Hostap - WEP - Bridge problem?
Jeff Omick
jomick
Sat Apr 26 17:49:05 PDT 2003
Hi,
Not sure how to present this but I have been looking at this for
acouple of days now on and
off.
Configuration:
Wireless PC (kauai) ---- 802.11 w/Wep key ----- wlan0- Hostap
bridging-eth0 ----- Linux machine (Molokai)
I also replaced Kauai with a different pc and an imbedded wireless card
same fingerprint as below.
The issue is I cannot do a ftp from my wireless PC (kauai) to the Linux
machine (Molokai) and do a put
or i cannot FTP from molokai to the PC and do a get. (The FTP hangs -
packet get corrupted)
I think it has to do with buffer allocation or a MTU gets broken because
if I reduce the MTU the problem goes away.
If you notice the Packet size on the AP it is bigger than 1514 it is
1522 but only 96 gets captured.
And if you look at the packet traces (Attached below) the payload gets
truncated at the AP side.
The length of the ftp payload leaving kauai is 1448 bytes and the
payload on the AP side is only
30 bytes (Rest of packet is lost). Molokai never sees this packet on
it's ethereal capture.
This issue only occurs when I have the combination of WEP key,
Hostap(DWL-650), and Bridging.
This issue goes away if I do ANY of the following:
- I turn off WEP (iwconfig wlan0 enc off on ap and turn off wep security
on kauai)
- I remove bridging and do routing though the hostap machine.
- reduce my MTU (this is why I think it is overloading a buffer somewhere)
- use Hermes_ap (with Orinoco card of course)
I have to tell you that I think the work done here has been fabulous you
have put
together a great package and I love it.. I am getting by because I
lowered my MTU
and things work great in that mode, but I thought i would put out this
finding to help the
cause.
Software:
hostap-0.0.1.tar.gz
Redhat kernel - 2.4.20
pcmcia-cs-3.2.4.tar.gz
wireless_tools.25.tar.gz
Hardware:
Socket 0:
product info: "D", "Link DWL-650 11Mbps WLAN Card", "Version 01.02", ""
manfid: 0x0156, 0x0002
function: 6 (network)
Socket 1:
product info: "NETGEAR", "FA410TX", "Fast Ethernet"
manfid: 0x0149, 0x0230
function: 6 (network)
Gateway Solo 75Mhz Pentuim
[root at solo wlan]# iwconfig wlan0
wlan0 IEEE 802.11b ESSID:"OmsNet" Nickname:"solo"
Mode:Master Frequency:2.422GHz Access Point:
00:05:5D:EE:73:0F Bit Rate:2Mb/s Tx-Power:-1 dBm
Sensitivity=1/3 Retry min limit:8 RTS thr:off Fragment thr:off
Encryption key:3131-3131-31 Encryption mode:restricted
Power Management:off
Link Quality:0 Signal level:0 Noise level:0
Rx invalid nwid:0 Rx invalid crypt:838 Rx invalid frag:0
Tx excessive retries:915 Invalid misc:208 Missed beacon:0
Thanks for listening
Let me know if there is any other data you would like to see of have me
test
if you think it would help.
Jeff Omick
jomick at users.sourceforge.net
--------------------------------------------
Packet trace at Kauai side.
