SSH

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General

ssh user@host

ssh user@host -p 123
 # specify alternate port

"Make sure you use full disk encryption and never stand up from your machine without locking it, and make sure you keep your local machine patched. If I get code execution on your machine, I am going to use whatever keys are loaded in your ssh-agent to pivot, hijack your existing open sessions, or modify your ssh client to dump the keys I need. ... Key length is a protection against the future, and against state level actors. Right now, key length doesn't matter much to me because I'm more focused on just stealing your keys from you regardless of length."

Server and client

The OpenSSH suite consists of the following tools:

  • Remote operations are done using ssh, scp, and sftp.
  • Key management with ssh-add, ssh-keysign, ssh-keyscan, and ssh-keygen.
  • The service side consists of sshd, sftp-server, and ssh-agent.
  • Dropbear is a relatively small SSH server and client. It runs on a variety of POSIX-based platforms. Dropbear is open source software, distributed under a MIT-style license. Dropbear is particularly useful for "embedded"-type Linux (or other Unix) systems, such as wireless routers.

Server

Client

Management

storm

  • storm is a command line tool to manage your ssh connections. features; adding, editing, deleting, listing, searching across your SSHConfig. command alias support for your CLI preferences. support for custom SSH directives. scriptable as a python library.

user interfaces besides cli. (web ui, wxpython, unity(ubuntu) indicator.) [5]

multissh

  • multissh - A really short but useful shellscript for connecting to all nodes of a cluster using ssh (also thru gateways and trapdoors) and sending commands to all nodes in parallel. It's using DCOP to remote-control a konsole process with the ssh connections in seperate tabs.

Keys

Default file name format;

~/.ssh/id_rsa and ~/.ssh/id_rsa.pub
  RSA key
~/.ssh/identity and ~/.ssh/identity.pub
  DSA key (old)

Creating

ssh-keygen
  create a key. rsa is default.

Distributing

ssh-copy-id [-i [identity_file]] [user@]remote

ssh-copy-id username@remote-server.org
ssh-copy-id 'user@remote-server.org -p 8129'

ssh-copy-id -i ~/.ssh/id_ecdsa.pub '-p 221 username@remote-server.org'

Multiple keys

ssh -i ~/.ssh/id_rsa_example.org

Config

~/.ssh/config

Host example.org
 IdentityFile ~/.ssh/id_rsa_example.org
  • sshit - A quick way to manage .ssh/config

SSH agent


  • Envoy helps you to manage ssh keys in similar fashion to keychain, but done in c, takes advantage of cgroups and systemd.

to sort


randomart

VisualHostKey=yes

SCP

scp -P [port] file.txt user@remotehose:~/file.txt

When scp on remote is initiated, it done so with -t flag, which is undocumented but might be required for precise command persmission configuration.


SSHFS

sshfs user@address:/home/user/dir dirtomountto -p [port]
  mount

fusermount -u dirtomountto
  unmount

if

fuse: failed to open /dev/fuse: Permission denied

do

usermod -G fuse [username]

and relogin

Security

fail2ban

sshguard

Honeypot

TOTP port fluxing

X11 forwarding

See GUI#X Forwarding

Web forwarding

Tools

To sort