2
votes
2answers
73 views

Why is it said that SSH key authentication is less vulnerable than ssh password authentication when SSH is exploitable?

I'm not asking about password vs key authentication. I've seen a few times (and even Amazons AWS) says that even if SSH has a major vulnerability that key authentication would make such an exploit ...
1
vote
3answers
88 views

Why does SSH have unsecure defaults?

Why does SSH come with such an unsecure default configuration? to name what I consider unsecure defaults: root login enabled on SSH SSH protocol version 1 (which is vulnerable to MIM attacks) ...
0
votes
2answers
37 views

which unix or linux command is used to change root password of remote machine(Just an IP address) without using SSH Login [closed]

which unix or linux command is used to change root password of remote machine(Just an IP address)? Suppose I just have an IP address of the target machine which is on my network, But I do not know ...
1
vote
1answer
44 views

Security for a web server for multiple people?

I have an apache web server set up where multiple people have their websites hosted, mostly php based websites. The problem is, when these people upload their website files, it has read permissions ...
5
votes
2answers
169 views

Writing a “telnet server” type program that uses SSH instead of telnet

So people have written server programs using telnet in which the user simply does telnet server.com and this connects them to the server program, which then provides them with a textual program they ...
1
vote
1answer
254 views

How to Block SSH Brute Force via Iptables and How does it work?

I'm planning to add the following rules to iptables to stop ssh brute force attack which are common these days. -A INPUT -i eth0.103 -p tcp -m tcp --dport 4522 -m state --state NEW -m recent --set ...
2
votes
1answer
145 views

Was my Unix server compromised?

Someone asked if this constituted a break-in and wondered if their server had been compromised. Jan 12 04:16:51 foo sshd[26725]: Failed password for root from 61.174.51.207 port 1076 ssh2 Jan 12 ...
5
votes
1answer
96 views

Secure access to remote SSH tunnel

So I wish to be able to access my Raspberry Pi (which I keep at home behind a firewall) remotely. One option is to use a static IP address, but as a poor student I don't want to fork out for one, and ...
3
votes
2answers
112 views

SSH when to use public key and password?

I think I understand the difference between Public Key authentication and Password. But how do I decide which one to use and which one is most secure in what situation? Can anybody give me some real ...
0
votes
0answers
40 views

Prevent scp from asking passphrase [duplicate]

I have enabled private key based access to my server. I have generated the certificates with a passphrase. So to ssh to that machine I have to do - $ ssh -i .ssh/id_rsa_server foo@example.com and ...
0
votes
2answers
112 views

SSH authentication by public key and password in the same time

Something is not clear to me with SSH authentication. I have a Talend job which connects to sFTP (using SSH protocol) and on the property page of the component, I have the choice between: 1. ...
2
votes
3answers
170 views

What happens if I delete all user passwords?

I have a Fedora VPS with a root user that has no password. I login with SSH keys. I had another, less privileged account on that server, used for web administration. I've now deleted its password ...
4
votes
1answer
51 views

TCP wrapper “except” option

I configured the /etc/hosts.allow at the machine 192.168.122.50 with the following option. sshd : ALL EXCEPT 192.168.122.1 and tried ssh root@192.168.122.50 from the machine 192.168.122.1 and I was ...
3
votes
2answers
288 views

how to know the type of symmetric encryption used by ssh?

I want to know the type of symmetric encryption (after authentication) used by ssh in a connection client-server. I'm not sure who determines the encryption. Client or Server?. I have looked in ...
2
votes
2answers
110 views

Securely allowing users to create accounts

1) I'm struggling to find a secure way to allow new users to create accounts without granting them admin rights to do so. If you already have an account on my system and can work UNIX command line, ...
2
votes
3answers
2k views

Why do I get error “Could not chdir to home directory”

I work in support, and occasionally I'm given shell access to a remote Linux system. I frequently find that when the admin gives me remote access, that I get the following output upon login. ...
28
votes
4answers
3k views

Why is root login via SSH so bad that everyone advises to disable it?

