Ssh Packet



Secure Shell (SSH) is a replacement for older remote shell programs such as telnet. SSH uses encryption to protect the contents (most notably passwords) being sent over its connection. Ssh/idrsa-bbinfoodle (0x55c97a2fa0a0), explicit debug3: send packet: type 5 debug3: receive packet: type 6 debug2: serviceaccept: ssh-userauth. Umumiy Internet kabi xavfsizlik muhim bo'lgan tizimlarda telnet protokolidan.

Secure Shell (SSH) is a replacement for older remote shell programs such as telnet. SSH uses encryption to protect the contents (most notably passwords) being sent over its connection.

History

XXX - add a brief description of SSH history

Protocol dependencies

  • TCP: Typically, SSH uses TCP as its transport protocol. The well known TCP port for SSH traffic is 22.

Example traffic

XXX - Add example traffic here (as plain text or Wireshark screenshot).

Wireshark

Packet Tracer Configure Ssh

The SSH dissector in Wireshark is functional, dissecting most of the connection setup packets which are not encrypted.

Unlike the TLS dissector, no code has been written to decrypt encrypted SSH packets/payload (yet). This is also not possible unless the shared secret (from the Diffie-Hellman key exchange) is extracted from the SSH server or client (see, as an example of a mechanism to extract internal information of that sort, the 'SSLKEYLOGFILE' method in TLS). Work on SSH2 decryption is tracked at https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=16054

Preference Settings

The SSH dissector has a preference to determine whether it should reassemble PDUs spread across multiple TCP segments. For this to work the TCP option 'Allow subdissectors to reassemble TCP streams' must be enabled.

Example capture file

XXX - Add a simple example capture file to the SampleCaptures page and link from here. Keep it short, it's also a good idea to gzip it to make it even smaller, as Wireshark can open gzipped files automatically.

Display Filter

A complete list of SSH display filter fields can be found in the display filter reference

  • Show only the SSH based traffic:

Capture Filter

You cannot directly filter SSH protocols while capturing. However, if you know the TCP port used (see above), you can filter on that one.

External links

  • RFC 4250 - The Secure Shell (SSH) Protocol Assigned Numbers

  • RFC 4251 - The Secure Shell (SSH) Protocol Architecture

  • RFC 4252 - The Secure Shell (SSH) Authentication Protocol

  • RFC 4253 - The Secure Shell (SSH) Transport Layer Protocol

  • RFC 4254 - The Secure Shell (SSH) Connection Protocol

  • RFC 4419 - Diffie-Hellman Group Exchange for the Secure Shell (SSH) Transport Layer Protocol

  • RFC 5656 - Elliptic Curve Algorithm Integration in the Secure Shell Transport Layer

  • Other documents from the concluded Secure Shell (secsh) IETF working group

  • IANA: Secure Shell (SSH) Protocol Parameters

Discussion

Configuration of SSH on Cisco Switch in Packet Tracer 2019

This Article is about the configuration of SSH on Cisco Switch. You can configure SSH on Cisco devices very easily using these simple steps:

  1. Crate a Packet Tracer Topology Lab
  2. Basic IP Setting for connectivity
  3. Set hostname and domain-name on Switch
  4. Set console and enable password for SSH login
  5. Generate the RSA Keys
  6. Setup the Line VTY configurations
  7. Create the username password for SSH access from PC
  8. Verify SSH access

For the configurations of SSH in packet tracer on Cisco switch, you are required to follow the above steps. Let start and perform these steps one by one. (Learn what is PSSH)

Crate a Packet Tracer Topology Lab

Our first step is to open the packet tracer and need to create a simple lab. For this topology we will use only one switch and a PC. Simply drag these two items on dashboard. Now we will connect them with straight through connection.

Basic IP Setting for connectivity

The next step is assign the suitable IP setting to these devices. For keeping it simple and making basic connectivity we will assign just two IP address to these device. We will assign the IP address to PC. For this will open the PC setting and then IP configuration. Here we will assign an IP address to host, in our case we are going to assign it 192.168.1.1 with the default gateway. For default gateway we will assign the IP address 192.168.1.10. We assign the second IP address to our Vlan1 interface on switch. And its IP address will be the gateway of host that is 192.168.1.10. For this we will use the basic commands.
Switch> enable

Switch# config t

Switch(config)#interface vlan 1

Switch (config-if)# ip address 192.168.1.10 255.255.255.0

Switch (config -if)#no shut

Once you done with basic IP setting, you can verify the connectivity by pinging the interface vlan1 IP from host.

Set host-name and domain-name on Switch

For SSh configurations you need to configure a host-name and domain-name for your switch you can do this with these simple commands.

Switch # config t

Switch (config)#hostname SW1

SW1 ( config)#ip domain-name w7cloud.com

Set console and enable password for SSH login

For SSH access it is required that you must configure the console and enable password on your cisco switch. You can set these two passwords with following commands.

SW1 ( config)#line console 0

SW1(config-line)#password cisco

SW1(config -line)#logging synchronous

SW1(config- line)#login local

SW1 (config- line)#exit

SW1 # enable secret cisco

Generate the RSA Keys

Your Cisco switch must have RSA keys that for the SSH process. You can generate the RSA keys with following command:

SW1 ( config)# crypto key generate rsa

How many bits in the modulus [512]: 1024

% Generating 1024 bit RSA keys, keys will be non-exportable…[OK]

Set the size of key to 1024 bits.

If your Cisco Switch is running an older version of Cisco IOS image, then it is extremely recommended that you upgrade to latest Cisco IOS.

Type

Setup the Line VTY configurations

For the configuration of SSH on cisco switch you need the following line vty configurations, and input transport is required to set to SSH. Set the login-to-local, & password to 7.

sw1 ( config)#line vty 0 4

sw1 ( config-line)#transport input ssh

sw1( config -line)#login local

sw1(config- line)#password 7

sw1(config- line ) #exit

Create the username password for SSH access from PC

If you do not have a username for SSH access you need to create a username. You can do it with this simple command:

Sw1# config t

sw1 (config ) # username w7cloud password cisco

Make sure the password encryption services is enabled on your switch, this service will encrypt your password, & when you do “sh run”, you’ll see only the encrypted password, not clear text password.

Packet

SW1# service password-encryption

Verify SSH access from Host

Once you done with the above configurations you can test all these configuration by creating a SSH connection from Host. You do it the command ssh –l <username> <IP address>. Open the host command prompt and use the command

Ssh Packet Too Long

C:>ssh -l waqas 192.168.1.10

It will ask for password, provide the password that you created with this username in previous steps. Then it asked for console password and then you need to provide the enable password. Now you are in your Cisco switch. You can perform switch configurations from your host.

From the switch, if you use the command ‘sh ip ssh’, it will also confirm that SSH is enabled on this cisco swith.

For better understanding please watch the video and like it.


I hope this will be a helpful for you, please share your comments. If you like this then share this on social media. Thank you for reading this..!

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