Billion Electric Company BIPAC 8501 Manuale Utente

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SHDSL VPN Firewall Bridge/Router 
 
Chapter 4: Configuration   
Click Apply after changing settings. 
 
L2TP over IPSec (L2TP/IPSec) VPN Connection 
IPSec: Enable for enhancing your L2TP VPN security. 
Authentication: Authentication establishes the integrity of the datagram and ensures it is not tampered 
with in transmit. There are three options, Message Digest 5 (MD5), Secure Hash Algorithm (SHA1) or 
NONE. SHA1 is more resistant to brute-force attacks than MD5, however it is slower. 
   MD5: A one-way hashing algorithm that produces a 128−bit hash. 
   SHA1: A one-way hashing algorithm that produces a 160−bit hash.  
Encryption: Select the encryption method from the pull-down menu. There are four options, DES3DES
AES and NONE. NONE means it is a tunnel only with no encryption. 3DES and AES are more powerful 
but increase latency. 
   DES: Stands for Data Encryption Standard, it uses 56 bits as an encryption method. 
 
3DES: Stands for Triple Data Encryption Standard, it uses 168 (56*3) bits as an encryption 
method.  
 
AES: Stands for Advanced Encryption Standards, it uses 128 bits as an encryption method. 
Perfect Forward Secrecy: Choose whether to enable PFS using Diffie-Hellman public-key cryptography 
to change encryption keys during the second phase of VPN negotiation. This function will provide better 
security, but extends the VPN negotiation time. Diffie-Hellman is a public-key cryptography protocol that 
allows two parties to establish a shared secret over an unsecured communication channel (i.e. over the 
Internet). There are three modes, MODP 768-bit, MODP 1024-bit and MODP 1536-bit. MODP stands for 
Modular Exponentiation Groups. 
Pre-shared Key: This is for the Internet Key Exchange (IKE) protocol, a string from 4 to 128 characters. 
Both sides should use the same key. IKE is used to establish a shared security policy and authenticated 
keys for services (such as IPSec) that require a key. Before any IPSec traffic can be passed, each router 
must be able to verify the identity of its peer. This can be done by manually entering the pre-shared key 
into both sides (router or hosts). 
Remote Host Name (Optional): Enter hostname of remote VPN device. It is a tunnel identifier from the 
Remote VPN device matches with the Remote hostname provided.    If remote hostname matches, tunnel 
will be connected; otherwise, it will be dropped.   
Cautious:  This is only when the router performs as a VPN server.  This option should be used by 
advanced users only.       
Local Host Name (Optional): Enter hostname of Local VPN device that is connected / establishes a 
VPN tunnel.    As default, Router’s default Hostname is home.gateway. 
   
Tunnel Authentication: This enables router to authenticate both the L2TP remote and L2TP host.    This 
is only valid when L2TP remote supports this feature.   
Secret:  The secure password length should be 16 characters which may include numbers and 
characters. 
Click Apply after changing settings. 
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