OpenVPN Support Forum

Hi. I've been struggling to set up OpenVPN, scanned the FAQ repeatedly, Googled for 3 days, but can't solve this.

Server: Windows Vista SP1, a single TAP-Win32 device, bridged
Two Clients: Windows XP and Windows 7 (on the same remote network, connecting over the Net, never concurrently)

The WinXP client connects, exchanges credentials (apparently successfully, despite some Authentication/Decrypt errors later), and acquires an Ipv4 subnet assignment from the server; but neither server nor client can Ping each other, and there is no usable connectivity that I can discover -- even though the server/client OpenVPN windows seem to be reading and writing to each other, and they mutually recognize disconnects instantly.

The Win7 client connects and both server and client can Ping, RDP, etc. In short, the Win7 client works fine. But oddly, Pings ("PING MACHINENAME" or "PING fe80::806:90d2:f01a:388a%26") only return Ipv6 addresses; remote Ipv4 addresses ("PING 10.8.0.2") time out. If I disable Ipv6 entirely on both server and Win7 client, I get the same failure on the Win7 client as on the WinXP client: no ping and no connectivity. It's almost as if OpenVPN is requiring a full Vista/Win7 Ipv6 stack.

So one client works, the other doesn't. The configs for them are identical (apart from different CERTs and KEYs, separately generated with easy-rsa). I don't see any config errors except an occasional "FlushIpNetTable failed on interface ... Element not found" on server & both clients (and Authentication/Decrypt errors, which are what? lost packets?). Routing on the server is identical after either client tries to connect (apart from different assigned remote addresses). Routing on the clients differs a bit. One difference is that WinXP reports no Ipv6 routes, only Ipv4 routes.
Another difference is:
Win 7 client 10.8.0.3 255.255.255.255 10.8.0.3
WinXP client 10.8.0.2 255.255.255.255 127.0.0.1
which suggests that WinXP is dying in the loopback interface... But my routing knowledge is nearly nil.

Can anybody suggest what might be wrong? I'm surely an idiot, but I haven't much hair left! Many thanks.

Vista Server:
port 1194
proto udp
dev tap
ca "F:\\OpenVPN\\easy-rsa\\keys\\ca.crt"
cert "F:\\OpenVPN\\easy-rsa\\keys\\server.crt"
key "F:\\OpenVPN\\easy-rsa\\keys\\server.key"
dh "F:\\OpenVPN\\easy-rsa\\keys\\dh1024.pem"
server-bridge 10.8.0.1 255.255.255.0 10.8.0.2 10.8.0.20
keepalive 10 120
comp-lzo
persist-key
persist-tun
status openvpn-status.log
verb 3
mute 20

Clients:
client
dev tap
proto udp
remote x.x.x.144 1194
resolv-retry infinite
nobind
persist-key
persist-tun
mute-replay-warnings
ca "L:\\OpenVPN\\easy-rsa\\keys\\ca.crt"
cert "L:\\OpenVPN\\easy-rsa\\keys\\HP.crt"
key "L:\\OpenVPN\\easy-rsa\\keys\\HP.key"
ns-cert-type server
comp-lzo
verb 6
mute 20

