the secure shell (SSH) daemon

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2
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2answers
55 views

Allow SSH access but restrict root's access to a given set of IPs

I want to allow SSH for all users as normal except that I want to restrict root's access based on a set of IP addresses. So, users peter, paul, lary can login from anywhere, but root may login only ...
1
vote
2answers
34 views

Cannot login over ssh

I did something very stupid. I created user accounts on my linux server, then I disabled password logins. I configured ssh to not accept password logins and only accept ssh. I configured the ufw ...
0
votes
1answer
30 views

iptables and ssh

I'm running Arch Linux and I have a running SSH daemon to access my machine when I'm out side my LAN. I can do the connection, but iptables keeps blocking SSH Daemon, so I can only connect if I turn ...
0
votes
1answer
16 views

opensshd / openssh - allow EITHER keypair or password

I would like to configure my sshd to allow users to authenticate with a keypair, then fallback to password authentication. But I'm struggling to achieve that from the information in the man pages / ...
0
votes
1answer
32 views

Error becoming root centos

I'm getting the following error when I'm trying to become root -bash-4.1$ sudo su - Could not open a connection to your authentication agent. * Error: Problem adding; giving up I have tried eval ...
1
vote
2answers
20 views

Unexpected Match behavior in sshd_config

I'm trying to configure the following restrictions in my sshd_config: Users with local IP addresses face no restrictions Users with non-local IP addresses, who are in the sftp group, are allowed to ...
1
vote
1answer
29 views

Is 2s a “normal” variation in ssh's execution time?

In my program, ssh "normally" takes around 0.3s, however sometimes it may take more than 2s. I wonder whether this is a normal variation for ssh's execution time, and whether there is some thing I ...
3
votes
2answers
23 views

Can resource over-utilization actually cause users to be unable to SSH to Linux?

The night support guys where I work have a tendency to reboot machines citing the fact that they can't ssh in and figure out what's going on in the first place. It's pretty much against company ...
1
vote
0answers
21 views

Reverse AutoSSH working, but the proxied LISTEN ports fail randomly

I'm having a hard time describing the error, sorry for the lengthy explanation: I have a successful, working, stable reverse AutoSSH solution nailed up between a client beagle board and a server. The ...
2
votes
0answers
57 views

“Too many open files ssh” when the number of open files is far below ulimit

I was trying to set up 2000 concurrent ssh connections, but got the error message in server log (i.e. journalctl): sshd[1356]: error: reexec socketpair: Too many open files I've set both the soft ...
7
votes
1answer
145 views

Enable Massive Concurrent SSH to a single server

My goal is to allow 10000 concurrent sshs running on a single server. For simplicity I am ssh-ing to localhost: for i in `seq 1 10000`; do ssh localhost "echo ${i}; sleep 100" >>./info ...
2
votes
2answers
34 views

Is there a way to tell how a user authenticated their SSH connection ? i.e. whether it was by password or by public key?

I'm locking down my server to use public-key only. I just want to make sure before I flip the switch that all my users have already made the transition, and nobody is left using passwords to log in.
2
votes
1answer
22 views

Display full settings of sshd

The OpenSSH daemon has many "default" values for its settings. So looking at the sshd_config might not give someone the complete set of active settings. How to display the full sshd configuration ...
8
votes
1answer
164 views

Blocking SSH Brute Force attacks on IPv6

I recently had to work with some servers that have an IPv6 connection and I was surprised to find out that fail2ban does not have IPv6 support, neither does denyhosts. Searching on google I found that ...
0
votes
1answer
48 views

Configure ssh users under a group [closed]

I created a group called ssh_group and currently have nearly 20 users under AllowUsers in /etc/ssh/sshd_config. After I created the ssh_group, I modified the AllowGroups line like this AllowGroups ...
0
votes
1answer
36 views

Adding user override to sshd_config causes ssh_exchange_identification error

I wanted to allow SSH TCP forwarding for a specific user, so I added this section to sshd_config: Match User rainmannoodles AllowTcpForwarding yes TCPKeepAlive yes After that change, I get ...
0
votes
0answers
40 views

SMTP traffic being forwarded through SSH even do AllowTcpForwarding is disabled

I have a situation on one server, where it seems to be spaming over traffic being sent over SSH tunnel. Output below shows connections being made to remote SMTP server that seem to be initiated over ...
2
votes
1answer
24 views

Use two SSH ports, but open only one?

