Questions about the OpenSSH implementation of the ssh protocol.

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2
votes
2answers
384 views

Unable to force passphraseless ssh authentication while port forwarding

I'm completely at a loss as to what is preventing my local machine from authenticating the connection that is being forwarded from the remote server. I've read a ton of the posts on here regarding ...
3
votes
1answer
88 views

What are all of the SSH Key files?

There are six key files in /etc/ssh directory for private and public keys. 4 of them are for DSA and RSA public & private keys. but there are two more files named ssh_host_key and ...
1
vote
1answer
227 views

How to prevent ssh-agent from starting in CentOS?

How do I stop ssh-agent from starting when logging into CentOS via openssh? There are no references to ssh-agent in my bash startup scripts (.bashrc) or /etc/bashrc.
3
votes
2answers
370 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 ...
5
votes
1answer
122 views

Can an OpenSSH server forward inbound traffic to another server?

In my current work setup, I have: Windows 7 laptop Ubuntu virtual host / SSH Windows 2k8 guest I'd like to be able to RDP from my laptop into the Windows guest without having to open additional ...
16
votes
3answers
14k views

What difference between openssh key and putty key?

I've found that ssh-keygen ("ssh" package) produces different keys from puttygen ("putty" package). If I create public and private keys with ssh-keygen some ssh-servers will not accept my keys. If I ...
3
votes
1answer
1k 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) ...
12
votes
5answers
854 views

what's the purpose of ssh-agent?

I've read the official definition: ssh-agent is a program to hold private keys used for public key authentication (RSA, DSA, ECDSA). The idea is that ssh-agent is started in the beginning of an ...
0
votes
1answer
81 views

ssh private key stops accepting my passphrase

When booting my laptop today I found that ssh (openssh) simply refuses to accept my passphrase when reading my private key. My only idea of how that could've happened is if the HDD has somehow ...
2
votes
1answer
114 views

Assuming sshd allows only public key authentication, how do I log the fingerprints?

With OpenSSH, how can I log the fingerprints of the keys used for authentication? I would like to log it in production, so it would be best if this wasn't just some debug setting or similar.
0
votes
1answer
973 views

non root ssh keys help

I'm having issues setting up a different CentOS account with its own pair of SSH keys. I have created the required files but when connecting with Putty it says Connection refused, here's the putty ...
18
votes
1answer
12k views

OpenSSH: How to end a match block

I'm using a Match block in OpenSSH's /etc/ssh/sshd_config (on debian) to restrict some users to SFTP: # my stuff Match group sftponly X11Forwarding no AllowTcpForwarding no ForceCommand ...
7
votes
3answers
448 views

OpenSSH - map aliases in ~/.ssh/config to IP addresses in command line

Is it possible to query ~/.ssh/config in the command line? Let's say I would like to retrieve what IP address does the particular alias point to in a separate program, is it possible?
2
votes
0answers
357 views

Making ChrootDirectory directory writable by SFTP user

If a user logs into a machine via SFTP, one can make use of ChrootDirectory keyword to give an illusion that user is in a root directory. But that directory is only writable by root user. I would love ...
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
98 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 ...
31
votes
4answers
30k 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 ...)
3
votes
3answers
2k views

How to limit ssh access for localhost only?

I need to forbid ssh access (except localhost) for specified user. So. ssh localhost should work. ssh hostname from outside should not work for that user. All other users should work as usual.
2
votes
2answers
1k views

SSH public key login: two different keys and SSH_AUTH_SOCK behaviour

A user (user1) on an Ubuntu 12.04 desktop has two SSH RSA keys configured: ~/.ssh/id_rsa and ~/.ssh/id_rsa1 (and .pub files). Both public keys are configured in the authorised keys on the server's ...
0
votes
1answer
388 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 ...
5
votes
1answer
683 views

Avoiding duplicate entries in ~/.ssh/known_hosts

I have my DNS search path set to ".intranet", ie, /etc/resolv.conf contains: search intranet When I SSH to a host using a FQDN, like "mailserver.intranet", it adds an entry for ...
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 ...
1
vote
3answers
1k views

Can directory listing be disabled for sftp?

A question arose in a group discussion: Can directory listing be disabled for sftp while still retaining read and write access? We are using openssh on ubuntu server 11.02 if that helps.
12
votes
2answers
32k 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 ...
3
votes
3answers
3k views

SSH connection freezes after bigger output when inactive for a while

I have a problem with an SSH session freezing after using it again when it was idle for a while. The problem is that the session doesn't freeze immediately, I can still use it. But as soon as a ...
5
votes
1answer
734 views

Public Key Auth + Kerberos

I've setup public key authentication for ssh'ing into my university machine. However, it only logs me in on the local machine and doesn't give me Kerberos credentials which I need for accessing my ...
6
votes
5answers
1k views

ssh command unexpectedly continues on other system after ssh terminates

I'm running the below command, and monitoring the output file on the other system: ssh $ip_address 'for n in 1 2 3 4 5; do sleep 10; echo $n >>/tmp/count; done' If I kill the ssh command ...
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 ...
2
votes
3answers
3k views

Can't SSH into Any Server

I work on remote servers frequently, but for some reason I cannot discern, today I am unable to ssh into anything. Everything comes back with Write failed: broken pipe. I know this is a common ...
7
votes
1answer
3k views

how to set the sftp -s subsystem option in a configuration file

The sftp command supports a subsystem option (-s) which allows the remote user to select the remote sftp-server executable, and optionally upgrade to sudo in the process like so; sftp -s ...
3
votes
1answer
880 views

How to setup port redirection after a ssh connection has been opened?