Server Log:
Sat Mar 05 19:06:21 2011 OpenVPN 2.1.4 i686-pc-mingw32 [SSL] [LZO2] [PKCS11] built on Nov 8 2010
Sat Mar 05 19:06:21 2011 NOTE: when bridging your LAN adapter with the TAP adapter, note that the new bridge adapter will often take on its own IP address that is different from what the LAN adapter was previously set to
Sat Mar 05 19:06:21 2011 NOTE: your local LAN uses the extremely common subnet address 192.168.0.x or 192.168.1.x. Be aware that this might create routing conflicts if you connect to the VPN server from public locations such as internet cafes that use the same subnet.
Sat Mar 05 19:06:21 2011 NOTE: the current --script-security setting may allow this configuration to call user-defined scripts
Sat Mar 05 19:06:21 2011 Diffie-Hellman initialized with 1024 bit key
Sat Mar 05 19:06:21 2011 TLS-Auth MTU parms [ L:1574 D:138 EF:38 EB:0 ET:0 EL:0 ]
Sat Mar 05 19:06:21 2011 Socket Buffers: R=[8192->8192] S=[8192->8192]
Sat Mar 05 19:06:21 2011 TAP-WIN32 device [Local Area Connection 4] opened: \\.\Global\{9558F5ED-365A-425E-AA2F-3F4CD5DDA1BF}.tap
Sat Mar 05 19:06:21 2011 TAP-Win32 Driver Version 9.7
Sat Mar 05 19:06:21 2011 TAP-Win32 MTU=1500
Sat Mar 05 19:06:21 2011 Sleeping for 10 seconds...
Sat Mar 05 19:06:31 2011 NOTE: FlushIpNetTable failed on interface [27] {9558F5ED-365A-425E-AA2F-3F4CD5DDA1BF} (status=1168) : Element not found.
Sat Mar 05 19:06:31 2011 Data Channel MTU parms [ L:1574 D:1450 EF:42 EB:135 ET:32 EL:0 AF:3/1 ]
Sat Mar 05 19:06:31 2011 UDPv4 link local (bound): [undef]:1194
Sat Mar 05 19:06:31 2011 UDPv4 link remote: [undef]
Sat Mar 05 19:06:31 2011 MULTI: multi_init called, r=256 v=256
Sat Mar 05 19:06:31 2011 IFCONFIG POOL: base=10.8.0.2 size=19
Sat Mar 05 19:06:31 2011 Initialization Sequence Completed
Sat Mar 05 19:11:06 2011 MULTI: multi_create_instance called
Sat Mar 05 19:11:06 2011 x.x.x.15:1197 Re-using SSL/TLS context
Sat Mar 05 19:11:06 2011 x.x.x.15:1197 LZO compression initialized
Sat Mar 05 19:11:06 2011 x.x.x.15:1197 Control Channel MTU parms [ L:1574 D:138 EF:38 EB:0 ET:0 EL:0 ]
Sat Mar 05 19:11:06 2011 x.x.x.15:1197 Data Channel MTU parms [ L:1574 D:1450 EF:42 EB:135 ET:32 EL:0 AF:3/1 ]
Sat Mar 05 19:11:06 2011 x.x.x.15:1197 Local Options hash (VER=V4): 'f7df56b8'
Sat Mar 05 19:11:06 2011 x.x.x.15:1197 Expected Remote Options hash (VER=V4): 'd79ca330'
Sat Mar 05 19:11:06 2011 x.x.x.15:1197 TLS: Initial packet from x.x.x.15:1197, sid=cf9ba423 302aff74
Sat Mar 05 19:11:07 2011 x.x.x.15:1197 VERIFY OK: depth=1, /C=US/ST=NY/L=NewYork/O=OpenVPN/CN=OpenVPN-NY/emailAddress=xxxxxx@xxxxxx.xxx
Sat Mar 05 19:11:07 2011 x.x.x.15:1197 VERIFY OK: depth=0, /C=US/ST=NY/O=OpenVPN/CN=T41P/emailAddress=xxxxxx@xxxxxx.xxx
Sat Mar 05 19:11:07 2011 x.x.x.15:1197 Data Channel Encrypt: Cipher 'BF-CBC' initialized with 128 bit key
Sat Mar 05 19:11:07 2011 x.x.x.15:1197 Data Channel Encrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Sat Mar 05 19:11:07 2011 x.x.x.15:1197 Data Channel Decrypt: Cipher 'BF-CBC' initialized with 128 bit key
Sat Mar 05 19:11:07 2011 x.x.x.15:1197 Data Channel Decrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Sat Mar 05 19:11:07 2011 x.x.x.15:1197 Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-AES256-SHA, 1024 bit RSA
Sat Mar 05 19:11:07 2011 x.x.x.15:1197 [T41P] Peer Connection Initiated with x.x.x.15:1197
Sat Mar 05 19:11:10 2011 T41P/x.x.x.15:1197 PUSH: Received control message: 'PUSH_REQUEST'
Sat Mar 05 19:11:10 2011 T41P/x.x.x.15:1197 SENT CONTROL [T41P]: 'PUSH_REPLY,route-gateway 10.8.0.1,ping 10,ping-restart 120,ifconfig 10.8.0.2 255.255.255.0' (status=1)
Sat Mar 05 19:11:10 2011 T41P/x.x.x.15:1197 MULTI: Learn: 00:ff:70:33:20:f7 -> T41P/x.x.x.15:1197

