Secure Shell (SSH) is a protocol primarily for encrypted shell connections.
48
votes
14answers
6k views
Hundreds of failed ssh logins
Every night I get hundreds, sometimes thousands, of failed ssh logins on my RedHat 4 server. For firewall reasons from remote sites, I need to run on the standard port. Is there anything I should be ...
9
votes
5answers
10k views
Cygwin SSHd Autoblock Failed Logins
I'm running Cygwin with an SSH deamon on a Windows Server 2008 machine. I was looking at the Event Viewer and noticed as much as 5 to 6 failed login attempts per second (brute force) for the last week ...
130
votes
11answers
40k views
Can I nohup/screen an already-started process?
I'm doing some test-runs of long-running data migration scripts, over SSH. Let's say I start running a script around 4 PM; now, 6 PM rolls around, and I'm cursing myself for not doing this all in ...
61
votes
14answers
3k views
What's wrong with always being root?
I have a feeling this is a stupid question, but this is something I've wondered for awhile.
I have a VPS and this is my first big linux venture. I am the only person who has access to it. My question ...
24
votes
8answers
3k views
How do you setup ssh to authenticate using keys instead of a username / password?
How do you setup ssh to authenticate a user using keys instead of a username / password?
14
votes
5answers
9k views
How can I chroot ssh connections?
I would like to setup a chroot jail for most (not all) users logging in though SSH. I've heard it's possible with the latest versions of openssh, but I've not been able to find out how to do it. The ...
2
votes
4answers
414 views
ssh delay when connecting
When connecting to one specific server (running Debian Lenny) it always takes about 5 seconds before it prompts me to enter a password. After login there is no noticable delay anymore. There is also ...
5
votes
5answers
3k views
Is it worth the effort to block failed login attempts
Is it worthwhile running fail2ban, sshdfilter or similar tools, which blacklist IP addresses which attempt and fail to login?
I've seen it argued that this is security theatre on a "properly ...
86
votes
9answers
62k views
What is a good SSH server to use on Windows? [closed]
In my spare time I remotely support my wife's office via VPN into a Windows Server. I am about to purchase a wireless broadband service which doesn't support VPN.
I don't want to open up the remote ...
17
votes
7answers
5k views
How to configure a shortcut for an SSH connection through a SSH tunnel
My company production servers (FOO, BAR...) are located behind two gateway servers (A, B). In order to connect to server FOO, I have to open a ssh connection with server A or B with my username ...
37
votes
12answers
37k views
How to reconnect to a disconnected ssh session
Is there a way to connect to an ssh session that was disconnected? We are having problems with our network connection to a remote site that we are working on separately; however, in the mean time we ...
28
votes
2answers
28k views
SFTP logging: is there a way?
I'm wondering if there is a way to log commands received by the server. It can be all SSH commands, as long as it includes information on commands related to file transfer.
I'm having issues with an ...
13
votes
4answers
3k views
ssh tunneling only access
Is it possible to configure ssh (on linux) to allow access for tunneling only? Ie user can setup tunnels but cannot get a shell/access files?
38
votes
15answers
3k views
Preventing brute force attacks against ssh?
What tool or technique do you use to prevent brute force attacks against your ssh port. I noticed in my Security logs, that I have millions of attempts to login as various users through ssh.
This is ...
15
votes
8answers
10k views
What is a good modern parallel SSH tool?
I have heard that pssh and clusterssh are two popular ones, but I thought I would open it to discussion here and see what the community's experiences with these tools were? What are the gotchas? Any ...
18
votes
5answers
13k views
How to setup ssh's umask for all type of connections
I've been searching for a way to setup OpenSSH's umask to 0027 in a consistent way across all connection types.
By connection types I'm referring to:
sftp
scp
ssh hostname
ssh hostname program
...
27
votes
5answers
2k views
Smoothest workflow to handle SSH host verification errors?
This is a simple issue that we all face and probably resolve manually without giving much thought.
As servers change, are re-provisioned, or IP addresses reallocated, we receive the SSH host ...
