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"wlan-through-vpn" setup (ipsec)
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Holly
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Joined: 08 Mar 2003
Posts: 67

PostPosted: Sun Dec 21, 2003 10:41 pm    Post subject: "wlan-through-vpn" setup (ipsec) Reply with quote

I'm going to set up a WLAN at home and have several questions. as i think the wlan encryption is not secure enough, i want to tunnel the connection through a ipsec-vpn (super-freeswan).

the network-topology looks like the following. so far everything but the wlan-stuff exists.

Code:
                          <Internet>
                               |
                               | ppp0/eth2
                               |
                 eth0   192.168.100.42
192.168.0.0/24---------internet gateway
  ethernet          |-->and vpn server
                    |          |
                    |          | eth1
                    |          |
                    |   192.168.100.0/24 --------- 192.168.100.1
                    |      ethernet              Windows-Workstation
                  V |          |
                  P |          |
                  N |          |
                    |   192.168.100.100 (192.168.200.X ?)
                    |  WLAN Access Point
                    |          |
                    |          |
                    |          |
                    |-->192.168.200.0/24
                         <WLAN Clients>


so, the wlan-clients should only be able to connect to the vpn-server on 192.168.100.42 via their "normal" connection. but when they connect through the vpn, they should have access to the whole network (192.168.0.0/24, 192.168.100.0/24 and the internet).


the first question regards the routing to the access point. does it have to have an ip-adress in the ethernet-subnet 192.168.100.0/24 or in the wlan-subnet 192.168.200.0/24?

besides that i have some problems with ipsec. i'm currently testing it with the a windows xp machine (192.168.100.1).
the windows machine times out:
Code:
Error 792: The L2TP connection attempt failed because security negotiation timed out.


And i'm getting the following errormessages in syslog when i connect.
Code:
Dec 21 22:34:23 [pluto] packet from 192.168.100.1:500: ignoring Vendor ID payload [MS NT5 ISAKMPOAKLEY 00000003]
Dec 21 22:34:23 [pluto] "heartofgold"[1] 192.168.100.1 #1: responding to Main Mode from unknown peer 192.168.100.1
Dec 21 22:34:23 [pluto] "heartofgold"[1] 192.168.100.1 #1: Peer ID is ID_IPV4_ADDR: '192.168.100.1'
Dec 21 22:34:23 [pluto] "heartofgold"[1] 192.168.100.1 #1: sent MR3, ISAKMP SA established
Dec 21 22:34:23 [pluto] "heartofgold"[1] 192.168.100.1 #1: cannot respond to IPsec SA request because no connection is known for 192.168.100.42:17/0...192.168.100.1:17/1701
Dec 21 22:34:23 [pluto] "heartofgold"[1] 192.168.100.1 #1: sending encrypted notification INVALID_ID_INFORMATION to 192.168.100.1:500
Dec 21 22:34:24 [pluto] "heartofgold"[1] 192.168.100.1 #1: Quick Mode I1 message is unacceptable because it uses a previously used Message ID 0xa7daab92 (perhaps this is a duplicated packet)
Dec 21 22:34:24 [pluto] "heartofgold"[1] 192.168.100.1 #1: sending encrypted notification INVALID_MESSAGE_ID to 192.168.100.1:500



the connection in ipsec.conf:
Code:
conn heartofgold
   right=192.168.100.42
   left=%any
   rightsubnet=0.0.0.0/0
   auto=add