WinXP Client Log:
Sat Mar 05 19:11:06 2011 us=589000 Current Parameter Settings:
Sat Mar 05 19:11:06 2011 us=589000 config = 'L:\OpenVPN\config\T41P.ovpn'
Sat Mar 05 19:11:06 2011 us=589000 mode = 0
Sat Mar 05 19:11:06 2011 us=589000 show_ciphers = DISABLED
Sat Mar 05 19:11:06 2011 us=589000 show_digests = DISABLED
Sat Mar 05 19:11:06 2011 us=589000 show_engines = DISABLED
Sat Mar 05 19:11:06 2011 us=589000 genkey = DISABLED
Sat Mar 05 19:11:06 2011 us=589000 key_pass_file = '[UNDEF]'
Sat Mar 05 19:11:06 2011 us=589000 show_tls_ciphers = DISABLED
Sat Mar 05 19:11:06 2011 us=589000 Connection profiles [default]:
Sat Mar 05 19:11:06 2011 us=589000 proto = udp
Sat Mar 05 19:11:06 2011 us=589000 local = '[UNDEF]'
Sat Mar 05 19:11:06 2011 us=589000 local_port = 0
Sat Mar 05 19:11:06 2011 us=589000 remote = 'x.x.x.144'
Sat Mar 05 19:11:06 2011 us=589000 remote_port = 1194
Sat Mar 05 19:11:06 2011 us=589000 remote_float = DISABLED
Sat Mar 05 19:11:06 2011 us=589000 bind_defined = DISABLED
Sat Mar 05 19:11:06 2011 us=589000 bind_local = DISABLED
Sat Mar 05 19:11:06 2011 us=589000 connect_retry_seconds = 5
Sat Mar 05 19:11:06 2011 us=589000 connect_timeout = 10
Sat Mar 05 19:11:06 2011 us=589000 NOTE: --mute triggered...
Sat Mar 05 19:11:06 2011 us=589000 252 variation(s) on previous 20 message(s) suppressed by --mute
Sat Mar 05 19:11:06 2011 us=589000 OpenVPN 2.1.4 i686-pc-mingw32 [SSL] [LZO2] [PKCS11] built on Nov 8 2010
Sat Mar 05 19:11:06 2011 us=599000 NOTE: OpenVPN 2.1 requires '--script-security 2' or higher to call user-defined scripts or executables
Sat Mar 05 19:11:06 2011 us=749000 LZO compression initialized
Sat Mar 05 19:11:06 2011 us=749000 Control Channel MTU parms [ L:1574 D:138 EF:38 EB:0 ET:0 EL:0 ]
Sat Mar 05 19:11:06 2011 us=759000 Socket Buffers: R=[8192->8192] S=[8192->8192]
Sat Mar 05 19:11:06 2011 us=759000 Data Channel MTU parms [ L:1574 D:1450 EF:42 EB:135 ET:32 EL:0 AF:3/1 ]
Sat Mar 05 19:11:06 2011 us=759000 Local Options String: 'V4,dev-type tap,link-mtu 1574,tun-mtu 1532,proto UDPv4,comp-lzo,cipher BF-CBC,auth SHA1,keysize 128,key-method 2,tls-client'
Sat Mar 05 19:11:06 2011 us=759000 Expected Remote Options String: 'V4,dev-type tap,link-mtu 1574,tun-mtu 1532,proto UDPv4,comp-lzo,cipher BF-CBC,auth SHA1,keysize 128,key-method 2,tls-server'
Sat Mar 05 19:11:06 2011 us=759000 Local Options hash (VER=V4): 'd79ca330'
Sat Mar 05 19:11:06 2011 us=759000 Expected Remote Options hash (VER=V4): 'f7df56b8'
Sat Mar 05 19:11:06 2011 us=759000 UDPv4 link local: [undef]
Sat Mar 05 19:11:06 2011 us=759000 UDPv4 link remote: x.x.x.144:1194
Sat Mar 05 19:11:06 2011 us=759000 UDPv4 WRITE [14] to x.x.x.144:1194: P_CONTROL_HARD_RESET_CLIENT_V2 kid=0 [ ] pid=0 DATA len=0
Sat Mar 05 19:11:06 2011 us=759000 UDPv4 READ [0] from [undef]: DATA UNDEF len=-1
Sat Mar 05 19:11:06 2011 us=859000 UDPv4 READ [26] from x.x.x.144:1194: P_CONTROL_HARD_RESET_SERVER_V2 kid=0 [ 0 ] pid=0 DATA len=0
Sat Mar 05 19:11:06 2011 us=859000 TLS: Initial packet from x.x.x.144:1194, sid=584eed01 88baaf0f
Sat Mar 05 19:11:06 2011 us=859000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 0 ]
Sat Mar 05 19:11:06 2011 us=859000 UDPv4 WRITE [108] to x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=1 DATA len=94
Sat Mar 05 19:11:07 2011 us=29000 UDPv4 READ [126] from x.x.x.144:1194: P_CONTROL_V1 kid=0 [ 1 ] pid=1 DATA len=100
Sat Mar 05 19:11:07 2011 us=29000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 1 ]
