matir / sshdog

Small portable SSH server in Go.

SSHDog

SSHDog is your go-anywhere lightweight SSH server. Written in Go, it aims to be a portable SSH server that you can drop on a system and use for remote access without any additional configuration.

Useful for:

• Tech support
• Backup SSHD
• Authenticated remote bind shells

Supported features:

• Windows & Linux
• Configure port, host key, authorized keys
• Pubkey authentication (no passwords)
• Port forwarding
• SCP (but no SFTP support)

Example usage:

% go build .
% ssh-keygen -t rsa -b 2048 -N '' -f config/ssh_host_rsa_key
% echo 2222 > config/port
% cp ~/.ssh/id_rsa.pub config/authorized_keys
% rice append --exec sshdog
% ./sshdog
[DEBUG] Adding hostkey file: ssh_host_rsa_key
[DEBUG] Adding authorized_keys.
[DEBUG] Listening on :2222
[DEBUG] Waiting for shutdown.
[DEBUG] select...

Author: David Tomaschik [email protected]

This is not a Google product, merely code that happens to be owned by Google.

sshdog's Issues

have errors

./sshdog 
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x5c9a46]

goroutine 1 [running]:
debug/elf.(*Section).ReadAt(0xc0001c2000?, {0xc0001cc000?, 0x270?, 0x24?}, 0x40?)
	<autogenerated>:1 +0x26
archive/zip.readDirectoryEnd({0x6c79c0, 0xc000164d00}, 0x210)
	/usr/local/go/src/archive/zip/reader.go:526 +0xf5
archive/zip.(*Reader).init(0xc000150a10, {0x6c79c0?, 0xc000164d00}, 0x210)
	/usr/local/go/src/archive/zip/reader.go:97 +0x5c
archive/zip.NewReader({0x6c79c0, 0xc000164d00}, 0x210)
	/usr/local/go/src/archive/zip/reader.go:90 +0x5e
github.com/daaku/go%2ezipexe.zipExeReaderElf({0x6c7de0?, 0xc000014048}, 0x60e369)
	/root/go/pkg/mod/github.com/daaku/[email protected]/zipexe.go:128 +0x8b
github.com/daaku/go%2ezipexe.NewReader({0x6c7de0, 0xc000014048}, 0x0?)
	/root/go/pkg/mod/github.com/daaku/[email protected]/zipexe.go:48 +0x98
github.com/daaku/go%2ezipexe.OpenCloser({0xc00001e6f0?, 0xc000119d10?})
	/root/go/pkg/mod/github.com/daaku/[email protected]/zipexe.go:30 +0x57
github.com/GeertJohan/go%2erice.init.0()
	/root/go/pkg/mod/github.com/!geert!johan/[email protected]/appended.go:42 +0x65

Need an 'if (!windows)' check around pty allocation.

Running sshdog on Windows causes messages like this in the log:

[DEBUG] Failed allocating pty: Unsupported platform

Since it is Windows, and that will never work, it would be better to skip the pty allocation altogether in that case.

Haven't looked at the source, yet. Just saw this today.

Example usage has unnecessary invocation of rice.

Example usage text includes this line:

% rice append --exec sshdog

However, if that is done, get this output

no calls to rice.FindBox() or rice.MustFindBox() found in import path github.com/Matir/sshdog

So it is a no-op.

Race condition in SCP errors

SCP errors are not delivered consistently. This might be a race in closing the channel before the message is delivered?