCAN-RESULTS
CTRL-EVENT-SCAN-RESULTS
CTRL-EVENT-SCAN-RESULTS
CTRL-EVENT-SCAN-RESULTS
CTRL-EVENT-SCAN-RESULTS
CTRL-EVENT-SCAN-RESULTS
CTRL-EVENT-SCAN-RESULTS
CTRL-EVENT-SCAN-RESULTS
CTRL-EVENT-SCAN-RESULTS
CTRL-EVENT-SCAN-RESULTS

[root@localhost ~]# iwconfig ra0
ra0 RT2500 Wireless ESSID:"cebu"
Mode:Managed Frequency=2.437GHz Bit Rate:11Mb/s
RTS thrff Fragment thrff
Encryption keyff
Link Quality=0/100 Signal level=-120 dBm Noise level:-192 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0

[root@localhost ~]# ifconfig ra0
ra0 Link encap:Ethernet HWaddr 00:0E:2E:5E:87:43
inet6 addr: fe80::20e:2eff:fe5e:8743/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:106904 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:4703748 (4.4 MiB)
Interrupt:11 Base address:0x8000

[root@localhost ~]#

[root@localhost ~]# wpa_supplicant -dd -c/etc/wpa_supplicant.conf -ira0
Initializing interface 'ra0' conf '/etc/wpa_supplicant.conf' driver 'default' ctrl_interface 'N/A' bridge 'N/A'
Configuration file '/etc/wpa_supplicant.conf' -> '/etc/wpa_supplicant.conf'
Reading configuration file '/etc/wpa_supplicant.conf'
ctrl_interface='/var/run/wpa_supplicant'
Line: 4 - start of a new network block
ssid - hexdump_ascii(len=4):
63 65 62 75 cebu
proto: 0x3
key_mgmt: 0x2
pairwise: 0x8
group: 0x8
PSK - hexdump(len=32): [REMOVED]
Priority group 0
id=0 ssid='cebu'
Initializing interface (2) 'ra0'
Interface ra0 set UP - waiting a second for the driver to complete initialization
SIOCGIWRANGE: too old (short) data - assuming WPA is not supported
WEXT: Operstate: linkmode=1, operstate=5
Own MAC address: 00:0e:2e:5e:87:43
wpa_driver_wext_set_wpa
Driver does not support WPA.
wpa_driver_wext_set_key: alg=0 key_idx=0 set_tx=0 seq_len=0 key_len=0
ioctl[SIOCSIWENCODEEXT]: Operation not supported
Driver did not support SIOCSIWENCODEEXT, trying SIOCSIWENCODE
wpa_driver_wext_set_key: alg=0 key_idx=1 set_tx=0 seq_len=0 key_len=0
ioctl[SIOCSIWENCODEEXT]: Operation not supported
Driver did not support SIOCSIWENCODEEXT, trying SIOCSIWENCODE
wpa_driver_wext_set_key: alg=0 key_idx=2 set_tx=0 seq_len=0 key_len=0
ioctl[SIOCSIWENCODEEXT]: Operation not supported
Driver did not support SIOCSIWENCODEEXT, trying SIOCSIWENCODE
wpa_driver_wext_set_key: alg=0 key_idx=3 set_tx=0 seq_len=0 key_len=0
ioctl[SIOCSIWENCODEEXT]: Operation not supported
Driver did not support SIOCSIWENCODEEXT, trying SIOCSIWENCODE
wpa_driver_wext_set_countermeasures
wpa_driver_wext_set_drop_unencrypted
RSN: flushing PMKID list in the driver
Setting scan request: 0 sec 100000 usec
EAPOL: SUPP_PAE entering state DISCONNECTED
EAPOL: KEY_RX entering state NO_KEY_RECEIVE
EAPOL: SUPP_BE entering state INITIALIZE
EAP: EAP entering state DISABLED
Added interface ra0
RTM_NEWLINK: operstate=0 ifi_flags=0x1043 ([UP][RUNNING])
RTM_NEWLINK, IFLA_IFNAME: Interface 'ra0' added
RTM_NEWLINK: operstate=0 ifi_flags=0x1043 ([UP][RUNNING])
RTM_NEWLINK, IFLA_IFNAME: Interface 'ra0' added
RTM_NEWLINK: operstate=0 ifi_flags=0x1043 ([UP][RUNNING])
RTM_NEWLINK, IFLA_IFNAME: Interface 'ra0' added
State: DISCONNECTED -> SCANNING
Starting AP scan (broadcast SSID)
Trying to get current scan results first without requesting a new scan to speed up initial association
Received 85 bytes of scan results (1 BSSes)
CTRL-EVENT-SCAN-RESULTS
Selecting BSS from priority group 0
Try to find WPA-enabled AP
0: 00:11:24:0b:ee:ad ssid='APPLE NETWORK' wpa_ie_len=0 rsn_ie_len=0 caps=0x11
skip - no WPA/RSN IE
Try to find non-WPA AP
0: 00:11:24:0b:ee:ad ssid='APPLE NETWORK' wpa_ie_len=0 rsn_ie_len=0 caps=0x11
skip - SSID mismatch
No suitable AP found.
Setting scan request: 0 sec 0 usec
Starting AP scan (broadcast SSID)
Scan requested (ret=0) - scan timeout 5 seconds
EAPOL: disable timer tick
Scan timeout - try to get results
Received 161 bytes of scan results (2 BSSes)
CTRL-EVENT-SCAN-RESULTS
Selecting BSS from priority group 0
Try to find WPA-enabled AP
0: 00:1e:e5:2e:f5:3f ssid='cebu' wpa_ie_len=0 rsn_ie_len=0 caps=0x11
skip - no WPA/RSN IE
1: 00:11:24:0b:ee:ad ssid='APPLE NETWORK' wpa_ie_len=0 rsn_ie_len=0 caps=0x11
skip - no WPA/RSN IE
Try to find non-WPA AP
0: 00:1e:e5:2e:f5:3f ssid='cebu' wpa_ie_len=0 rsn_ie_len=0 caps=0x11
skip - non-WPA network not allowed
1: 00:11:24:0b:ee:ad ssid='APPLE NETWORK' wpa_ie_len=0 rsn_ie_len=0 caps=0x11
skip - SSID mismatch
No suitable AP found.
Setting scan request: 5 sec 0 usec
Starting AP scan (broadcast SSID)
Scan requested (ret=0) - scan timeout 5 seconds
CTRL-EVENT-TERMINATING - signal 2 received
Removing interface ra0
State: SCANNING -> DISCONNECTED
wpa_driver_wext_set_operstate: operstate 0->0 (DORMANT)
WEXT: Operstate: linkmode=-1, operstate=5
No keys have been configured - skip key clearing
EAPOL: External notification - portEnabled=0
EAPOL: External notification - portValid=0
wpa_driver_wext_set_wpa
Failed to disable WPA in the driver.
wpa_driver_wext_set_drop_unencrypted
wpa_driver_wext_set_countermeasures
No keys have been configured - skip key clearing
Cancelling scan request
Cancelling authentication timeout
WEXT: Operstate: linkmode=0, operstate=6