Sat Mar 05 19:11:07 2011 us=29000 UDPv4 READ [114] from x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=2 DATA len=100
Sat Mar 05 19:11:07 2011 us=29000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 2 ]
Sat Mar 05 19:11:07 2011 us=29000 UDPv4 READ [114] from x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=3 DATA len=100
Sat Mar 05 19:11:07 2011 us=29000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 3 ]
Sat Mar 05 19:11:07 2011 us=39000 UDPv4 READ [114] from x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=4 DATA len=100
Sat Mar 05 19:11:07 2011 us=39000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 4 ]
Sat Mar 05 19:11:07 2011 us=119000 UDPv4 READ [114] from x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=5 DATA len=100
Sat Mar 05 19:11:07 2011 us=119000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 5 ]
Sat Mar 05 19:11:07 2011 us=119000 UDPv4 READ [114] from x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=6 DATA len=100
Sat Mar 05 19:11:07 2011 us=129000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 6 ]
Sat Mar 05 19:11:07 2011 us=139000 UDPv4 READ [114] from x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=7 DATA len=100
Sat Mar 05 19:11:07 2011 us=139000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 7 ]
Sat Mar 05 19:11:07 2011 us=139000 UDPv4 READ [114] from x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=8 DATA len=100
Sat Mar 05 19:11:07 2011 us=139000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 8 ]
Sat Mar 05 19:11:07 2011 us=209000 UDPv4 READ [114] from x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=9 DATA len=100
Sat Mar 05 19:11:07 2011 us=209000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 9 ]
Sat Mar 05 19:11:07 2011 us=219000 NOTE: --mute triggered...
Sat Mar 05 19:11:07 2011 us=400000 17 variation(s) on previous 20 message(s) suppressed by --mute
Sat Mar 05 19:11:07 2011 us=400000 VERIFY OK: depth=1, /C=US/ST=NY/L=NewYork/O=OpenVPN/CN=OpenVPN-NY/emailAddress=xxxxxx@xxxxxx.xxx
Sat Mar 05 19:11:07 2011 us=400000 VERIFY OK: nsCertType=SERVER
Sat Mar 05 19:11:07 2011 us=400000 VERIFY OK: depth=0, /C=US/ST=NY/O=OpenVPN/CN=server/emailAddress=xxxxxx@xxxxxx.xxx
Sat Mar 05 19:11:07 2011 us=400000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 18 ]
Sat Mar 05 19:11:07 2011 us=400000 UDPv4 READ [114] from x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=19 DATA len=100
Sat Mar 05 19:11:07 2011 us=400000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 19 ]
Sat Mar 05 19:11:07 2011 us=400000 UDPv4 READ [114] from x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=20 DATA len=100
Sat Mar 05 19:11:07 2011 us=400000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 20 ]
Sat Mar 05 19:11:07 2011 us=470000 UDPv4 READ [114] from x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=21 DATA len=100
Sat Mar 05 19:11:07 2011 us=470000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 21 ]
Sat Mar 05 19:11:07 2011 us=490000 UDPv4 READ [114] from x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=22 DATA len=100
Sat Mar 05 19:11:07 2011 us=490000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 22 ]
Sat Mar 05 19:11:07 2011 us=490000 UDPv4 READ [114] from x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=23 DATA len=100
Sat Mar 05 19:11:07 2011 us=490000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 23 ]