and this is what "ipsec auto --status" says, while i'm trying to connect:
Code:
000 interface ipsec0/eth1 192.168.100.42
000
000 algorithm ESP encrypt: id=3, name=ESP_3DES, ivlen=64, keysizemin=168, keysizemax=168
000 algorithm ESP auth attr: id=1, name=AUTH_ALGORITHM_HMAC_MD5, keysizemin=128, keysizemax=128
000 algorithm ESP auth attr: id=2, name=AUTH_ALGORITHM_HMAC_SHA1, keysizemin=160, keysizemax=160
000
000 algorithm IKE encrypt: id=65289, name=OAKLEY_SSH_PRIVATE_65289, blocksize=16, keydeflen=128
000 algorithm IKE encrypt: id=65005, name=OAKLEY_TWOFISH_CBC, blocksize=16, keydeflen=128
000 algorithm IKE encrypt: id=65004, name=OAKLEY_SERPENT_CBC, blocksize=16, keydeflen=128
000 algorithm IKE encrypt: id=6, name=OAKLEY_CAST_CBC, blocksize=8, keydeflen=128
000 algorithm IKE encrypt: id=3, name=OAKLEY_BLOWFISH_CBC, blocksize=8, keydeflen=128
000 algorithm IKE encrypt: id=7, name=OAKLEY_AES_CBC, blocksize=16, keydeflen=128
000 algorithm IKE encrypt: id=5, name=OAKLEY_3DES_CBC, blocksize=8, keydeflen=192
000 algorithm IKE hash: id=6, name=OAKLEY_SHA2_512, hashsize=64
000 algorithm IKE hash: id=4, name=OAKLEY_SHA2_256, hashsize=32
000 algorithm IKE hash: id=2, name=OAKLEY_SHA, hashsize=20
000 algorithm IKE hash: id=1, name=OAKLEY_MD5, hashsize=16
000 algorithm IKE dh group: id=1, name=OAKLEY_GROUP_MODP768, bits=768
000 algorithm IKE dh group: id=2, name=OAKLEY_GROUP_MODP1024, bits=1024
000 algorithm IKE dh group: id=5, name=OAKLEY_GROUP_MODP1536 (extension), bits=1536
000 algorithm IKE dh group: id=42048, name=OAKLEY_GROUP_MODP2048 (extension), bits=2048
000 algorithm IKE dh group: id=43072, name=OAKLEY_GROUP_MODP3072 (extension), bits=3072
000 algorithm IKE dh group: id=44096, name=OAKLEY_GROUP_MODP4096 (extension), bits=4096
000
000 stats db_ops.c: {curr_cnt, total_cnt, maxsz} :context={0,0,0} trans={0,0,0} attrs={0,0,0}
000
000 "heartofgold"[1]: 0.0.0.0/0===192.168.100.42...192.168.100.1
000 "heartofgold"[1]:   ike_life: 3600s; ipsec_life: 28800s; rekey_margin: 540s; rekey_fuzz: 100%; keyingtries: 1
000 "heartofgold"[1]:   policy: PSK+ENCRYPT+TUNNEL+PFS+DISABLEARRIVALCHECK; interface: eth1; unrouted
000 "heartofgold"[1]:   newest ISAKMP SA: #1; newest IPsec SA: #0; eroute owner: #0
000 "heartofgold"[1]:   IKE algorithms wanted: 5_000-1-5, 5_000-2-5, 5_000-1-2, 5_000-2-2, 5_000-1-1, 5_000-2-1, flags=-strict
000 "heartofgold"[1]:   IKE algorithms found:  5_192-1_128-5, 5_192-2_160-5, 5_192-1_128-2, 5_192-2_160-2, 5_192-1_128-1, 5_192-2_160-1,
000 "heartofgold"[1]:   IKE algorithm newest: 3DES_CBC_192-SHA-MODP1024
000 "heartofgold"[1]:   ESP algorithms wanted: 3_000-1, flags=-strict
000 "heartofgold"[1]:   ESP algorithms loaded: 3_168-1_096,
000 "heartofgold": 0.0.0.0/0===192.168.100.42...%any
000 "heartofgold":   ike_life: 3600s; ipsec_life: 28800s; rekey_margin: 540s; rekey_fuzz: 100%; keyingtries: 1
000 "heartofgold":   policy: PSK+ENCRYPT+TUNNEL+PFS+DISABLEARRIVALCHECK; interface: eth1; unrouted
000 "heartofgold":   newest ISAKMP SA: #0; newest IPsec SA: #0; eroute owner: #0
000 "heartofgold":   IKE algorithms wanted: 5_000-1-5, 5_000-2-5, 5_000-1-2, 5_000-2-2, 5_000-1-1, 5_000-2-1, flags=-strict
000 "heartofgold":   IKE algorithms found:  5_192-1_128-5, 5_192-2_160-5, 5_192-1_128-2, 5_192-2_160-2, 5_192-1_128-1, 5_192-2_160-1,
000 "heartofgold":   ESP algorithms wanted: 3_000-1, flags=-strict
000 "heartofgold":   ESP algorithms loaded: 3_168-1_096,
000
000 #1: "heartofgold"[1] 192.168.100.1 STATE_MAIN_R3 (sent MR3, ISAKMP SA established); EVENT_SA_REPLACE in 3328s; newest ISAKMP


i guess, i will be able to set the wlan up correctly when i have it, but ipsec is pain in the ass :?
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Holly
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Joined: 08 Mar 2003
Posts: 67

PostPosted: Mon Dec 22, 2003 9:59 pm    Post subject: Reply with quote

ok, the wlan itself works. the setup is a little different from the drawing above, but i think the changes don't regard the vpn.

i'm still stuck with that problem. connecting to the vpn via wlan doesn't change anything. does anybody have an idea?
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Holly
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Joined: 08 Mar 2003
Posts: 67

PostPosted: Tue Dec 23, 2003 8:11 pm    Post subject: Reply with quote

well, does anyone have *any* working (super-)freeswan config, that is similar to mine? i can't imagine, i'm the only one who uses this kind of setup.
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Holly
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Joined: 08 Mar 2003
Posts: 67

