1-9
Cisco ASA Series CLI Configuration Guide
Chapter 1 Configuring IPsec and ISAKMP
Configuring ISAKMP
Table 1-1
IKEv1 Policy Keywords for CLI Commands
Command
Keyword
Meaning
Description
authentication
rsa-sig
A digital certificate with
keys generated by the
RSA signatures algorithm
Specifies the authentication method the ASA uses to
establish the identity of each IPsec peer.
crack
Challenge/Response for
Authenticated
Cryptographic Keys
CRACK provides strong mutual authentication when the
client authenticates using a legacy method such as
RADIUS, and the server uses public key authentication.
pre-share
(default)
Preshared keys
Preshared keys do not scale well with a growing network
but are easier to set up in a small network.
encryption
des
3des
(default)
56-bit DES-CBC
168-bit Triple DES
Specifies the symmetric encryption algorithm that protects
data transmitted between two IPsec peers. The default is
168-bit Triple DES.
hash
sha
(default)
SHA-1 (HMAC variant)
Specifies the hash algorithm used to ensure data integrity. It
ensures that a packet comes from where it says it comes
from and that it has not been modified in transit.
md5
MD5 (HMAC variant)
The default is SHA-1. MD5 has a smaller digest and is
considered to be slightly faster than SHA-1. A successful
(but extremely difficult) attack against MD5 has occurred;
however, the HMAC variant IKE uses prevents this attack.
group
1
Group 1 (768-bit)
Specifies the Diffie-Hellman group identifier, which the
two IPsec peers use to derive a shared secret without
transmitting it to each other.
The lower the Diffie-Hellman group number, the less CPU
time it requires to execute. The higher the Diffie-Hellman
group number, the greater the security.
AES support is available on security appliances licensed for
VPN-3DES only. To support the large key sizes required by
AES, ISAKMP negotiation should use Diffie-Hellman
(DH) Group 5.
2
(default)
Group 2 (1024-bit)
5
Group 5 (1536-bit)
lifetime
integer value
(86400 =
default)
120 to 2147483647
seconds
Specifies the SA lifetime. The default is 86,400 seconds or
24 hours. As a general rule, a shorter lifetime provides more
secure ISAKMP negotiations (up to a point). However, with
shorter lifetimes, the ASA sets up future IPsec SAs more
quickly.
Table 1-2
IKEv2 Policy Keywords for CLI Commands
Command
Keyword
Meaning
Description
integrity
sha
(default)
SHA-1 (HMAC variant)
Specifies the hash algorithm used to ensure data integrity. It
ensures that a packet comes from where it says it comes
from and that it has not been modified in transit.
md5
MD5 (HMAC variant)
The default is SHA-1. MD5 has a smaller digest and is
considered to be slightly faster than SHA-1. A successful
(but extremely difficult) attack against MD5 has occurred;
however, the HMAC variant IKE user prevents this attack.
Summary of Contents for 5505 - ASA Firewall Edition Bundle
Page 28: ...Glossary GL 24 Cisco ASA Series CLI Configuration Guide ...
Page 61: ...P A R T 1 Getting Started with the ASA ...
Page 62: ......
Page 219: ...P A R T 2 Configuring High Availability and Scalability ...
Page 220: ......
Page 403: ...P A R T 2 Configuring Interfaces ...
Page 404: ......
Page 499: ...P A R T 2 Configuring Basic Settings ...
Page 500: ......
Page 533: ...P A R T 2 Configuring Objects and Access Lists ...
Page 534: ......
Page 601: ...P A R T 2 Configuring IP Routing ...
Page 602: ......
Page 745: ...P A R T 2 Configuring Network Address Translation ...
Page 746: ......
Page 845: ...P A R T 2 Configuring AAA Servers and the Local Database ...
Page 846: ......
Page 981: ...P A R T 2 Configuring Access Control ...
Page 982: ......
Page 1061: ...P A R T 2 Configuring Service Policies Using the Modular Policy Framework ...
Page 1062: ......
Page 1093: ...P A R T 2 Configuring Application Inspection ...
Page 1094: ......
Page 1191: ...P A R T 2 Configuring Unified Communications ...
Page 1192: ......
Page 1333: ...P A R T 2 Configuring Connection Settings and QoS ...
Page 1334: ......
Page 1379: ...P A R T 2 Configuring Advanced Network Protection ...
Page 1380: ......
Page 1475: ...P A R T 2 Configuring Modules ...
Page 1476: ......
Page 1549: ...P A R T 2 Configuring VPN ...
Page 1550: ......
Page 1965: ...P A R T 2 Configuring Logging SNMP and Smart Call Home ...
Page 1966: ......
Page 2059: ...P A R T 2 System Administration ...
Page 2060: ......
Page 2098: ...1 8 Cisco ASA Series CLI Configuration Guide Chapter 1 Troubleshooting Viewing the Coredump ...
Page 2099: ...P A R T 2 Reference ...
Page 2100: ......