sshpiper

by tg123

tg123 / sshpiper

The missing reverse proxy for ssh scp

441 Stars 64 Forks Last release: 12 months ago (v0.4.2) MIT License 252 Commits 6 Releases

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SSH Piper

Go Go Report Card Docker Image

SSH Piper works as a proxy-like ware, and route connections by

username
,
src ip
, etc.
+---------+                      +------------------+          +-----------------+
|         |                      |                  |          |                 |
|   Bob   +----ssh -l bob----+   |   SSH Piper   +------------->   Bob' machine  |
|         |                  |   |               |  |          |                 |
+---------+                  |   |               |  |          +-----------------+
                             +---> pipe-by-name--+  |                             
+---------+                  |   |               |  |          +-----------------+
|         |                  |   |               |  |          |                 |
|  Alice  +----ssh -l alice--+   |               +------------->  Alice' machine |
|         |                      |                  |          |                 |
+---------+                      +------------------+          +-----------------+


Downstream SSH Piper Upstream

Demo

demo

asciicast

Install

Build yourself [Go 1.14+]

git clone 
cd sshpiper/sshpiperd/
go build

with pam module support

go build -tags pam 

with Docker image

docker run farmer1992/sshpiperd

Run with Workding Dir upstream driver

docker run -d -p 2222:2222 \
  -v /etc/ssh/ssh_host_rsa_key:/etc/ssh/ssh_host_rsa_key \
  -v /YOUR_WORKING_DIR:/var/sshpiper \
  farmer1992/sshpiperd

Run with Additional Challenge

use env

SSHPIPERD_CHALLENGER
to specify which challenger to use
docker run -d -p 2222:2222 \
  -e SSHPIPERD_CHALLENGER=pam \
  -v /YOUR_PAM_CONFIG:/etc/pam.d/sshpiperd \
  -v /etc/ssh/ssh_host_rsa_key:/etc/ssh/ssh_host_rsa_key \
  -v /YOUR_WORKING_DIR:/var/sshpiper \
  farmer1992/sshpiperd

with Snap

Get it from the Snap Store

sudo snap install sshpiperd

configure with snap

sudo snap set sshpiperd 'port=3333'

sudo snap restart sshpiperd

NOTE: * Default working dir for snap verion is

/var/snap/sshpiperd/common
* use classic mode if PAM is not working:
sudo snap install --classic sshpiperd

Quick start

Just run

showme.sh
in sshpiperd example directory or Copy paste command below to run
go get github.com/tg123/sshpiper/sshpiperd && `go env GOPATH`/src/github.com/tg123/sshpiper/sshpiperd/example/showme.sh

the example script will setup a sshpiper server using

bitbucket -> [email protected]:22 # ssh 127.0.0.1 -p 2222 -l bitbucket
github -> [email protected]:22 # ssh 127.0.0.1 -p 2222 -l github
gitlab -> [email protected]:22 # ssh 127.0.0.1 -p 2222 -l gitlab

connect to gitlab

$ ssh 127.0.0.1 -p 2222 -l gitlab
Permission denied (publickey).

connect to github.com

$ ssh 127.0.0.1 -p 2222 -l github
Permission denied (publickey).

Configuration

sshpiper provides 3 pluginable components to highly customize your piper

sshpiperd daemon -h
to learn more

Upstream Driver (
--upstream-driver=
)

Upstream driver helps sshpiper to find which upstream host to connect and how to connect.

For example, you can change the username when connecting to upstream sshd by config upstream driver

Available Upstream Drivers

Database upstream driver connected to popular databases, such as mysql, pg or sqlite etc to provide upstream's information.

How to do public key authentication when using sshpiper

During SSH publickey auth, RFC 4252 Section 7, ssh client sign

session_id
and some other data using private key into a signature
sig
. This is for server to verify that the connection is from the client not
the man in the middle
.

However, sshpiper actually holds two ssh connection, and it is doing what

the man in the middle
does. the two ssh connections'
session_id
will never be the same, because they are hash of the shared secret. RFC 4253 Section 7.2.

To support publickey auth, sshpiper will modify the

sig
using a private key provided by upstream driver. e.g. (
id_rsa
) in the
workingdir/[username]/
.

How this work

+------------+        +------------------------+                       
|            |        |                        |                       
|   client   |        |   SSH Piper            |                       
|   PK_X     +-------->      |                 |                       
|            |        |      v                 |                       
|            |        |   Check PK_X           |                       
+------------+        |   in authorized_keys   |                       
                      |      |                 |                       
                      |      |                 |     +----------------+
                      |      v                 |     |                |
                      |   sign agian           |     |   server       |
                      |   using PK_Y  +-------------->   check PK_Y   |
                      |                        |     |                |
                      |                        |     |                |
                      +------------------------+     +----------------+

e.g.

on client

ssh-copy-id -i PK_X [email protected]

on ssh piper server

ln -s ~test/.ssh/authorized_keys workingdir/test/authorized_keys
ssh-keygen -N '' -f workingdir/test/id_rsa  # this is PK_Y
ssh-copy-id -i workingdir/test/id_rsa [email protected]

now

ssh [email protected] -i -i PK_X
, sshpiper will send
PK_Y
to server instead of
PK_X
.

Additional Challenge (
--challenger-driver=
)

sshpiper allows you to add your own challenge before dialing to the upstream. if a client failed in this challenge, connection will be closed. however, the client has to pass the upstream server's auth in order to establish the whole connection.

Additional Challenge
is required, but not enough.

This is useful when you want use publickey and something like google-authenticator together. OpenSSH do not support use publickey and other auth together.

Available Challengers

  • pam

Linux-PAM challenger

this module use the pam service called

sshpiperd

you can configure the rule at

/etc/pam.d/sshpiperd
  • azdevcode

Support Azure AD device code grant, More info

sshpier will ask user to login using webpage

   To sign in, use a web browser to open the page https://microsoft.com/devicelogin and enter the code ****** to authenticate.

Auditor for pipes (
--auditor-driver=
)

Auditor provides hook for messages transfered by SSH Piper which cloud log messages onto disks or filter some specific message on the fly.

Available Auditor

  • SSH Session logging (

    --auditor-driver=typescript-logger
    )

    When

    record_typescript
    is allowed, each piped connection would be recorded into typescript in
    --auditor-typescriptlogger-outputdir
    .

    The file format is compatible with scriptreplay(1)

    Example:

    $ ./sshpiperd daemon --auditor-driver=typescript-logger
    
    

    ssh [email protected] -p 2222 ... do some commands exit

    $ cd workingdir/user_name $ ls *.timing *.typescript 1472847798.timing 1472847798.typescript

    $ scriptreplay -t 1472847798.timing 1472847798.typescript # will replay the ssh session

Manage pipes with sshpiper command

SSH Piper comes with tools to list/add/remove pipes.

sshpiperd pipe -h
to learn more.

License

MIT

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