Telnet and SSH
Telnet and SSH are the protocols to access your Networking Devices remotely to communicate (monitor, configure, modification). by using telnet and ssh protocol network engineer / network administrator access devices virtually.
Telnet and SSH is primarily source to access devices virtually from remote location by network engineer. to use these protocols you need to have software such as Putty, SecureCRT etc.
Telnet and SSH are the Layer 7 Protocol (Application Layer) and both communicate via TCP (Transmission Control Protocol).
Download Software used to access remotely
Telnet is a network protocol which allows network engineer to access devices virtually from remote location. Telnet is the most used protocol by network engineers.
Telnet use TCP port Number 23 by default. to access any device using Telnet, Telnet must be configured on device.
Telnet is an un-secure Protocol which is the biggest disadvantage of this protocol. Telnet transport data including userID and password over Network in clear text (means user readable format).
Telnet is designed to access networking devices virtual from remote location within LAN (Local Area Network)
Telnet is not using any security mechanism to encrypt / secure data communication over network that is why this protocol is no more used to access network devices on public network.
Telnet used IP address to reach any device as you can see below.
SSH is also a network protocol which used to access network device virtually from remote location. this is only the protocol available to access devices remotely and securely in public networks.
SSH is using Strong Authentication method to encrypt the data including UserID and Password when transmitting data over the network.
SSH uses the TCP port 22 by default. to access any network device from remotely, SSH must be configured on device.
SSH provide secure communication over the un-secure public network such as internet. it use the Public key to authenticate user.
It protects networks from attack like IP spoofing, DNS spoofing etc. any he/she (hacker) can’t hijack the traffic when Encryption is enable using SSH.
this is how you can use putty to access network device with SSH
Telnet VS SSH
- SSH is secure compare to telnet protocol
- SSH encrypt data when transport over network, where Telnet is sending in Plain Text.
- SSH use Public key for authentication and telnet not using any authentication to encrypt.
- SSH and Telnet is used for same purpose.
Telnet and SSH, Where to use Which Protocol
Telnet: As we know that telnet is un-secure protocol, So it is recommended to use this protocol only in LAN (Local Area Network).
Telnet use TCP port Number 23 by default.
Telnet should not be used over un-secure network like Internet. if you use this protocol on un-secure network any hacker can easily access / capture your data from network and then after hacker can access your network and might be infect your network with virus or encrypt your data and ask you for ransom.
SSH: As we know that SSH is a secure protocol which use strong authenticate and encrypt data when transporting over the network. so we can use SSH protocol to access your network devices from remote location via third party network / un-secure protocol (internet)
SSH should be used when accessing via public network / un-secure network but also can be used for LAN (Local Area Network) in order to provide additional security.
As a Network Engineer we should always look forward to provide double layer of protection when it comes to secure network and Data, so we should use Telnet in LAN and SSH in Public Network (Internet)
Telnet and SSH are very useful protocol for Network Engineers