Sat Mar 05 19:11:07 2011 us=490000 UDPv4 READ [53] from x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=24 DATA len=39
Sat Mar 05 19:11:07 2011 us=720000 UDPv4 WRITE [126] to x.x.x.144:1194: P_CONTROL_V1 kid=0 [ 24 ] pid=2 DATA len=100
Sat Mar 05 19:11:07 2011 us=730000 UDPv4 WRITE [114] to x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=3 DATA len=100
Sat Mar 05 19:11:07 2011 us=730000 UDPv4 WRITE [114] to x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=4 DATA len=100
Sat Mar 05 19:11:07 2011 us=730000 UDPv4 WRITE [114] to x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=5 DATA len=100
Sat Mar 05 19:11:07 2011 us=830000 UDPv4 READ [22] from x.x.x.144:1194: P_ACK_V1 kid=0 [ 2 ]
Sat Mar 05 19:11:07 2011 us=830000 UDPv4 WRITE [114] to x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=6 DATA len=100
Sat Mar 05 19:11:07 2011 us=830000 UDPv4 READ [22] from x.x.x.144:1194: P_ACK_V1 kid=0 [ 3 ]
Sat Mar 05 19:11:07 2011 us=830000 UDPv4 WRITE [114] to x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=7 DATA len=100
Sat Mar 05 19:11:07 2011 us=840000 NOTE: --mute triggered...
Sat Mar 05 19:11:08 2011 us=381000 66 variation(s) on previous 20 message(s) suppressed by --mute
Sat Mar 05 19:11:08 2011 us=381000 Data Channel Encrypt: Cipher 'BF-CBC' initialized with 128 bit key
Sat Mar 05 19:11:08 2011 us=381000 Data Channel Encrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Sat Mar 05 19:11:08 2011 us=381000 Data Channel Decrypt: Cipher 'BF-CBC' initialized with 128 bit key
Sat Mar 05 19:11:08 2011 us=381000 Data Channel Decrypt: Using 160 bit message hash 'SHA1' for HMAC authentication
Sat Mar 05 19:11:08 2011 us=381000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 38 ]
Sat Mar 05 19:11:08 2011 us=381000 Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-AES256-SHA, 1024 bit RSA
Sat Mar 05 19:11:08 2011 us=381000 [server] Peer Connection Initiated with x.x.x.144:1194
Sat Mar 05 19:11:09 2011 us=603000 UDPv4 READ [93] from x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=92
Sat Mar 05 19:11:10 2011 us=614000 SENT CONTROL [server]: 'PUSH_REQUEST' (status=1)
Sat Mar 05 19:11:10 2011 us=614000 UDPv4 WRITE [104] to x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=27 DATA len=90
Sat Mar 05 19:11:10 2011 us=664000 UDPv4 READ [22] from x.x.x.144:1194: P_ACK_V1 kid=0 [ 27 ]
Sat Mar 05 19:11:10 2011 us=674000 UDPv4 READ [114] from x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=39 DATA len=100
Sat Mar 05 19:11:10 2011 us=674000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 39 ]
Sat Mar 05 19:11:10 2011 us=674000 UDPv4 READ [68] from x.x.x.144:1194: P_CONTROL_V1 kid=0 [ ] pid=40 DATA len=54
Sat Mar 05 19:11:10 2011 us=674000 PUSH: Received control message: 'PUSH_REPLY,route-gateway 10.8.0.1,ping 10,ping-restart 120,ifconfig 10.8.0.2 255.255.255.0'
Sat Mar 05 19:11:10 2011 us=674000 OPTIONS IMPORT: timers and/or timeouts modified
Sat Mar 05 19:11:10 2011 us=674000 OPTIONS IMPORT: --ifconfig/up options modified
Sat Mar 05 19:11:10 2011 us=674000 OPTIONS IMPORT: route-related options modified
Sat Mar 05 19:11:10 2011 us=704000 TAP-WIN32 device [Local Area Connection 5] opened: \\.\Global\{703320F7-4F13-45B6-B8AB-2E5D9A1A512E}.tap
Sat Mar 05 19:11:10 2011 us=704000 TAP-Win32 Driver Version 9.7
Sat Mar 05 19:11:10 2011 us=704000 TAP-Win32 MTU=1500
Sat Mar 05 19:11:10 2011 us=704000 Notified TAP-Win32 driver to set a DHCP IP/netmask of 10.8.0.2/255.255.255.0 on interface {703320F7-4F13-45B6-B8AB-2E5D9A1A512E} [DHCP-serv: 10.8.0.0, lease-time: 31536000]
