Internet Protocol Security (IPSec) Internet Key Exchange (IKE) BayRS Martin Isaksen WAN Architect Southern Region

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Internet Protocol Security (IPSec) Internet Key
Exchange (IKE)BayRS Martin IsaksenWAN
ArchitectSouthern Region
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What is IKE?

• IPSec provides the packet-level processing
• Internet Key Exchange negotiates security
  associations
• The IETF chose IKE as the standard method (RFC
  2409) of configuring security associations for
  IPSec.
• Based on ISAKMP protocol (RFC 2408) and Oakley
  Key Exchange specification.
• A UDP based protocol for negotiating security
  associations and providing authenticated key
  exchange for its clients
• Creates an authenticated, secure tunnel between
  two entities (IKE SA) and then negotiates the
  IPSec SA

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Authentication

• IPSec clients must be authenticated to each other
• This process requires that the two entities
  authenticate themselves to each other and
  establish shared keys.
• The two entities must agree on a common
  authentication protocol through a negotiation
  process, the following mechanisms are generally
  implemented
• Pre-shared keys
• Public key cryptography
• Digital signature
• V13.20 supports only Pre-shared key based
  authentication
• A Pre-shared key will need to be configured per
  IKE peer
• Manual key

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Key Exchange

• IPSec clients must have a shared session key in
  order to encrypt the IKE tunnel.

Pre-Shared Key
Pre-Shared Key
Session Key
Encrypted Session key
Encrypted Session key
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IPSec Tunneling (Manual Key) V13.10
IPSec ESP tunnel mode
HQ B
HQ A
NPK (MANUAL)
NPK (MANUAL)
IPSec Policies
Branch A-1
NPK (MANUAL)
Site Manager
Secret Keys (Manual)
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Manual Keying

• Disadvantages
• Manual intervention is needed to update or change
  the keys.
• Since manual changing of keys is normally
  infrequent, the attacker has more time to crack
  the key and to decrypt data.
• There is a chance of error in configuration since
  the same key needs to be configured on the two
  different endpoints of the IPSec tunnel.
• If the employee with access to the keys leaves or
  becomes untrustworthy, lengthy configuration
  changes need to take place.
• The keys in the configuration need to be
  protected in some manner from outside attack

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IPSec Tunneling (IKE) V13.20
IPSec ESP tunnel mode
HQ A
HQ B
IKE
NPK (MANUAL)
NPK (MANUAL)
IPSec Policies
IKE
Branch A-1
NPK (MANUAL)
Site Manager
Pre-Shared Secret Keys
Session Key
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IKE Negotiation vs. Manual Key

• Support for both IKE to negotiate security
  associations and using Manual keying is required
  by the IETF standard
• IKE Advantages
• The keys for security associations are generated
  by the IKE protocol
• The information to authenticate each IKE peer
  must be configured i.e. pre-shared key or
  certificate. (Pre-Shared Key Support only in
  13.20)
• The IKE protocol can change SA keys based on
  pre-configured criteria
• Elapsed time or number of bytes sent
• Re-keying requires no explicit manual
  intervention and happens faster
• No person has the knowledge of the keys being
  used to encrypt data since it is automatically
  generated
• Perfect Forward Secrecy (PFS) is achieved by
  using Diffie-Hellman to exchange keys for (IPSec)
  Security associations

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Added Encryption Integrity Support

• DES
• 3DES
• MD5 (128-bit digest)
• SHA-1 (160-bit digest)
• IKE Support only

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IKE Configuration Example
192.200.10.0
Outbound Policy Protect all traffic originating
from Local LAN and destined for the remote LAN
IPSec Interface
Local
.2
.1
Untrusted Network
Security Gateway
Security Gateway
NPK 0x1122334455667788
192.100.10.0
192.100.90.0
Sydney
Capetown
Proposal Syd_Cape_Outbound
3DES SHA-1
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TI Configuration

• At the TI Prompt

ksession Please enter password Entering Secure
Shell Session.SSHELLgt kseedTo initialize the
seed for the cryptographic randomnumber
generator, please now enter a series of
characterswhich you would consider to be
'random.' As you enter them,dots '.' will be
displayed to indicate progress. If your
stringis not 'random' enough, questions '?' will
be displayed. In thatcase, modify the pattern
you are entering. When enough data isinput, you
will be prompted to stop (near 3 lines of
input)....... .... .... .... .... .... ....
.... .... .... .... .All done, thank
you!SSHELLgt kset npk 0x2222000000002222 SSHELLgt
save config config SSHELLgt kexit

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V7.20 Site Manager Configuration..Protocol

• Click on WAN connector gt Add/Del Protocols gt
  Select IKE (automatically selects IPSEC) gt OK

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Creating Outbound Policy Templates

• Click on Outbound Policies

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Outbound Policy Template..

