CODEWITHSUNDEEP
sshssh-config
user1468980
user1468980

Reputation: 31

Dynamic aliases to host in ssh config

Imagine we a number of dynamic hosts of pattern

test-1.mydomain.com  
test-2.mydomain.com   
test-3.mydomain.com   
...  
test-n.mydomain.com

I'd like to SSH to each of those machines by not using full name (ssh test-7.mydomain.com), but simply by doing ssh test-7.

Is there a way to use SSH config to do pattern-like aliases like this?

Upvotes: 2

Views: 2260

Answers (3)

spazm
spazm

Reputation: 4809

Yes!

Yes, there is a way to do this directly in your ssh configuration.

  1. host allows PATTERNS
  2. hostname allows TOKENS

How:

Add this snippet to your ssh configuration ~/.ssh/config:

# all test-* hosts should match to test-*.mydomain.example.com
host test-*
    hostname %h.mydomain.example.com

Verify:

You can verify this with the -G flag to ssh. If your ssh is older and does not support -G you can try parsing verbose ssh output.

# if your ssh supports -G
% ssh test-17 -G | grep hostname
hostname test-17.mydomain.example.com


# if your ssh does not support -G
% ssh -v -v test-n blarg >/dev/null 2>&1 | grep resolv
debug2: resolving "test-n.mydomain.example.com" port 22
ssh: Could not resolve hostname test-n.mydomain.example.com: Name or service not known

Notes:

Ssh uses the first host line that matches. It is good practice to add your PATTERN host lines at the bottom of your configuration file.

If your test-n name patterns contain only a single character suffix, then you can use a ? pattern to make a less greedy match. test-? will match test-1 test-a test-z but not test-10

Upvotes: 3

Simon Doppler
Simon Doppler

Reputation: 2093

If it is an option for you, you could add a search domain in the resolv.conf file (I'm assuming you are on Linux).

You would need to add a line like this:

search mydomain.com

which will have SSH (and most other apps) look for test-n, then test-n.mydomain.com.

If you are not managing the resolv.conf file yourself (if you use systemd-networkd or NetworkManager for example), you will have to ajust the search domains in their configuration files).

Upvotes: 0

Leandro Figueredo
Leandro Figueredo

Reputation: 686

You can create a ssh config file and pre setting your servers.

See this tutorial, i hope it helps you!

ssh config

You can also create a function in your bash file for ssh access.

Like this:


function ssh_test () {
  [[ $1 =~ ^('test-1'|'test-2'|'test-3')$ ]] || { echo 'Not a valid value !!' && return ;}
  domain=$1.mydomain.com
  ssh my_user@"$domain" 
}

Upvotes: 0

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