looks like my driver installed on the RT2500 card does not support WPA.

Perhaps. But you haven't yet mentioned which driver you're using.

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I am using rt2500-1.1.0-b4. Any idea which driver version does support WPA?

Look at this WiKi. Note that any kernel after 2.6.24 should have included a RT2500 driver with WPA support. What kernel version are you using? (uname -r should tell you.)

If you're stuck with an older kernel, the WiKi can help you create a driver.

I actually try the driver posted at the wiki but no luck.

[root@localhost downloads]# uname -a
Linux localhost.localdomain 2.6.9-34.EL #1 Fri Feb 24 16:44:51 EST 2006 i686 i686 i386 GNU/Linux
[root@localhost downloads]# cd RutilTv0.18
[root@localhost RutilTv0.18]# ls
art configure.sh include lib README rutilt_helper.1
AUTHORS COPYING INSTALL Makefile rutilt.1 set_ip.sh
[root@localhost RutilTv0.18]# ./configure.sh
Requested 'gtk+-2.0 >= 2.6.0' but version of GTK+ is 2.4.13
Please install (or upgrade to) GTK+ 2.6.0, at least.
[root@localhost RutilTv0.18]#

I also try updating gtk+ but it fails for glib dependencies.

checking for BASE_DEPENDENCIES... configure: error: Package requirements (glib-2.0 >= 2.21.3 atk >= 1.13.0 pango >= 1.20 cairo >= 1.6) were not met:

Requested 'glib-2.0 >= 2.21.3' but version of GLib is 2.4.7