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Top Forums Shell Programming and Scripting Are free public shells for ssh tunneling safe? Post 302468105 by Neo on Monday 1st of November 2010 04:15:47 PM
Old 11-01-2010
Quote:
Originally Posted by rafunk
To clarify, by public shell I meant a shell for which you can sign up on certain websites for free. You signup and then you can use your personal login and password to access the shell.
I understood exactly what you mean by a free shell account.

On these accounts, you don't have superuser permissions and you did not install and compile sshd yourself. This means you don't know what sshd is doing.

In addition, when you set up an ssh connection between your client and the free shell server, only the connection is secure between the end points of the sockets.

This means that the superuser on the free server could, in theory, log and read your messages, if they wanted to with a simple code mod.

If you want "security" you need to have control over the "box in the middle" or you will be subject to a variation of what is called "the man in the middle attack".

Of course "secure" is relative, and if you don't care if the superuser on the free shell server can track your web surfing, then ...... it does not matter. I simply answered your question correctly, that it is not "secure" to use a third party server that you don't have superuser privs on the box.
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GIT-SHELL(1)							    Git Manual							      GIT-SHELL(1)

NAME
git-shell - Restricted login shell for Git-only SSH access SYNOPSIS
chsh -s $(command -v git-shell) <user> git clone <user>@localhost:/path/to/repo.git ssh <user>@localhost DESCRIPTION
This is a login shell for SSH accounts to provide restricted Git access. It permits execution only of server-side Git commands implementing the pull/push functionality, plus custom commands present in a subdirectory named git-shell-commands in the user's home directory. COMMANDS
git shell accepts the following commands after the -c option: git receive-pack <argument>, git upload-pack <argument>, git upload-archive <argument> Call the corresponding server-side command to support the client's git push, git fetch, or git archive --remote request. cvs server Imitate a CVS server. See git-cvsserver(1). If a ~/git-shell-commands directory is present, git shell will also handle other, custom commands by running "git-shell-commands/<command> <arguments>" from the user's home directory. INTERACTIVE USE
By default, the commands above can be executed only with the -c option; the shell is not interactive. If a ~/git-shell-commands directory is present, git shell can also be run interactively (with no arguments). If a help command is present in the git-shell-commands directory, it is run to provide the user with an overview of allowed actions. Then a "git> " prompt is presented at which one can enter any of the commands from the git-shell-commands directory, or exit to close the connection. Generally this mode is used as an administrative interface to allow users to list repositories they have access to, create, delete, or rename repositories, or change repository descriptions and permissions. If a no-interactive-login command exists, then it is run and the interactive shell is aborted. EXAMPLE
To disable interactive logins, displaying a greeting instead: + $ chsh -s /usr/bin/git-shell $ mkdir $HOME/git-shell-commands $ cat >$HOME/git-shell-commands/no-interactive-login <<EOF #!/bin/sh printf '%s ' "Hi $USER! You've successfully authenticated, but I do not" printf '%s ' "provide interactive shell access." exit 128 EOF $ chmod +x $HOME/git-shell-commands/no-interactive-login SEE ALSO
ssh(1), git-daemon(1), contrib/git-shell-commands/README GIT
Part of the git(1) suite Git 1.8.5.3 01/14/2014 GIT-SHELL(1)
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