Sat Mar 05 19:11:10 2011 us=704000 Successful ARP Flush on interface [4] {703320F7-4F13-45B6-B8AB-2E5D9A1A512E}
Sat Mar 05 19:11:10 2011 us=724000 UDPv4 WRITE [22] to x.x.x.144:1194: P_ACK_V1 kid=0 [ 40 ]
Sat Mar 05 19:11:10 2011 us=765000 TUN READ [19]
Sat Mar 05 19:11:10 2011 us=765000 UDPv4 WRITE [61] to x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=60
Sat Mar 05 19:11:10 2011 us=845000 TUN READ [86]
Sat Mar 05 19:11:10 2011 us=845000 UDPv4 WRITE [125] to x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=124
Sat Mar 05 19:11:10 2011 us=845000 TUN READ [70]
Sat Mar 05 19:11:10 2011 us=845000 UDPv4 WRITE [109] to x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=108
Sat Mar 05 19:11:10 2011 us=845000 TUN READ [78]
Sat Mar 05 19:11:10 2011 us=845000 UDPv4 WRITE [117] to x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=116
Sat Mar 05 19:11:11 2011 us=646000 UDPv4 READ [93] from x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=92
Sat Mar 05 19:11:11 2011 us=646000 TUN WRITE [52]
Sat Mar 05 19:11:12 2011 us=848000 TUN READ [86]
Sat Mar 05 19:11:12 2011 us=848000 UDPv4 WRITE [125] to x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=124
Sat Mar 05 19:11:13 2011 us=589000 UDPv4 READ [93] from x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=92
Sat Mar 05 19:11:13 2011 us=589000 TUN WRITE [52]
Sat Mar 05 19:11:14 2011 us=850000 TUN READ [70]
Sat Mar 05 19:11:14 2011 us=850000 UDPv4 WRITE [109] to x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=108
Sat Mar 05 19:11:15 2011 us=341000 TUN READ [42]
Sat Mar 05 19:11:15 2011 us=351000 TEST ROUTES: 0/0 succeeded len=-1 ret=1 a=0 u/d=up
Sat Mar 05 19:11:15 2011 us=351000 Initialization Sequence Completed
Sat Mar 05 19:11:15 2011 us=351000 UDPv4 WRITE [77] to x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=76
Sat Mar 05 19:11:15 2011 us=431000 TUN READ [42]
Sat Mar 05 19:11:15 2011 us=431000 UDPv4 WRITE [77] to x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=76
Sat Mar 05 19:11:15 2011 us=551000 UDPv4 READ [93] from x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=92
Sat Mar 05 19:11:15 2011 us=551000 TUN WRITE [52]
Sat Mar 05 19:11:15 2011 us=772000 TUN READ [19]
Sat Mar 05 19:11:15 2011 us=772000 UDPv4 WRITE [61] to x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=60
Sat Mar 05 19:11:16 2011 us=433000 TUN READ [42]
Sat Mar 05 19:11:16 2011 us=433000 UDPv4 WRITE [77] to x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=76
Sat Mar 05 19:11:17 2011 us=514000 TUN READ [110]
Sat Mar 05 19:11:17 2011 us=514000 UDPv4 WRITE [133] to x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=132
Sat Mar 05 19:11:17 2011 us=594000 UDPv4 READ [93] from x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=92
Sat Mar 05 19:11:17 2011 us=594000 TUN WRITE [52]
Sat Mar 05 19:11:17 2011 us=594000 TUN READ [54]
Sat Mar 05 19:11:17 2011 us=594000 UDPv4 WRITE [93] to x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=92
Sat Mar 05 19:11:17 2011 us=725000 TUN READ [175]
Sat Mar 05 19:11:17 2011 us=725000 UDPv4 WRITE [213] to x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=212
Sat Mar 05 19:11:18 2011 us=265000 TUN READ [110]
Sat Mar 05 19:11:18 2011 us=265000 UDPv4 WRITE [133] to x.x.x.144:1194: P_DATA_V1 kid=0 DATA len=132
Sat Mar 05 19:11:18 2011 us=345000 TUN READ [54]
Sat Mar 05 19:11:18 2011 us=345000 NOTE: --mute triggered...

