SSH Utilities

Stop SSH connection from freezing

On the client machine in /etc/ssh/ssh_config add the following:

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Host *
ServerAliveInterval 100

ServerAliveInterval: The client will send a null packet to the server every 100 seconds to keep the connection alive

NULL packet: This is sent by the server to the client. The same packet is sent by the client to the server. A TCP NULL packet does not contain any controlling flag like SYN, ACK, FIN etc. because the server does not require a reply from the client.

On the server in /etc/ssh/sshd_config add the following:

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ClientAliveInterval 60
TCPKeepAlive yes
ClientAliveCountMax 10000

ClientAliveInterval: The server will wait 60 seconds before sending a null packet to the client to keep the connection alive

TCPKeepAlive: This Is there to ensure that certain firewalls don't drop idle connections.

ClientAliveCountMax: Server will send alive messages to the client even though it has not received any message back from the client.

Depending on the machine, restart the ssh process

Linux Server: service sshd restart

Linux Client: service ssh restart

Mac Client:

Stop the Service - sudo launchctl stop com.openssh.sshd

Start the Service - sudo launchctl start com.openssh.sshd

Aliases

Open ~/.ssh/config and add the config given below:

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Host webserver
    HostName 1.2.3.4
    User root

Host website
    HostName site.example.com
    User user

Host site2
    HostName 2.3.4.5
    User root
    Port 2233

Host ubuntu
    HostName 192.168.225.50
    User root
    IdentityFIle ~/.ssh/key_name

After adding the config, you could ssh into the respective server by using ssh <alias_name>