PostPosted: Wed Dec 24, 2003 2:24 am    Post subject: Reply with quote

i have some more information on my problem. i tcpdump'ed the traffic during a vpn-connection attempt (heartofgold is the server, deepthought the windows-client):
Code:
tcpdump: listening on eth1
03:15:00.791188 deepthought.1031 > heartofgold.domain:  107+ A? heartofgold. (39)
03:15:00.793457 heartofgold.domain > deepthought.1031:  107* 1/0/0 A[|domain] (DF)
03:15:00.818779 deepthought.1471 > heartofgold.1723: S 3870137625:3870137625(0) win 64240 <mss 1460,nop,nop,sackOK> (DF)
03:15:00.818976 heartofgold.1723 > deepthought.1471: R 0:0(0) ack 3870137626 win 0 (DF)
03:15:01.260230 deepthought.1471 > heartofgold.1723: S 3870137625:3870137625(0) win 64240 <mss 1460,nop,nop,sackOK> (DF)
03:15:01.260474 heartofgold.1723 > deepthought.1471: R 0:0(0) ack 1 win 0 (DF)
03:15:01.760968 deepthought.1471 > heartofgold.1723: S 3870137625:3870137625(0) win 64240 <mss 1460,nop,nop,sackOK> (DF)
03:15:01.761236 heartofgold.1723 > deepthought.1471: R 0:0(0) ack 1 win 0 (DF)
03:15:01.790607 deepthought.1031 > heartofgold.domain:  108+ A? heartofgold. (39)
03:15:01.791314 heartofgold.domain > deepthought.1031:  108* 1/0/0 A[|domain] (DF)
03:15:01.819599 deepthought.500 > heartofgold.500: isakmp: phase 1 I ident: [|sa]
03:15:01.819865 heartofgold > deepthought: icmp: heartofgold udp port 500 unreachable [tos 0xc0]
03:15:02.813509 deepthought.500 > heartofgold.500: isakmp: phase 1 I ident: [|sa]
03:15:02.813804 heartofgold > deepthought: icmp: heartofgold udp port 500 unreachable [tos 0xc0]
03:15:04.816631 deepthought.500 > heartofgold.500: isakmp: phase 1 I ident: [|sa]
03:15:04.818200 heartofgold.500 > deepthought.500: isakmp: phase 1 R ident: [|sa] (DF)
03:15:04.878904 deepthought.500 > heartofgold.500: isakmp: phase 1 I ident: [|ke]
03:15:04.912604 heartofgold.500 > deepthought.500: isakmp: phase 1 R ident: [|ke] (DF)
03:15:04.941091 deepthought.500 > heartofgold.500: isakmp: phase 1 I ident[E]: [encrypted id]
03:15:04.942899 heartofgold.500 > deepthought.500: isakmp: phase 1 R ident[E]: [encrypted id] (DF)
03:15:04.944568 deepthought.500 > heartofgold.500: isakmp: phase 2/others I oakley-quick[E]: [encrypted hash]
03:15:05.938233 deepthought.500 > heartofgold.500: isakmp: phase 2/others I oakley-quick[E]: [encrypted hash]
03:15:07.940526 deepthought.500 > heartofgold.500: isakmp: phase 2/others I oakley-quick[E]: [encrypted hash]
03:15:11.947012 deepthought.500 > heartofgold.500: isakmp: phase 2/others I oakley-quick[E]: [encrypted hash]
03:15:14.232225 deepthought.500 > heartofgold.500: isakmp: phase 2/others I inf[E]: [encrypted hash]
03:15:14.234019 heartofgold.500 > deepthought.500: isakmp: phase 2/others R inf[E]: [encrypted hash] (DF)


might the "udp port 500 unreachable" a problem? actually there should be no port blocked like with iptables.
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puke
Tux's lil' helper
Tux's lil' helper


Joined: 05 Oct 2002
Posts: 128

PostPosted: Fri Apr 16, 2004 12:51 pm    Post subject: Reply with quote

You must allow IPsec packets (IKE on UDP port 500 plus ESP, protocol 50) in and out of your gateway.

Ripped from freeswan.org:

Code:
# IKE negotiations
iptables -A INPUT  -p udp -i $world --sport 500 --dport 500 -j ACCEPT
iptables -A OUTPUT -p udp -o $world --sport 500 --dport 500 -j ACCEPT
# ESP encryption and authentication
iptables -A INPUT  -p 50 -i $world -j ACCEPT
iptables -A OUTPUT -p 50 -o $world -j ACCEPTOptionally, you could restrict this, allowing these packets only to and from a list of known gateways.
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