I'm using openssh on both client and server. I know I can run ssh -L or ssh -R to setup some port redirections over ssh. However, since they are command-line parameters, such redirections must be ...
16
votes
3answers
23k views

How do I convert a ssh-keygen public key into a format that openssl PEM_read_bio_RSA_PUBKEY() function will consume?

I'm having an issue generating a public key that the openssl PEM_read_bio_RSA_PUBKEY() function can consume. I keep getting errors. Obviously I cannot simply use the ASCII string in the ssh-keygen ...
3
votes
1answer
834 views

List ports tunnelled on OpenSSH server

Is there any way to list the tunnels that SSH clients connected to my OpenSSH server have set up? I can use e.g. lsof -i to show connections that are being actively tunnelled, but I'd like to be able ...
3
votes
3answers
494 views

How to install openssh in Crux Linux

In Crux Linux I already have installed SSH but when I use ssh-keygen, and try to use the command: ssh localhost to test SSH I get this error: # ssh localhost ssh: connect to host localhost port ...
3
votes
3answers
25k views

How to ssh to remote server using a private key?

I have two servers. Both servers are in CentOS 5.6. I want to SSH from Server 1 to Server 2 using a private key I have (OpenSSH SSH-2 Private Key). I don't know how to do it over unix. But what I did ...
11
votes
1answer
5k views

Limits of SSH multiplexing

I have the following entry in my .ssh/config file Host AAA User BBB HostName CCC ControlMaster auto ControlPath ~/.ssh/%r@%h:%p The above allows me to multiplex multiple ssh ...
2
votes
1answer
180 views

Wrapping socket connections

I'd like to wrap an insecure connection (this one: http://culturedcode.com/things/) with a secure tunnel, a bit like http://en.wikipedia.org/wiki/Stunnel does, just using UNIX tools. What's the best ...
8
votes
3answers
19k 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

Can ping but can't do ssh

I am able to ping my friend but not able to do ssh. Why so? He is using a modem. I thought there might be some firewall enabled. I told him to type #iptables -F He did that, but still I am not able ...
0
votes
1answer
431 views

Does OpenSSH_5.9p1 support Chrooted SSH?

Lately i upgraded my SSH server with OpenSSH_5.9p1 and tried to setup chrooted SFTP/SSH. So far i managed to setup chrooted access only for SFTP using new feature of openssh5.9p1: Match User ...
6
votes
4answers
550 views

SSH “sleeping” for a long time before connect? [duplicate]

Possible Duplicate: How to speed my too-slow ssh login? I have a very strange issue with my SSH server. Whenever I attempt to connect, it literally waits about 30 seconds to a minute before ...
4
votes
1answer
992 views

Use different authentication methods for OpenSSH server depending on client IP

I'm sure this has been answered before, but I could not locate the answer with Google, and this search. I currently only allow shared key authentication for openssh server on my box. However, I ...
6
votes
1answer
1k views

All about ssh ProxyCommand

I am looking for an in-depth explanation of the following ProxyCommand, down to the nuts and bolts of its operation, please. Can you kindly completely dissect it for me and improve on it if you can? ...
3
votes
5answers
17k views

ssh server: reasons for sudden “Connection closed by remote host”

One of my ec2 servers has stopped receiving ssh connections. The OS is Ubuntu server 8.04, and the ssh server is the standard openssh-server. After months of uptime, I tried to connet to it today, ...
4
votes
3answers
765 views

Is there a way to run an ssh server on an Android device?

I'm looking to install Debian over my Android installation so as to be able to use openssh-server, as it's so much better than Dropbear. Is there an easy way to do this, or just to simply install ...
6
votes
2answers
7k views

Multiple 'Host *' in ssh_config?

My understanding of the way ~/.ssh/config works is that each 'Host ' line takes effect for any host matching after that point in the config file. I have a number of personal servers and work servers ...
0
votes
1answer
730 views

github ssh problem- permission denied(publickey)

I tried setting up git as shown in Github's help page, on Arch linux but there seems to be some problem with the SSH keys. It gives this error- Permission denied (publickey). This problem is ...
6
votes
2answers
1k views

Should I be backing up my SSH host keys?

In my automated backups, I'm not sure if I should be doing this. If the hard drive fails or if I wipe the hard disk and start over, what will be the effect of starting with a new SSH host key to my ...
3
votes
2answers
3k views

SSH slow at starting session

Starting an Interactive shell over SSH is slow to one of my servers. Everything leading up to it including negotiating encryption is fast, but then it hangs for 45 seconds. After that, it finishes ...
28
votes
3answers
31k 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. ...