Questions about the OpenSSH implementation of the ssh protocol.

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2
votes
1answer
27 views

Arch Linux openSSH frequently drops connection

I'm running a VM using Oracle's VirtualBox. The OS is the latest version of Arch, 64-bit. For some odd reason, every so often (frequently enough to be very annoying and making it almost impossible ...
2
votes
1answer
882 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) ...
0
votes
1answer
29 views

SFTP Chroot and SSH

I have a chrooted SFTP user group to access my home server. The chroot location is /mnt/, mostly because it is already owned by root and is where I have mounted the external HDD I want to the chrooted ...
-1
votes
1answer
42 views

How to install openssh-server on openSUSE

I recently installed openSUSE, and I want to set up an ssh server so that I can ssh into this machine. However, I am having trouble installing openssh-server. I have tried $ sudo zypper install ...
2
votes
2answers
38 views

Chroot user exit jail [duplicate]

I am using OpenSSH chrootdirectory feature to give access to a user via ssh. Can this user exit the jail and return to the normal OS environment? Maybe with su?
1
vote
1answer
28 views

Integer after username in OpenSSH client separated by colon

I have a reverse SSH server in Cisco router(runs IOS operating system) and it listens on port 2001: C1841#sh control-plane host open-ports Active internet connections (servers and established) Prot ...
1
vote
2answers
642 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 ...
3
votes
2answers
1k views

Help updating OpenSSH to v6.6

My system is vulnerable to OpenSSH Wildcards on AcceptEnv Vulnerability, CVE-2014-2532. I have tried to update openssh to version 6.6 for centos but I can not get repository[sic] for that version. ...
15
votes
3answers
11k 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. ...
0
votes
1answer
43 views

Running 2 OpenVPN on the same box

(Fist of all, I'm a total Unix newbie). I know I can create two (or more) user accounts with root privileges, and I can access them independtly through SSH sessions. But I don't know how Unix systems ...
1
vote
1answer
34 views

Restrict SSH login to local network: VPN connection not allowed

There are two (unix) users who are allowed to connect to my Debian Wheezy server using ssh: git and peter. While git is allowed to connect from everywhere, peter (who is in the sudo group) should be ...
0
votes
1answer
33 views

Compiling LibSSH2 with specific LibSSL

I have downloaded and compiled the latest version of libssl, the result of which is located at /usr/local/ssl. I want to compile libssh2 using the files in this folder, and to do that I've set the ...
3
votes
3answers
488 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 ...
1
vote
2answers
60 views

SSH via cert-authority

I'm trying to use SSH using signed certificates. I'm using ssh -i keys/client.key to connect to the target device. If I generate a public key from that private key (with ssh-keygen -y -f ...
2
votes
2answers
65 views

RPM Says Shared Object Is Missing But I Can Find It With ls

Having a problem installing an openssh rpm I hand-rolled today: [root@local_host ]# rpm -i openssh-6.7p1-1.i386.rpm error: Failed dependencies: libcrypto.so.1.0.0 is needed by ...
0
votes
0answers
10 views

SSH tunneling error: “channel 1016:: open failed: administratively prohibited: open failed” [duplicate]

when I use config file in the /home/username/.ssh/config to connect to localhost with ssh, I get the following results: channel 1016: open failed: administratively prohibited: open failed channel ...
1
vote
0answers
63 views

openssh-server doesn't start in Docker container

I am having a weird problem. I am not able to ssh to docker container having ip address 172.17.0.61. I am getting following error: $ ssh 172.17.0.61 ssh: connect to host 172.17.0.61 port 22: ...
2
votes
0answers
21 views

Placing OpenSSH control socket in /run

OpenSSH has a feature that allows you to multiplex connections over a controlsocket. It is generally accepted that these control sockets should not reside in a common area, due to the security issues ...
0
votes
0answers
76 views

restrict ssh access to /bin and using bash as a shell

I want to restrict my admin user to /bin directory while permitting to use bash as a shell via ssh. This is in my sshd_config file: Match User admin ChrootDirectory /bin X11Forwarding no ...
1
vote
1answer
37 views

Can OpenSSH 6.7 optionally not depend on OpenSSL?

It has been reported on Slashdot on 2014-04-30 that OpenSSH now has a compile-time option to not depend on OpenSSL. However, OpenSSH 6.7 release notes, released on 2014-10-06, do not make any mention ...
6
votes
5answers
735 views

Use two different ip addresses per host in SSH

I have a server, named gamma, constantly up and running at work. Sometimes I connect to it from at home, in which case I use the public IP address 55.22.33.99. Sometimes, I connect to it when I'm at ...
3
votes
1answer
4k 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 ...
0
votes
2answers
38 views

downloading sshd logs from remote centos 7 server

When I log into a remote centos 7 server as root, I am able to see the sshd logs by typing journalctl _COMM=sshd in the terminal. But the logs are massive. How can I download all the logs into a ...
0
votes
0answers
89 views

SSH client connection not working to remote servers not working

I am unable to connect to other machines from one of my servers. Here is the verbose output (IP, domain, port are masked. OpenSSH version info removed): $ ssh -vvv user@example.com -p yyyy debug1: ...
0
votes
1answer
130 views

CentOS 7 VPN server

How do I set up a remote internet web server using CentOS 7 so that it is completely shielded by a VPN? Here is the use case: 1.) This means that ALL requests for ANY interaction with the web ...
0
votes
1answer
33 views