Frame 27 (1514 on wire, 1514 captured)
Arrival Time: Apr 25, 2003 19:00:38.125355000
Time delta from previous packet: 0.004764000 seconds
Time relative to first packet: 13.465361000 seconds
Frame Number: 27
Packet Length: 1514 bytes
Capture Length: 1514 bytes
Ethernet II
Destination: 00:04:5a:72:e0:62 (The_72:e0:62)
Source: 00:60:1d:04:78:54 (Lucent_04:78:54)
Type: IP (0x0800)
Internet Protocol, Src Addr: 192.168.0.14 (192.168.0.14), Dst Addr:
192.168.0.1 (192.168.0.1)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
0000 00.. = Differentiated Services Codepoint: Default (0x00)
.... ..0. = ECN-Capable Transport (ECT): 0
.... ...0 = ECN-CE: 0
Total Length: 1500
Identification: 0x2274
Flags: 0x04
.1.. = Don't fragment: Set
..0. = More fragments: Not set
Fragment offset: 0
Time to live: 128
Protocol: TCP (0x06)
Header checksum: 0x5148 (correct)
Source: 192.168.0.14 (192.168.0.14)
Destination: 192.168.0.1 (192.168.0.1)
Transmission Control Protocol, Src Port: 1059 (1059), Dst Port: ftp-data
(20), Seq: 3897295803, Ack: 3505752771
Source port: 1059 (1059)
Destination port: ftp-data (20)
Sequence number: 3897295803
Next sequence number: 3897297251
Acknowledgement number: 3505752771
Header length: 32 bytes
Flags: 0x0010 (ACK)
0... .... = Congestion Window Reduced (CWR): Not set
.0.. .... = ECN-Echo: Not set
..0. .... = Urgent: Not set
...1 .... = Acknowledgment: Set
.... 0... = Push: Not set
.... .0.. = Reset: Not set
.... ..0. = Syn: Not set
.... ...0 = Fin: Not set
Window size: 17520
Checksum: 0x5ee6 (correct)
Options: (12 bytes)
NOP
NOP
Time stamp: tsval 117138, tsecr 68369212
FTP Data
FTP Data: 6/14/2002\t6:06 PM\t\tAdministrator\tKAUAI\tExtracting Zip
file from stub file,
C:\DOCUME~1\ADMINI~1\LOCALS~1\TEMP\~SDAT4UP.tmp\DATS\cdex4207.exe.\r\r\n6/14/2002\t6:06
PM\t\tAdministrator\tKAUAI\tPerforming self validation ...\r\ (it goes
on when viewing raw data...)
( I Think the print statement of Ethereal did not correctly print the
data but if you look at ethereal
capture of the raw data you see the hole payload)
-------------------------------------------------------------
Trace of Packet on AP side.
Frame 43 (1522 on wire, 96 captured)
Arrival Time: Apr 25, 2003 17:58:48.306638000
Time delta from previous packet: 0.017794000 seconds
Time relative to first packet: 16.075410000 seconds
Frame Number: 43
Packet Length: 1522 bytes
Capture Length: 96 bytes
Ethernet II
Destination: 00:04:5a:72:e0:62 (The_72:e0:62)
Source: 00:60:1d:04:78:54 (Lucent_04:78:54)
Type: IP (0x0800)
Internet Protocol, Src Addr: 192.168.0.14 (192.168.0.14), Dst Addr:
192.168.0.1 (192.168.0.1)
Version: 4
Header length: 20 bytes
Differentiated Services Field: 0x00 (DSCP 0x00: Default; ECN: 0x00)
0000 00.. = Differentiated Services Codepoint: Default (0x00)
.... ..0. = ECN-Capable Transport (ECT): 0
.... ...0 = ECN-CE: 0
Total Length: 1500
Identification: 0x2274
Flags: 0x04
.1.. = Don't fragment: Set
..0. = More fragments: Not set
Fragment offset: 0
Time to live: 128
Protocol: TCP (0x06)
Header checksum: 0x5148 (correct)
Source: 192.168.0.14 (192.168.0.14)
Destination: 192.168.0.1 (192.168.0.1)
Transmission Control Protocol, Src Port: 1059 (1059), Dst Port: ftp-data
(20), Seq: 3897295803, Ack: 3505752771
Source port: 1059 (1059)
Destination port: ftp-data (20)
Sequence number: 3897295803
Next sequence number: 3897297251
Acknowledgement number: 3505752771
Header length: 32 bytes
Flags: 0x0010 (ACK)
0... .... = Congestion Window Reduced (CWR): Not set
.0.. .... = ECN-Echo: Not set
..0. .... = Urgent: Not set
...1 .... = Acknowledgment: Set
.... 0... = Push: Not set
.... .0.. = Reset: Not set
.... ..0. = Syn: Not set
.... ...0 = Fin: Not set
Window size: 17520
Checksum: 0x5ee6
Options: (12 bytes)
NOP
NOP
Time stamp: tsval 117138, tsecr 68369212
FTP Data
FTP Data: 6/14/2002\t6:06 PM\t\tAdministrat
(Notice the payload is cut off at 30 bytes - that is it looking at the
print format or raw format)
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