Score:0

Server

How can I use regex for hostname in ssh_config?

nyxee

5/12/23, 2:22 PM

So, my local address keeps on changing on my Lan. Can't change the dhcp settings. Addresses are all like: 192.168.A.x, 192.168.A.y, 192.168.A.z. When I switch off the dhcp server, next time it gives 192.168.B.x, 192.168.B.y, 192.168.B.z. It keeps x, y and z constant.

So, i have tried to edit ~/. ssh/config like this

Host pc1
           HostName pc.local
           User xx
           Port 22

Host pc2
           HostName "192.168.???.n1"
           User xx
           Port 22

Host pc3
           HostName "192.168.*.n2"
           User xx
           Port 22

Calling ssh pc1 works fine. Also using ssh 192.168.A.x with the full adress works. But, calling ssh pc2 gives the error could not resolve hostname 192.168.???.n1

156

0 + 0

ubuntu

ssh

configuration

AlexD

5/12/23, 4:29 PM

Patterns can be used with `Host` but not in `Hostname`.

Score:3

Server

Gerald Schneider

5/12/23, 2:23 PM

No, you can't. Especially not in this case. How is the ssh client supposed to "guess" what IP you want to connect to?

Set up a proper DHCP server or configure static IPs on your servers.

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nyxee

5/12/23, 3:19 PM

Got some instructions from here: https://serverfault.com/questions/803902/how-can-i-match-a-cidr-range-for-an-ssh-config-host-entry/803906

Archemar

5/12/23, 3:52 PM

wildcard will work on `Host` line, e.g. `host 192.168.*.125<cr>user xx` would allow selecting user `xx` when using `ssh 192.168.33.125`

nyxee

5/13/23, 5:25 AM

@Archemar, how would I then access that via ssh command?? Do I use `Host 192.168.*.n1 pc2` then `ssh pc2`??

Archemar

5/13/23, 11:15 AM

by using `ssh 192.168.33.125` ssh can't do "retro aliasing" that DNS's work.

Score:1

Server

byaruhaf

5/13/23, 9:30 AM

it's not possible to use regex for hostname in ssh_config, but you can use the local domain name as you had done with PC1 thus

Host pc1
           HostName pc.local
           User xx
           Port 22

Host pc2
           HostName pc2.local
           User xx
           Port 22

Host pc3
           HostName pc3.local
           User xx
           Port 22

using the hostname you would never need to know the IP. Then you can ssh to the hostname

ssh pc.local

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Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: How can I use regex for hostname in ssh_config?

TH: ฉันจะใช้ regex สำหรับชื่อโฮสต์ใน ssh_config ได้อย่างไร

RO: Cum pot folosi regex pentru numele de gazdă în ssh_config?

RU: Как я могу использовать регулярное выражение для имени хоста в ssh_config?

VI: Làm cách nào tôi có thể sử dụng regex cho tên máy chủ trong ssh_config?

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