TUN works on that recalcitrant WinXP client, TAP doesn't. Mysterious! Is this common? I need UNC (Universal Naming Convention) NetBIOS CLI functionality, e.g. "dir \\MACHINENAME\C\WINDOWS"... How to get it without TAP??

CLI Usage (Windows)
---------

Who knew?

With "dev tun", this works:
net use \\10.8.0.6 /USER:["]user[ ]name["] password

You can also authenticate the GUI way, with Windows Explorer (explorer.exe):
Start ==> Run ==> type "\\10.8.0.6" without quotes
and enter user/pass credentials as required, then see remote shares.

That enables file sharing on the CLI (or in Explorer). You can:
dir \\10.8.0.6\L\OPENVPN
type \\10.8.0.6\L\OPENVPN\LICENSE.TXT
notepad \\10.8.0.6\L\OPENVPN\HOWTO.TXT
etc.

Or, for example,
copy \\10.8.0.6\L\OPENVPN\HOWTO.TXT \\10.8.0.10\L\OPENVPN\HOWTO.TXT
between two concurrently-connected remote Clients.

Not typical command-line UNC procedure, but just as functional. I still don't understand why the TAP adapter doesn't work on my WinXP client, but this TUN solution meets my CLI needs fully.

Apologies for blathering at such length. After 3 days, I was out of answers and needed help -- but the problem simply wanted a 4th day. Case closed.