- Cisco Generate Crypto Key
- Cisco Asa Crypto Key Generate Rsa Modulus 1024 Command
- Cisco Asa Crypto Key Generate Rsa Modulus 1024 Command
Cisco IOS CA server configuration:
Notes:-– Certificate server must use the same name as the key pair.
– Default CA certificate lifetime 3 years and the default certificate lifetime is 1 year.
– Cisco IOS CA Server only supports enrollments done via Simple Certificate Enrollment Protocol (SCEP). For this to work, the built-in HTTP server must be enabled.
– 3 database levels, Minimum (default), Names and Complete.
– Use NTP to make sure the time is in sync with the enrolling parties.
Verification:
How I create RSA key and enable SSH access in Cisco VG202, in a Cisco router I use the next commands(but in a VG not exists): conf t. Crypto key generate rsa modulus 1024 ip domain-name domain-name ip ssh version 2 ip ssh time-out 120 ip ssh authentication-retries 3 line vty 0 4 transport input telnet ssh end. Re: crypto key generate rsa modulus 1024 on cisco 1800 series to create a Trustpoints Gus Feb 5, 2014 3:05 PM (en respuesta a Gustavo) Hola Gustavo, Hasta el dia de hoy veo tu post en el site. Crypto key generate rsa modulus 1024 (I typically do 2048) I know that's a requirement for ssh v2, but I'm not sure about ssh v1. The only other thing I can suggest is lower your ssh timeout so. Displaying the RSA Public Keys ASA5505# show crypto key mypubkey rsa Key pair was generated at: 19:24:29 BRT Nov 15 2009 Key name: RSA-Key Usage: General Purpose Key Modulus Size (bits): 1024 Key Data: 30819f30 0d06092a 864886f7 0d00381 8d08181 008e60c4 bce3e63a 47aa12c4 e78c0a76 f2faf41c 5d8d461a 4978a5f6 0a4ac11b.
LINQ to SQL does not support computed columns as primary keys. To designate a property or field as a primary key Add the IsPrimaryKey property to the ColumnAttribute attribute. Specify the value as true. Linq to sql auto generated primary key access. I am using LINQ To SQL and creating my database using CreateDatabase method. I understand from MSDN that the syntax to create an auto generated primary key field is Column(Storage='ID', IsPrimaryKey=true, AutoSync=AutoSync.OnInsert, DbType='Int NOT NULL IDENTITY', IsDbGenerated=true).
Cisco ASA enrollment to the Cisco IOS CA Server:
Notes:-– You may have to allow SCEP communication if there is an intermediary firewall between the Cisco ASA and the Cisco IOS CA Server. SCEP uses HTTP protocol for communication.
– Make sure the CA server is enabled. (no shutdown)
– Use NTP to make sure the time is in sync with the Cisco IOS CA Server.
Verification:
Last year, I wrote a post about securing the Cisco IOS SSH server. It also makes sense to create one for Cisco ASA especially when my old post about enabling SSH on Cisco ASA was back in 2012. That blog post didn’t include the advanced configurations that will improve the security of the Cisco ASA SSH server. With this post, I’d like to share the minimum advanced SSH configurations that network engineers should consider adding to their ASA template.
Enabling Cisco ASA SSH server
Before we can connect to our Cisco ASA via SSH, we need to have a checklist of things we need to configure.
- While it’s a good idea to have enable password configured, it is optional for SSH.
- You must have at least one user account locally.
- Configure ASA’s authentication method. The authentication method can be local, RADIUS, or TACACS+.
- Generate RSA key pair.
- Configure ACL to allow a specific IP address or range(s).
Setting enable password
My old post covered how to set enable password. It’s the same command on how to set the enable password, but in the newer ASA software, it uses PBKDF2 to encrypt the password compared to the MD5-based hash in older ASA software.
Generating RSA keys
As covered in my old post, to enable SSH on the ASA, we’ll need to generate RSA key pair first. Current NIST recommendation is to use 2048-bit or above. In this post, I am going to use 4096-bit key pair.
SSH Version
Configuring the Cisco ASA SSH server to accept only version 2 is best practice. The reason for this is because SSHv1 has vulnerabilities. That said, make sure to add this to your ASA template.
SSH Encryption Algorithms
By default, it seems that the ASA’s encryption algorithm is configured to use the medium settings. Unfortunately, I cannot seem to verify it using the show run all command. However, the combination of show ssh and show ssh ciphers does the trick.
The client and server negotiate the encryption algorithm. That said, it is possible that the client would pick a weaker cipher. To avoid that, we’re going to specify the use of a safer cipher. According to this thread, the use of EAX or GCM is preferable when available. If not, the use CTR over CBC mode. By specifying the encryption algorithm, we’re telling ASA to only offer the AES-256-CTR mode to any clients that try to connect to it.
Cisco Generate Crypto Key
Here’s the verbose output of my SSH to a Cisco ASA using the default SSH cipher encryption.
Generate random encryption key php. Let’s configure the ASA to only use AES256 CTR mode.
Here’s the verbose output of my SSH connection to a Cisco ASA device using the SSH cipher encryption configuration mentioned above.
SSH Integrity Algorithm
By default, it seems that the ASA’s integrity algorithm is configured to use the medium settings. Unfortunately, I cannot seem to verify it using the show run all command. However, the combination of show ssh and show ssh ciphers does the trick.
The default setting for the ASA SSH integrity algorithm is medium. Which means, it will accept both HMAC-SHA1 and HMAC-SHA1-96. The difference between the two algorithms is the digest length. The HMAC-SHA1-96 is a truncated message digest. From my limited understanding, the HMAC-SHA1-96 is the weakened version of HMAC-SHA1 due to the shortened message digest.
Here’s the verbose output of my SSH to a Cisco ASA using the default SSH integrity algorithm.
Let’s configure the ASA to only use HMAC-SHA1.
Here’s the verbose output of my SSH connection to a Cisco ASA device using the SSH integrity algorithm configuration mentioned above.
SSH Key Exchange
The ASA support two Diffie-Hellman key exchange methods and these are DH Group 1 (768-bit) and DH Group 14 (2048-bit). By default, the ASA is set to use Diffie-Hellman Group 1. Unfortunately, this is below what NIST recommends to use in this day and age.
Here’s a Cisco ASA with default SSH key exchange configuration. I issued the no ssh key-exchange to be sure.
Here’s the verbose output of my SSH connection to a Cisco ASA using the default SSH key exchange.
Let’s configure the ASA to use DH Group 14.
Here’s the verbose output of my SSH connection to the Cisco ASA after changing the key exchange method.
SSH ACL
Restricting remote management to a certain IP address is a best practice. It is also required to add the ACL, or we won’t be able to access the Cisco ASA via SSH. That said, I included the command here.
Final Words
All of the configurations covered here are what I’d say minimum security standard for all Cisco ASA devices. It is, after all, a network security device, so it is a must to secure it properly. Though this post is just a small part of protecting the management plane and network engineers must incorporate other security configurations.
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Want to learn more about ASA?
Cisco ASA: All-in-one Next-Generation Firewall, IPS, and VPN Services (3rd Edition)
Cisco ASA for Accidental Administrators: An Illustrated Step-by-Step ASA Learning and Configuration Guide
Cisco Asa Crypto Key Generate Rsa Modulus 1024 Command
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Cisco Asa Crypto Key Generate Rsa Modulus 1024 Command
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