10
votes
9answers
1k views
SSH to a computer that will then SSH to another computer [duplicate]
Possible Duplicate:
How to configure a shortcut for an SSH connection through a SSH tunnel
I have a situation where I would like to have SSH/SFTP access from my workstation to a server that ...
6
votes
4answers
1k views
How can I create a user only for sftp
I have added a user to the system via "adduser" script. Then, in the /etc/passwd file I tried changing the /bin/bash to /sbin/nologin or to /dev/null with no luck...
I would like the user not having ...
5
votes
2answers
462 views
SSH port forwarding
I want to connect to my computer(local) behind NAT through a public accessible server(public).
On local:
ssh -g -R 8000:localhost:22 user@public
Then on public:
ssh -p 8000 user@public
But I ...
2
votes
4answers
890 views
How to restore remote access to a RHEL system from expanded permissions set over the entire filesystem? [duplicate]
Cause of the problem
I intended to add group write permission on hidden files like '.hgignore' with the following:
# pwd
/opt
# sudo chmod -R g+w .*
The problem is that '..' matched this pattern, ...
7
votes
2answers
236 views
Special SSH Configuration
At the moment in my sshd_config I have it set so that passwords cannot be used and only keys can be used to login.
I need to enable passwords for one user. This user is yet to be created and has to ...
7
votes
5answers
20k views
SSH / SCP Server on Windows [duplicate]
Possible Duplicate:
What is a good SSH server to use on Windows?
Can anyone on the SF community recommend a trustworthy/easy to set up SCP server for windows. I do not want to go through ...
74
votes
9answers
9k views
Keeping a linux process running after I logout
I'm connecting to a linux machine through SSH, because I'm trying to run a heavy bash script that makes filesystem operations, and it's expected to keep running for hours. But I cannot leave the SSH ...
83
votes
22answers
6k views
How do you make it obvious you are on a production system?
A few of us at my company have root access on production servers. We are looking for a good way to make it exceedingly clear when we have ssh'd in.
A few ideas we have had are:
Bright red prompt
...
32
votes
5answers
5k views
Best system for managing ssh keys?
I've got several client computers (i.e. laptops, desktops, etc.), and I connect to several server machines that I manage, and I log into them all via SSH. I can imagine several schemes of managing ...
39
votes
6answers
13k views
sudo su - username while keeping ssh key forwarding
If I have a server A into which I can login with my ssh key and I have the ability to "sudo su - otheruser", I lose key forwarding, because the env variables are removed and the socket is only ...
85
votes
13answers
206k views
Why do I get “Permission denied (publickey)” when trying to SSH from local Ubuntu to a Amazon EC2 server?
I have an instance of an application running in the cloud on Amazon EC2 instance, and I need to connect it from my local Ubuntu. It works fine on one of local ubuntu and also laptop. I got message ...
77
votes
6answers
20k views
SSH keypair generation: RSA or DSA?
SSH supports two signature algorithms for key pairs: RSA and DSA. Which is preferred, if any? For RSA, what is the minimum acceptable key length?
34
votes
22answers
8k views
Why change default ssh port? [closed]
I've noticed that a lot of admins change the default ssh port.
Is there any rational reason to do so?
20
votes
7answers
50k views
How to automate SSH login with password?
How to automate SSH login with password?
I'm configuring my test VM, so heavy security is not considered. SSH chosen for acceptable security with minimal configuration.
ex)
echo password | ssh ...
47
votes
3answers
22k views
What's the difference between authorized_keys and authorized_keys2?
Just wanted a quick summary of the differences between them and why there are two?
Cheers
9
votes
5answers
18k views
How to put desired umask with SFTP?
I have a SFTP server (openssh/sftp-server) and I would like to set umask 002 for users using this service. I tried setting PAM (pam.d/common-session), and .profile for each user, but no luck.
With ...
5
votes
3answers
3k views
SSH relay server with OpenSSH
Is it possible to use OpenSSH to relay to other SSH enabled devices such as routers switches etc.. If is this something that can be done without creating a bespoke application on Linux to do it?
...
