Questions about the OpenSSH implementation of the ssh protocol.

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27
votes
3answers
27k views

Restricting an SSH/SCP/SFTP user to a directory

Is there a simple way to restrict an SCP/SFTP user to a directory? All methods that I've come across require me to set a chroot jail up by copying binaries, but I don't think that should be necessary. ...
5
votes
2answers
203 views

Why are rules not combining in an ssh config file?

It seems like the following would work as expected, i.e., that the second rule, having a hostname that matches the first rule, would apply it. Host *.hostname.com User myuser IdentityFile ...
3
votes
2answers
3k views

check if latest openssh patch provided by RHEL is installed

We have encountered a security threat in one of our RHEL servers which says the SSH server is configured to use Cipher Block Chaining. As far as I know, the RHEL systems provide security updates ...
15
votes
3answers
12k views

What difference between openssh key and putty key?

I've found ssh-keygen ("ssh" package) comand produce another keys that puttygen command ("putty" package). If I create public and private keys with ssh-keygen some ssh-servers can not accept my keys. ...
8
votes
3answers
17k views

ssh, start a specific shell, and run a command on the remote machine?

I am in a situation where several users are sharing the same user account on a remote machine. I have a "personal" directory where I wrote my own .zshrc file, and I would like to have a way to: ...
3
votes
1answer
6k views

installing fail2ban on CentOS 7

I am using @GarethTheRed 's answer to this question to install fail2ban on a remote CentOS 7 server. I am able to complete all the steps up until tail -f /var/log/fail2ban.log, at which point I get ...
2
votes
1answer
210 views

Is there a way to run a privileged command upon successful SSH login (not necessarily with shell or PTY)?

I'd like to run a privileged command upon successful SSH logins at the server's end. However, this has to be in the server configuration (sshd_config or anything else that cannot be manipulated or ...
0
votes
1answer
371 views

Simple jail for user with open-ssh [duplicate]

Possible Duplicate: Restricting an SSH/SCP/SFTP user to a directory Can I confine my users to their /home/%u directory using simply open-ssh configuration? I did the following from what I ...
11
votes
2answers
27k views

SSH key-based authentication: known_hosts vs authorized_keys

I read about setting up ssh keys in Linux and have some questions. Correct me if I'm wrong… Let's say host tr-lgto wants to connect to host tr-mdm using ssh. If we want to be sure that it's the real ...
29
votes
4answers
28k views

What is the point of sshd “UseDNS” option?

I know what it does, but i don't know why. What attack(s) does it prevent ? Is it relevant for all kind of authentication methods ? (hostbased, password, publickey, keyboard-interactive ...)
5
votes
2answers
2k views

Can ssh_config's ProxyCommand run a local command before connecting to a remote machine?

Before I can to connect to a particular remote machine I have to run a certain local command. So instead of ssh me@remote.machine I have to do local_command ssh me@remote.machine I would like to ...
4
votes
2answers
241 views

SSH - How to make X applications run on client?

I have the reverse problem that most people seem to be having. If I start an X application while logged into ssh, it displays on the server(host) machine instead of the client(local). This is the ...
3
votes
1answer
603 views

Disable ForwardX11Timeout without ForwardX11Trusted in OpenSSH Client?

By default, recent versions of OpenSSH automatically set ForwardX11Timeout to 20 minutes if you set ForwardX11Trusted to no. This means that 20 minutes after you start your ssh connection, you can't ...
5
votes
3answers
25k views

Where are my sshd logs?

I can't find my sshd logs in the standard places. What I've tried: Not in /var/log/auth.log Not in /var/log/secure Did a system search for 'auth.log' and found nothing I've set /etc/ssh/sshd_config ...
3
votes
1answer
2k views

how to connect ssh 'with' specified port?

I know how to connect 'to' a certain port when ssh'ing. ssh user@remotehostip -p XXX but is there a way to establish a ssh 'with' a certain port? I mean, is there a way to specify the port which ...
1
vote
2answers
712 views

Intermittent 'ssh_exchange_identification: Connection closed by remote host' error

While there are many questions on this site and others addressing this very issue, I haven't yet found one that seems to address what I'm experiencing. When trying to ssh a linux box from a MBpro ...
5
votes
2answers
4k views

sshd process inoperative

I have an AIX server which suddenly stopped servicing SSH connections. When I try to start the service through startsrc -s sshd it says: 0513-059 The sshd Subsystem has been started. Subsystem PID is ...
4
votes
1answer
96 views

how to escape “\”in ssh-copy-id?

I'm connected to Ubuntu server that is a member of a corporate Active Directory domain via likewise-open. The users are in the form mydomain\myuser. I can connect to it via ssh, escaping the \ with ...
3
votes
2answers
325 views

Why doesn't the ssh command follow RFC on URI?

The RFC: Uniform Resource Identifier (URI) Scheme for Secure File Transfer Protocol (SFTP) and Secure Shell (SSH) presents the SSH URI as: ssh://[<user>[;fingerprint=<host-key ...
2
votes
0answers
89 views

How to find out what triggers ssh-askpass prompting for passphrase periodically

I recently deleted the contents of my ~/.ssh directory and generated new keys. They new ones work fine, but every once in a while I am getting a gui dialog titled OpenSHH from asking for the ...
2
votes
1answer
986 views

ssh-add -D doesn't erase stored keys from the ssh-agent

How come this happens?: stan@tcpc:~/.ssh$ ssh-add -l 8192 e0:45:5e:cc:45:3e:17:2b:a6:54:6f:8d:53:1b:j2:e3 github (RSA) 2048 25:41:53:a6:45:5d:ac:eb:5c:45:f8:ce:42:a9:he:aa BITBUCKET (RSA) ...
2
votes
2answers
2k views

OpenSSH, chroot user: Root needs to own the user directory, is there any consequence?

I want to create an account for my friend on my computer, but I don't want my friend to be able to view all my files. I saw that with OpenSSH, there is an option for that. Inside the SSHD ...
0
votes
1answer
778 views

Double port forwarding - SSH

NOTE: I'm not explaining why I want to do this. But here is the requirement. There are 4 hosts. Host A, Host B, Host C, Host D Host A is running some application which can be accessed at port 8001 ...