Create alias for ssh connecting

I'd like to speed up connecting to specific servers.

I have the servers let's say:

123.123.123.1
123.123.123.2
123.123.123.3

I normally connect with the following:

ssh -p 12345 [email protected]

This is a pain because the only difference between the servers is the last number of the ip.

I tried the following code:

alias ssht='{ ip=$(cat -); ssh -p 12345 my_user@"123.123.123.$ip"; }<<<'

However I get an error:

karl@karls-laptop ~/scripts $ ssht 1
Pseudo-terminal will not be allocated because stdin is not a terminal.

Is there a way to get this working?

Use the intended way and write the options and aliases into ~/.ssh/config:

Host 1
  Port 12345
  User my_user
  HostName 123.123.123.1

Host 2
  Port 12345
  User my_user
  HostName 123.123.123.2

and so on...

And then connect just using

ssh 1
ssh 2
...

This calls for a function -- simple and robust, whereas an alias in this case would be fragile.

Something like this should do:

function ssht () {
    [[ $1 =~ ^(1|2|3)$ ]] || { echo 'Not a valid last octet value !!' && return ;}
    ip=123.123.123.$1
    ssh my_user@"$ip" -p 12345
}

The condition [[ $1 =~ ^(1|2|3)$ ]] makes sure you have entered one of 1, 2, 3 as first argument (any trailing argument is ignored).

Now, you can give the desired last octet as the first argument:

ssht 1
ssht 2
ssht 3

Put this in your ~/.bashrc for having it available in any interactive session.