Everybody on the Internet advises to disable root login via SSH as it is a bad practice and a security hole in the system, but nobody explains why it is so. What is so dangerous in enabling root ...
1
vote
2answers
130 views

How to check which SSH keys are currently 'active'?

How might one check which .rsa, .pem, and other files are 'loaded' or 'active' by ssh-add? I just had this scare: $ scp -i /home/dotancohen/.ssh/dotancohen.pem someUser@1.2.3.4:~/files.tgz . Warning: ...
-1
votes
1answer
306 views

SSH key based login bypasses password policies

I noticed that logins via an SSH key bypass the LDAP password policies (password ageing, password warning, and password lockout due to failed attempts, etc). Is there any way to force key-based ssh ...
5
votes
7answers
298 views

Are there additional ways to protect SSH connections besides firewall and RSA Keys?

Sometimes I don't have a static IP and need to administrate my web server remotely. I'm looking for any additional layers of protection I could add to make opening port 22 safer. Currently I have ...
2
votes
3answers
210 views

denyhosts is blocking existing users from logging in from unknown (new) IP addresses

I have denyhosts set up and working on Ubuntu 12.04. It apparently works well, except it is too strict. I can log in from any IP address that I have added to hosts.allow in advance. My sshd_config ...
1
vote
0answers
87 views

Reverse ssh-agent forwarding and unlocking remote keys with your local keys

So the following two things should both be possible to do with ssh the question is just how difficult they would be and I'm hoping someone can give me an easy answer. 1) Suppose I have several ...
0
votes
1answer
120 views

Iptable rule to ssh over the internet

I've a server abc.example.com and a remote desktop zzz.example.com. I'm using SSH over a custom port, say, 6789. Whenever my firewall is off, I'm able to connect to the server successfully. But, as ...
6
votes
1answer
193 views

Does fail2ban offer any additional protection to SSH if password login is already turned off?

I’m setting up a Debian VPS on Linode to use as a public web server, and I’m following their security suggestions. The last suggestion they make is to install fail2ban, to avoid dictionary attacks on ...
2
votes
1answer
66 views

How can I use ForwardAgent with keychain, or detect a new login?

My scenario: I have Server A at home, and Server B at my parents house. I also have Laptop A and Laptop B at home. I do all sorts of strange ssh hops - I might connect Laptop A -> Server A -> ...
1
vote
1answer
152 views

Having the 'id_rsa.pub' file in my dotfiles public repo securely

So this is something that I'm wondering, how can I have this file in my dotfiles GitHub repo? I'm sick and tired of having to generate a new SSH key every time I'm on a new computer or re-install my ...
6
votes
2answers
278 views

ssh-agent: don't forward authentication for the whole keyring

I have two private ssh keys : one to access my personnal machines, one to access servers at my job. I add those two keys to my ssh-agent with ssh-add. Now, when I do ssh -A root@jobsrv I ...
1
vote
5answers
1k views

How to securely automate running commands as root with “sudo su -”?

hint (on client side, how to encrypt files/pwd's): # encrypt pwd with ssh key: openssl rsa -in ~/.ssh/id_rsa -outform pem > ~/.ssh/TEMP-id_rsa.pem 2>/dev/null openssl rsa -in ~/.ssh/id_rsa ...
0
votes
1answer
35 views

How to identify which application is trying to access the unixbuild server?

The error message I am seeing is: Failed publickey for raj from 10.*.*.** port 34355 ssh2 Mar 18 05:22:34 unixbuild sshd[16956]: [ID 1000034 auth.info] Failed password for raj from 10.*.*.* port ...
2
votes
1answer
97 views

Configure SSH keys for production and DR server

Here is the case, we have successfully configured SSH keys (and hence password-less SFTP connection) between ProdServer-A to ProdServer-B. It works, or so I thought still yesterday. Yesterday ...
1
vote
1answer
70 views

Change order of Private Keys passed via SSH login

ssh -i ~/.ssh/username username@xx.xx.xx.xxx -v Server is set to accept only 3 log on tries. The ssh system is trying 3 identity files before attempting the correct identity file. debug2: key: ...
1
vote
2answers
89 views

how to require sudo to view files?