SSH connection gets lost, but not when logged in to MySQL

When I open an SSH connection to our database server and leave it open for a longer time, the connection gets lost at some point. I don't know why or how, but this happens a lot. I still see the ...
2
votes
1answer
32 views

Programatically / dynamically adjust SSH session port forwards

I have a workflow where I am trying to do the following: For a given existing SSH session, access the remote machinne and perform a process from which a port is returned (e.g. a remote daemon has ...
1
vote
1answer
103 views

restricting remote vpn login to ip address in CentOS 7

I have read that OpenSSH itself does not support authentication via specific IP address. In a CentOS 7 installation on a web server, how would one configure the login so that a user would not only ...
1
vote
2answers
173 views

SSH PC at office in local network from home

My office has one default gateway and behind that is a local network with locally assigned IP addresses to all computers including mine. I hold admin in my Ubuntu installed office PC and is it ...
2
votes
2answers
89 views

temporarily disable login using one specific ssh key

On my server, I have several public SSH keys in ~/.ssh/authorized_keys. I would like to temporarily block/disallow/deactivate one key. I want to prevent the user to log in using this key now. but I ...
2
votes
0answers
80 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 ...
0
votes
0answers
38 views

Cannot connect to OpenSSH when compiled with the gcc option: -finstrument-functions

I want to make custom traces of sshd. So, I have added the source file ptrace.c from here. This file enables to trace function calls (but this is not the subject of my question). So, I have modified ...
2
votes
1answer
120 views

update openssh and openssl on solaris

I got a nexenta system, I updated openssl to 1.0.1j, which I compiled from source code. I updated openssh to 6.7, from source code as well, and I get this: root@cteraportal:/root# openssl version ...
7
votes
2answers
367 views

Determine dynamically allocated port for OpenSSH RemoteForward

Question (TL;DR) When assigning ports dynamically for remote forwarding (a.k.a. -R option), how can a script on the remote machine (for instance sourced from .bashrc) determine which ports were ...
2
votes
1answer
248 views

public key authentication without authorized_keys file

I have a lot of ssh public key logins on a Linux server, e.g.: Jul 25 11:41:01 host sshd[24594]: Accepted publickey for root from xxx.xxx.xx.xx port 33374 ssh2 This is strange for me since there's ...
0
votes
1answer
147 views

Specifying a random monitoring port with autossh

I have many reverse ssh tunnels and because monitoring ports can't be reused, I am trying to find a free random port for monitoring. Meanwhile I specified -M 0 and the forwards work great and in ...
2
votes
1answer
194 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 ...
5
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 ...
0
votes
0answers
18 views

OpenSSH: UseDNS is not enforced

I cannot get the UseDNS constraint to work. It is set to UseDNS=yes on the server running sshd. That server queries a local DNS server which is the authority for each host on the network. Each host ...
1
vote
3answers
292 views

Can't ssh to a machine

All of a sudden, I couldn't ssh to a machine to which I used to ssh earlier. Consider I am ssh-ing from A to B. Output when I run ssh root@ip_addr_of_B I get: Permission denied ...
3
votes
1answer
167 views

How to know which public key was used when someone used passwordless ssh login?

Say for some reason, there is only a "user" account on a shhd server. Everyone has his own private key to ssh to the server, as "user". Then, is there a way to see who is he (during or after his ...
0
votes
0answers
74 views

Problem with OpenSSH

I think I got an OpenSSH-problem with my Ubuntu Server 14.04.1. Let me explain my setup: For development, I use Git and Gitolite. I have 3 server: server A ( master-server for git-mirroring) ...
4
votes
0answers
990 views

Can't figure out why ssh_exchange_identification: Connection closed by remote host appear

At home, I have setup a Raspberry Pi with the latest version of Raspbian and with ssh enabled. I also use a Mac Book Pro with OS X 10.9.3. I use ssh pi@192.168.0.22 to do some work on the Raspberry ...
0
votes
1answer
7k views

What is the default idle timeout for OpenSSH?

I can't seem to find an answer to this simple question, which I need for some compliance documentation. On a default install of CentOS 6.5 (OpenSSH 5.3p1-94.el6), after how long of being idle will ...
3
votes
1answer
246 views

Only apply Match keyword to single Host in ssh config

I have a host which I ssh into. Sometimes I'm inside the same network, and can ssh directly into it, other times I'm outside it and I need to use a proxy. Because ssh via the proxy server is much ...
28
votes
4answers
27k 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 ...)
22
votes
2answers
1k views

What's the purpose of the randomart image for user (not host) SSH keys?

The ssh-keygen generates the following output: The key fingerprint is: dd:e7:25:b3:e2:5b:d9:f0:25:28:9d:50:a2:c9:44:97 user@machine The key's randomart image is: +--[ RSA 2048]----+ | .o o.. ...
9
votes
3answers
2k views

Local, timestamped logging of all ssh commands?

How can I keep a local, timestamped record of all remote commands I use in ssh (command-line openssh client started through bash)? Requirements: Essential: 100% client-side without relying on ...
4
votes
2answers
426 views

Starting SSH server after VPN starts

I am running an OpenVPN server on Ubuntu 14.04 as well as OpenSSH. I have my SSH server configured to bind to an IP address on my VPN interface. Once my machine boots, binding to that IP fails. ...
1
vote
1answer
1k views

ssh_exchange_identification: Connection closed by remote host on vnx machine (linux)

I changed the password of my linux machine . I was able to login for sometime and after that I am not able to ssh. I am getting the following error: ssh es4042cs -v OpenSSH_5.1p1, OpenSSL ...