My iptables.conf looks loosely like this: -A INPUT -p tcp --dport 65000 -j ACCEPT -A INPUT -j DROP My sshd_config looks like this: Port 22 Port 65000 #AddressFamily any #ListenAddress 0.0.0.0 ...
2
votes
0answers
43 views

Two ISP and redirecting traffic

I have a gateway with two ISP connected to eth0 and eth2. There is also a eth1 with local network. I'm trying to group some services in one interface and some in the second: incoming traffic 1 ...
3
votes
3answers
170 views

How to start SSH daemon on boot on Linux Mint Debian v2

I'm using Linux Mint Debian v2, 64-bit. I noticed recently that my ssh daemon does not start automatically on boot. It used to. I'm not sure if it had to do with my UFW configuration or sshd_config ...
0
votes
0answers
96 views

xterm Xt error: Can't open display: localhost:11.0

I'm on a windows machine running Xming32, putty and plink. I have two centos boxes. One I can connect to just fine. The other I can't. I'm trying with this command plink -C -v jdearing@BROKENHOST ...
3
votes
1answer
57 views

sudo command inside heredoc block in a ssh session is not working

When i use heredoc and put all the commands inside heredoc as, ssh -t -i master.pem cloud-user@$1 <<EOSSH sudo service x restart sudo service y restart EOSSH it throws error as, ...
1
vote
1answer
94 views

How to ensure ssh via cgroups on centos?

When some cpu-intensive processes are running on the server, chances are that we could not log in to this machine with error 'operation timeout' via ssh command. According to this post answered by ...
1
vote
1answer
368 views

CentOS 7 - ssh login is refused when i use ssh public key, but only works with username password

I am not able to login via SSH key. I place my id_rsa.pub key in the /root/.ssh/authorized_keys [root@s .ssh]# ll total 4 -rw------- 1 root root 403 Jun 8 00:44 authorized_keys [root@s ~]# cat ...
2
votes
1answer
42 views

Is sshd_config TPCKeepAlive still using unencrypted channel and therefore vulnerable

This post from 2008 in ubuntuforums recommends disabling TCPKeepAlive Disable TCP KeepAlive messages. These messages are spoofable and are sent outside of the encrypted channel, and ...
4
votes
1answer
232 views

Uselogin in sshd_config

I was looking through my sshd_config file and I found this: #Uselogin no I know it's commented but there is no explanation above it and when I google it, I get this: Don't use the traditional ...
4
votes
5answers
128 views

Multiline Text Processing : Editing sshd_config

I have multiple blocks at the end of my sshd_config files like theses: Match User FOO ChrootDirectory /srv/www/FOO AllowTCPForwarding no X11Forwarding no ForceCommand internal-sftp ...
0
votes
1answer
62 views

Unable to login with SSH-RSA key

This post is following this question : Authentication refused: bad ownership or modes for file /var/git/.ssh/authorized_keys . The issue as exposed there is solved (about files modes of the ...
3
votes
3answers
996 views

Authentication refused: bad ownership or modes for file /var/git/.ssh/authorized_keys [duplicate]

EDIT The issue as exposed here is solved (about files modes of the .ssh folder. But an other issue persists so I create a new question : > Unable to login with SSH-RSA key I can no longer ...
2
votes
1answer
108 views

How to tell systemd to start sshd later in the boot sequence?

