This program allows you to establish SSH connections using the MAC address of the machine you want to SSH into. This is useful if you have multiple devices you take with you to different DHCP networks and you want to be able to SSH into one from the other.
An alternate solution to this problem is
mDNS, and this will work better
in most situations, because it works with all kinds of connections, including
HTTP. However, if you're unable to install an mDNS server on each of your
devices, but you can install arp-scan, smh will be helpful to you. I
encountered this issue using Termux on a
rooted Android device, which prompted me to write this tool.
smh is just a wrapper around ssh, so ssh is one dependency.
You'll also need a working installation of arp-scan in your path, as this is
the program smh uses to identify devices on your network.
SMH only uses EUI-48 MAC addresses, and IPv4 addresses, so your devices and networks will need to use these. As far as I know, pretty much every device and network will use these.
Hopefully I'll get around to packaging this, but for now you'll need to install
from source. Just make sure you have a rust toolchain installed (cargo, etc.),
then run these commands:
git clone https://github.com/jpear1/smh.git
cd smh
cargo build --release
cp target/release/smh <directory-in-path>
where <directory-in-path> is where you usually put your binaries. /usr/bin,
for example.
SSH's destination field is on the form [user@]hostname or
ssh://[user@]hostname[:port]. If hostname is a MAC address, SMH will replace
hostname with the corresponding IP address. If hostname is a configured
name, SMH will replace hostname with the IP address that identifies a device
with the configured MAC address.
Except for this one change, SMH will forward all other arguments to SSH.
Here's a couple of examples:
smh user@12:34:56:78:9a:bc
Establishes an SSH connection to the device with MAC address 12:34:56:78:9a:bc
smh user@my-phone
Looks up my-phone to see if it has a configured MAC address. If it does,
replaces my-phone with corresponding IP address, otherwise forwards my-phone
to ssh.
SMH is configured with ~/.config/smh/hosts.toml. There should be one table,
[Hosts], then as many hostname = "<MAC-address>" entries as you please.
Ex.
# ~/.config/smh/hosts.toml
[Hosts]
foo = "aa:aa:aa:aa:aa:aa"
bar = "bb:bb:bb:bb:bb:bb"
Note that if you want to put dots in your hostname, you need to enclose the hostname in quotes. So, write:
"phone.local" = "cc:cc:cc:cc:cc:cc"
Don't write:
phone.local = "cc:cc:cc:cc:cc:cc"
arp-scan requires root permissions to run, so you'll need to run smh with
sudo smh hostname and put your config in /root/.config/smh/hosts.toml, or
configure your system to give target users permission to run smh as root. You
can do this with:
sudo su
chown root:smhers smh
chmod =2750 smh
Then add any users who should be able to use smh to the smhers group with:
usermod -a -G smhers <username>