14
votes
7answers
9k views
Monitor an incoming SSH session in real time
Is there any linux software to monitor an incoming ssh session. At a previous job I was told that if you ever needed support from Red Hat for example you could have them SSH into your machine and you ...
5
votes
3answers
1k views
Is SSH logging capabilities equivalent to su logging for private/public key authentication?
Here at work, we have a non-root shared login account on UNIX that is used to admin a particular application. The policy is to not allow direct logins to the shared account; you must login as yourself ...
2
votes
2answers
1k views
Can't change assigned key pair on amazon ec2 instance
I can't seem to find the option to assign a newly created key pair to an amazon ec2 instance after deleting away the original key pair. I wanted to "deny" the first key pair from access to the ...
4
votes
15answers
3k views
Best way to mount a Linux filesystem on Windows over the Internet?
I was going to attempt Samba over SSH, any better ideas?
Edit:
My mom has been bugging me to do some offsite backing up of her files. She currently uses Norton Ghost. I have a VPS that I use for ...
7
votes
6answers
9k views
When IP aliasing how does the OS determine which IP address will be used as source for outbound TCP/IP connections?
I have a server running Ubuntu Server with four IP addresses aliased on a single NIC.
eth0 192.168.1.100
eth0:0 192.168.1.101
eth0:1 192.168.1.102
eth0:2 192.168.1.103
(Using ...
5
votes
1answer
2k views
No TTY present when running commands over SSH in here-document
I'm trying to run a command over SSH like this in a here-document:
ssh example.com <<END
sudo /etc/init.d/apache2 reload
END
Which normally works except when I'm trying to run something that ...
3
votes
3answers
2k views
root locked out of EC2
I was in the process of disabling root logins on an AWS EC2 instance. Right after setting PermitRootLogin no and restarting sshd, I closed the terminal on accident -- before setting up users with sudo ...
1
vote
5answers
1k views
SSH key exchange is not working
Is there any way to verify why SSH key exchange between 2 servers is not working?
In Server A:
I did the following steps:
ssh-keygen –t rsa
cd /.ssh
cp id_rsa.pub authorized_keys
Then in Server ...
3
votes
3answers
215 views
Block interactive SSH sessions while allowing certain commands
How would one only allow certain commands to be run via SSH and block interactive sessions?
rsync.net does this as well as bakop.com.
I.e. this would work:
ssh <user@host> mkdir test
scp ...
1
vote
1answer
65 views
SFTP user can't edit or create files
Server: Ubuntu 12.04 LTS
I am using openSSH and have created an SFTP user called bob who belongs to group sftponly. I have chrooted bob to his home directory which is /usr/share/nginx/www/bob/.
bob ...
17
votes
3answers
3k views
Centralized management system for SSH keys?
We are looking to switch to key-based management of SSH logins, and wonder if there any key-management systems which would allow us to centrally manage the access keys world-wide.
The system should ...
20
votes
2answers
11k views
What's best practice for communication between Amazon EC2 instances?
I've been setting up Amazon EC2 instances for an upcoming project. They are all micro instances, running Ubuntu Server 64bit. Here's what I've setup so far:
Web Server -- Apache
Database Server ...
23
votes
4answers
19k views
Can I automatically add a new host to known_hosts?
Here's my situation; I'm setting up a test harness that will, from a central client, launch a number of virtual machine instances and then execute commands on them via SSH. The virtual machines will ...
17
votes
5answers
4k views
How do I do Multihop SCP transfers?
I want to copy a file from my machine A to server C, but only have access to server C through server B.
Instead of first transferring to server B, log in and then transfer to server C, Is is possible ...
8
votes
5answers
9k views
Using SSH to remotely start a process
I have written a script that I am using to push and deploy a new service to several machines under my control, and in order to execute the process I am using ssh to remotely start the process. ...
20
votes
3answers
1k views
Does getting disconnected from an SSH session kill your programs?
So, say I get disconnected from an SSH-session after I've started rsync or cp or any other command that can be long running. Does that command keep running until it's finished after I get disconnected ...