My sshd_config file specifies it should listen on some specific IP addresses instead of on all IP addresses. The problem is that one of these NICs doesn't come up until later in the boot sequence. ...
2
votes
1answer
48 views

Configure OpenSSH server not to require password *or* key for a particular user

For the purpose of a training session, I'd like to make it possible for a particular user to connect without requiring a password or key-based authentication. I do not know the IPs or other data of ...
2
votes
2answers
122 views

Passwordless login only works using directly invoked sshd on server

I've been through as many of the bugfixes as I can find for the classic ssh key issue : I've set up my public and private keys "correctly" but passwordless login still doesn't work. The details : ...
0
votes
0answers
61 views

fedora 21 workstation and sshguard 1.5 set up

I installed fedora 21 workstation, and I compiled and implemented sshguard 1.5 since I could not find rpm 64. How do I best set up sshguard so that it protects the server? Esp. in terms of reading the ...
0
votes
1answer
159 views

SSH login too slow in Centos 6.6 [closed]

SSH login take too much time in my CentOS machine, and also a ftp server is running on it. Please help me to speedup the login time for both root and ftp user. I tried some tricks but no ...
1
vote
1answer
92 views

Can't connect to the sshd in my unprivileged LXC guest. What to do?

So you configured your unprivileged LXC guest, by defining lxc.id_map = u 0 1000000000 10000 lxc.id_map = g 0 1000000000 10000 and of course assigning those subordinate UID/GID ranges to an ...
1
vote
1answer
158 views

Is there a canonical method to restrict ssh access to certain IP addresses in Unix?

I checked man pages related to ssh on OS X and other systems and tried using hosts.allow and hosts.deny files as per this post, and sshd_config to no avail. $ cat /etc/hosts.allow sshd: ...
2
votes
1answer
42 views

SSH demon not installed in linux embedded device

I have an embedded device which runs linux(arm). I am trying to update the executable through ethernet using scp command. But I got to know that sshd is not running in the device . I need to install ...
0
votes
0answers
51 views

How do I configure SSHd to require 2 (or more) passwords to log in

I'm asking because I want to setup a server that cannot be administered by any single admin, not without the permission (and oversight) of one other authorized admin (there can be many). Since there ...
0
votes
1answer
64 views

how to view failed login attempts?

I tried to view failed user login attempts since a specific time. But all methods I found by searching the internet does not work. I am using openSUSE 13.2. journalctl -a --no-pager ...
2
votes
1answer
86 views

How to make sshd listen to two ports, but restrict one of them to a single source address?

I need sshd to listen both on port 22225 (allowing connections on that port from any IP) and port 22 (allowing just a single static IP on that port). In other words, listen on two ports at the same ...
0
votes
0answers
50 views

ssh agent-forwarding with lxc

I have a "little" problem I try to ssh using putty and pageant to server, than to ssh into lxc-container and than to other server. But no publickey is used, it prompts for password (at last hop). ...
2
votes
1answer
221 views

How to use ssh over http or https?

I have a linux fedora21 client laptop behind a corporate firewall (which lets through http and https ports but not ssh 22) and I have a linux fedora21 server at home behind my own router. Browsing ...
0
votes
1answer
25 views

Set MasSessions to SSH does not take effect

I got a server with enabled ssh. To prevent attacks and to fit to my needs, I just need one connection at the same time to my server. So, I tried to set MaxSessions paramater to 1 in ...
1
vote
2answers
136 views

remote shell - are there any non-ssh based alternatives?

Are there any alternative SSH servers other than SSHD? One that is not SSH based? Ideally one that can be installed from offical Debian repository, that listens on a port other than port 22. (To ...
0
votes
1answer
3k views

How to open the SSH port 22? [closed]

I have installed the ssh utility on an embedded system but I can't connect to it. I am able to ssh from the device to another computer on the network but not the other way around. The only port ...
4
votes
1answer
428 views

Why did sshd delete my /dev/zero?

When I do lsof +c 0 | grep /dev/zero, I see the following two lines: sshd 19064 root DEL REG 0,4 497862 /dev/zero sshd 19064 root DEL REG 0,4 498725 /dev/zero ...
1
vote
1answer
164 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 ...
1
vote
1answer
179 views

SSH message, source of a after-login greeting command

On a server previously adminstered by someone else i noticed non-standard after-login ssh message. It looks like this: In case of problems please send an email to ....@..... Disk quotas for user ...
0
votes
2answers
281 views

SSH banner not showing

I have a fresh installation of OpenSSH. In the /etc/ssh/sshd_config I have the following entry: Banner /etc/issue.net I have restarted the SSH deamon using: sudo /etc/init.d/ssh restart. Now, ...
1
vote
2answers
261 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 ...