I have a ssh server. I allow people to connect to it if they want. I do my programming homework on it. I am in trouble with my teacher because people were cheating off it. I need to know how to ...
3
votes
1answer
312 views

What should I check after an unauthorized access?

I accidentally left an open port on my router, leaving access to one of my computers via SSH, using a rather insecure password. I noticed because I checked /var/log/auth.log and there is just one ...
7
votes
1answer
323 views

How can I limit ssh *remote* port forwarding?

I need to limit which ports can be remotely 'ssh -R' forwarded by an user. I know about permitopen option on authorized_keys, but as it says on man page it only limits local 'ssh -L' port forwarding ...
1
vote
1answer
77 views

keeping keys on an auxiliary removable drive

It seems that servers are only as secure as the machine that holds the keys and that in turn means the desktop/screensaver password is the line of defence for not only the desktop itself but any ...
14
votes
4answers
13k 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 ...)
0
votes
4answers
331 views

securing SSH and disabling direct root

In these instructions below what appears on my terminal is different so not sure what I should change. After port 22 mine says #AddressFamily any and further down for protocol it has longer line ...
2
votes
1answer
131 views

is it secure /not dangerous to ssh with keys through public transparent proxy?

I use pub key for ssh. Is it normal practice to connect to own server through public proxy? I think with plain pass it is surely dangerous but how about RSA keys?
2
votes
3answers
529 views

rsync server/daemon security

I have a NAS (Netgear Readynas NV+) at home and a linux (Arch) box at work that is always on. The linux box is already running an ssh server/daemon and the NAS is already running an rsync ...
5
votes
2answers
372 views

How to disable login for an user?

My Linux has many not-human users like cron, ntp, daemon, http, etc. I want to disable anybody to login as any of this users. Real people on my machine are root and me, so only root and me should be ...
1
vote
1answer
658 views

Safety of SMB versus SFTP

I have a server with OpenSSH enabled. I use it to make distant backups. I mainly use rsync over SSH and SFTP. I understood that these protocols are quite safe. I am interested in enabling Samba share ...
2
votes
1answer
461 views

Is it *really* possible to directly steal a private key if it uses no passphrase?

I've read in various places, such as in this question that using an ssh key pair without a passphrase allows attackers to steal your private key if they gain access to your account. I assumed that by ...
2
votes
2answers
134 views

SSH encryption security

If I log in to my server through ssh and copy files to my local computer can I be eavesdropped? How do I make sure nobody can intercept the data or even know what I am copying? Are there levels of ...
5
votes
1answer
248 views

Automated ssh login with passphrase?

Logging onto a machine over ssh typically requires a password to be entered before access is granted. Alternatively, a key/certificate (without a passphrase) can be installed onto the remote machine ...
5
votes
2answers
7k 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
545 views

Is encrypting your web browsing via SSH to localhost useful?

For example, if I did an ssh -X to localhost and invoked Firefox, would that be enough to be considered safe browsing, like if done on some public wifi?
0
votes
1answer
731 views

What is the default encryption type of the ssh-keygen?

When generating private/public keys with ssh-keygen what types of keys will it generate if I wont pass -t option followed with the encryption type like rsa?
5
votes
4answers
19k views

SSH login with clear text password as a parameter?

I need to login to a user that I've created on a remote host running Ubuntu. I can't use an ssh key because the ssh login will happen from a bash script ran within a server that I wont have access to ...
3
votes
1answer
176 views

How are loaded SSH keys referenced by name?

I'm using chef's knife ec2 tool which requires the name of a loaded SSH key (that was created in the Amazon EC2 control panel) It seems strange to me that it uses a name to reference the keypair - ...
3
votes
1answer
205 views

SSH Bash Jail Session

I've seen some game tunneling service providers that jails the customer's account to a Information screen upon login and any input is ignored. Ctrl+C closes the SSH session, and disconnecting. This ...