• Click on Template.. gt Create gt Supply Criteria
  Action

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Outbound Policy Template..

• Click on Template.. gt Create gt Supply Criteria
  Action gt OK gt Done

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Create Outbound Policy

• Click on Add Policy gt Supply Policy Name gt OK

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Choose SA Type

• Choose Automated SA

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NPK Value Required

• Supply NPK Value

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Proposal Policy

• Click on New Proposal

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Proposal Policy..

• Supply Proposal Name gt Select appropriate values
  gt Done

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IKE SA Destination

• Click on Add (SA Destination) gt Supply values gt
  Done

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SA Destination Proposals

• Select SA Destination Proposals gt OK gt Done
  gt Done

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IKE SA Expiry ValueMinutes

• Select Protocols gt IP gt IKE gt Select Expiry
  Value

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Log Output
11 log -eIPSEC -eIKE -eCAPI 7
11/02/1999 145635.714 INFO SLOT 1 IPSEC
Code 21Policy Gate initializing with GH
0xC00020BE 8 11/02/1999 145635.812 INFO
SLOT 1 IPSEC Code 28Finished
initializing the IPSec MIB, Interface 10.2.2.1,
circuit 2 9 11/02/1999 145635.820 INFO
SLOT 1 IPSEC Code 22IPSec Forwarding
gate initializing with GH 0xC00020C5IPSec
Tunnel Endpoint gate initializing with GH
0xC0002031 10 11/02/1999 145635.824 INFO
SLOT 1 IPSEC Code 24Tunnel Endpoint
gate registered successfully with IP for ESP
packets 11 11/02/1999 145636.398 INFO
SLOT 1 IKE Code 20Establishing IKE SA
from 10.2.2.1 to 10.2.2.2, ? SA being
establishedusing initiator role. 12
11/02/1999 145640.089 INFO SLOT 1 IKE
Code 21IKE SA from 10.2.2.1 to 10.2.2.2 is
up.Cipher DES, Hash SHA1, Life Type Minutes,
Life Time 480Establishing IPsec SA from
10.2.2.1 to 10.2.2.2 for policy 1using initiator
role, without perfect forward secrecy. Quick Mode
ID 0x75d57432. 13 11/02/1999 145640.277
INFO SLOT 1 IKE Code 28Quick Mode
exchange, ID 0x75d57432, from 10.2.2.1 to
10.2.2.2 is up.Sending negotiated SA information
for policy 1 to IPsec. 14 11/02/1999
145640.281 INFO SLOT 1 IPSEC Code
27Log Action Interface 10.2.2.1, Circuit 2,
Direction Outbound,Policy number 1
?Ping from host 2 to host 1 matches policyIP Pkt
Info Src 10.3.3.2, Dest 10.1.1.4, Prot 1,
Tot. Len 60

• Log output for correct IKE/IPSEC configuration

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Troubleshooting Tools

• Log Entities
• IPSEC, KEYMGR, CAPI, IKE
• Scripts
• ipsec.bat
• ipsec (embedded)
• MIB
• wfIkeDescriptorEntry
• wfIkTransformEntry

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Cisco Configuration

• Cisco to Contivity IPSEC Config

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BayRS to Contivity Interoperability

• BayRS uses IPSEC SAs - Conitivty uses Branch
  Tunnels
• BayRS uses policies Contvity uses remote and
  local
• networks
• BayRS uses policy proposal Contivity uses Group
  IPSEC
• BayRS IP address policy must match exactly as
  Contivity network address
• BayRS 10.1.1.0 to 10.1.1.255 (under policy
  template)
• Conitvity 10.1.1.0/255.255.255.0 (under remote
  networks)

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IPSEC Interoperability Notes

• BayRS only implements static routing with
  Contivity
• BayRS uses dynamic routing between BayRS routers
• Must use BayRS 14.00 or later
• BayRS and NAT IPSEC and NAT are not supported
  to work together (NAT will take precedence)
• BN - 3-DES throughput 1.5 Mbps 64 Byte Zero
  Loss
• PP5430 is even better

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References

• http//www.ietf.org/html.charters/ipsec-charter.ht
  ml
• The Internet Key Exchange (IKE), RFC 2409
• RFC 2401 - 2412 are IPSec related RFCs in one
  form or the other