Ssh – When logged into a Linux system, can I find the ip addresses which can be used to connect to the machine via ssh

ifconfigipnetworkingssh

In our lab, we have a Linux server that we can log onto locally or ssh into with a specific IP. When I am logged into the machine, I can see its internal IP with ifconfig or ip a and I can see its external IP through something like curl icanhazip.com. However, the external IP reported by that last command, is different from the one I type in when using ssh to connect to the machine, I believe the reported IP is the IP of our router.

When I am logged into the machine locally, is it possible for me to find out which IP addresses can be used to ssh into the system (not the IP addresses of the users that are logged in, but rather what IP addresses I can use with the ssh ###.###.###.### command). I would like to find this out without logging into the router admin panel to see what IP addresses and ports are being forwarded. Would the ssh IP addresses be stored in a file (I could not find anything in /etc/sshd_config), or is there a command that I can run to display it, like with the internal IP?

Best Answer

Many utilities will show the user's IP address, including who and w and last -ai.

Of course, if there is any form of redirection taking place, you may be looking at the machine that did the redirection.

Related Solutions

SSH – Set Local Terminal Colors to Match Remote Machine

Colors in terminals are determined in two steps:

the program running in the terminal tells the terminal to use a certain color number;
the terminal translates each color number into a color value.

Xterm has an escape sequence to change the color value associated with a color number. I don't remember whether PuTTY supports this sequence; I know Mintty does.

set_color_value () {
  printf "\\e]4;$1;$2\\a"
}
set_color_value 4 '#6495ed'  # set color 4 (blue) to CornflowerBlue

These settings won't survive a terminal reset. You can overcome this difficulty by appending the cursor configuration changing sequence to your terminal's reset string.

On a terminfo-based system using ncurses, save your terminal's terminfo settings to a file with infocmp >>~/etc/terminfo.txt. Edit the description to change the rs1 (basic reset) sequence, e.g. replace rs1=\Ec by rs1=\Ec\E]4;4;#6495ed\E\\. With some programs and settings, you may need to change the rs2 (full reset) as well. Then compile the terminfo description with tic ~/etc/terminfo.txt (this writes under the directory $TERMINFO, or ~/.terminfo if unset).
On a termcap-based system, grab the termcap settings from your termcap database (typically /etc/termcap). Change the is (basic reset) and rs (full reset) sequences to append your settings, e.g. :is=\Ec\Ec\E]4;4;#6495ed\E\\:. Set the TERMCAP environment variable to the edited value (beginning and ending with :).

Now you can put something like this in your ~/.profile:

if [ "$(ps -p $PPID -o comm=)" = sshd ] &&
   [ "$TERM" = "xterm" ]; then
  set_color_value … # set color scheme
  TERMCAP=…  # if necessary
fi

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