I am running a fresh installation of RHEL 6 box and it shipped with Openssh 5.3.But, /etc/ssh/moduli file doesn't exist even in this new installation and the SSH log warns as below:PHP Code:WARNING: /etc/ssh/moduli does not exist, using fixed modulusDoes this imply that it is using the same random number for key exchange purpose ? Also, does it impose any security risks
View 2 RepliesI want to enable sshd from Internet, but I want to secure it as much as possible.Therefore, despite the fact that the service will run on a tcp port above 2000 to prevent most scans, I would like to :- First, force the use of a client certificate, to avoid brute force attack on my users/passwords- second force the use of a username/password to avoid someone having access to my system just by stealing my key..When I look at the configuration, it's possible to enable both, but one of them is sufficient to login, but I can't find how to make them both mandatory...
View 2 Replies View RelatedI have a RHEL server with users logging in via ssh. I want to start using public keys instead of passwords with ssh. But public key is as good as a rotten tomato if it is unpassphrased and I cannot guarantee that all users will use passphrases. Therefore I will generate both private and public key on the server and will distribute the private key to the user via user-friendly web interface and thats where I will force them to use passphrase. I know they can change later the passphrase or remove it totally but my users are not so advanced.
So now I am trying to setup a centralized authorized_keys file with to be able to make them only root writable so they cannot put their own public keys on the server , it will be handled by scripts. Now the actual problem. I created /etc/ssh/keys directory instead of ~/.ssh and changed AuthorizedKeysFile to /etc/ssh/keys/%u in sshd_config But when I try to connect with the key I get the following error in the logs (after enabling DEBUG3 in sshd_config)
<CUT>
Mar 8 15:22:28 stagesmpp sshd[12248]: debug3: mm_request_receive entering
Mar 8 15:22:29 stagesmpp sshd[22358]: debug2: channel 0: rcvd adjust 33544
Mar 8 15:22:30 stagesmpp sshd[12248]: debug3: monitor_read: checking request 20
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Quick explanation about what this thread is: by way of an article featured on linuxtoday, I learned about what appears to be an actively managed IP blacklist: [URL]
# This is a compiled list of dirty hosts associated with
# bruteforcing attempts, spam, botnets, RBN and the list
# continues to grow. The data is comprised of information
# compiled from Arbor Networks, Project Honeypot, FIRE
# (maliciousnetwork.org), Host Exploit, Shadowserver and
# a variety of other similarly based sites.
Quick explanation about what this thread is not: this is not intended to be a discussion about default deny vs. default allow (i.e. whitelists vs. blacklists), nor is this a call for enumerations of your own sshd hardening strategy. Please try to keep on point. That said, can anyone speak to the quality of the blacklist information noted above? And/or are there any suggestions for a readily available blacklist of "known better" quality? I plan to try including an actively maintained blacklist like this into a multi-layered approach for hardening an sshd bastion host.
What's with todays updates? Webkit librarys and Firefox updates. Was there a security issue that's just recently been fixed? Just wondering, I'm obviously going to install them.
View 1 Replies View RelatedI have an sshd server up and running (F13 64bit) I'd like to connect to a pc that's behind a firewall using ssh tunnelling, so I have something like
ssh -R 1234:127.0.0.1:22 myuser@mypc
then from mypc I can succesfully login to the remote pc. I have just une question. How can I list the ssh active connections and the forwarded ports ?
I've only got to
netstat -tunva
but this returns only (filtered)
tcp 0 0 127.0.0.1:1234 0.0.0.0:* LISTEN
tcp 0 0 ::ffff:172.16.0.XXX:22 ::ffff:172.16.1.XXX:60744 ESTABLISHED
Now I know that the first is the tunnel end but how can I connect the two lines if I don't know the port number (ie: someone else estabilieshes another tunnel)
I'm having troubles trying to understand this problem:my homeserver until yesterday had a public IP, staying on network, with sshd running and all was fine;this evening I changed the IP, giving it a local lan address, and what happened if I tried to connect to it by ssh?I got an error about "Connection closed by remote host". Google helped me finding that was regarded to hosts.deny file, that was actually containing a lineALL:ALLthat I commented, and all was fine.My question is: why the hosts.deny (that has never changed) was observed only with the local IP?I tried to switch back to the public IP and leaving ALL:ALL, and it did connect without any problem
View 1 Replies View RelatedWhat is happening when I log in to my Ubuntu server machine via ssh and putty. trying to understand everything, primarily securing my server.
I have specified the ssh server to listen on port 5525, and can login without a problem.
When I look at the logs though it says I connected from xxx.xx.xx.xx on port 53602.
What is happening here and why is the logged connection a different port to the one specified in the config file?
I've been using ssh for a LONG time to connect my laptop to my desktop with no problems. I use a non-standard port (nnnnn) and keys. After a power outage that caused a shutdown and reboot, I can no longer ssh into the desktop. The only changes I've made are updates (laptop and desktop both running ubuntu 10.04).
$ ssh -p nnnnn Desktop
ssh: connect to host Desktop port nnnnn: Connection refused
No messages are generated in any of the logs on Desktop!
$ /usr/sbin/sshd -T
port nnnnn
protocol 2
addressfamily any
listenaddress 0.0.0.0:12023
listenaddress [::]:12023 .....
I'm trying to setup ssh access on my Fedora 12 laptop. I get the following error message in /var/log/secure when I try to login from another machine using ssh and the login is denied:
Code:
sshd[3025]: error: Could not get shadow information for <user>
sshd[3025]: Failed password for <user> from <ip> port <port> ssh2
If I do a 'setenforce 0' I can login and no error is logged.
When a user that has rsa public key set in ~/.ssh/authorized_keys file logs in via ssh an sshd process is started to handle the ssh session.Periodically we audit the authorized keys and remove them from the system and authorized_keys file. This means the next log in attempt will fail, which is fine.However we need to terminate current ssh sessions in progress that use the rsa key.I have not been able to determine a way to map sshd processes with authorized_keys entries.
View 11 Replies View RelatedQuote:
Code:
I've used these commands to generate my new keys and immediately got my sshd server running.
However, I now have the problem where the password is not being recognized and is repeatedly asked for.
Tried google and searching this forum to no avail. Under Fedora 14, there is an selinux policy which blocks sshd from making outbound connections on port 80 or 443. This can occur when a client box tries to tunnel through the ssh connection for encrypted access to the web.
While I did manage to allow this happen by creating a permissive domain for sshd with this command:
Code:
The preferred way would be to allow sshd to make connection on other ports with a similar command that does not seem to work:
Code:
Is this the correct way of allowing an outbound port connection for the sshd daemon?
Is there an ssh or sshd parameter that can be set to block out a user after a set number of attempts tp login ?
View 1 Replies View RelatedI have a problem with sshd daemon on a target linux system:The system has only one user (root) without password.The sshd_config looks like:
Code:
Port 22
Protocol 2
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Using slackware 12.2, xfce, Firefox 3.0.16 and for the past few days i have been getting Persistent System Security Window that looks like MS Firewall and you can't click on the X or Cancel because then it activates a so called security analysis with green progress bar. I open a terminal real quick and issue pkill firefox command.I have been trying to get to the basicconfig site to follow tutorial on firefox security update but that window keeps comming back.I emptied out my /tmp files but i am still having same problem and don't know what to do
View 4 Replies View RelatedI have an Asus 900 laptop that I put Ubuntu 9.10 on.I know it was made by the Chinese, but why are they trying to hack my pc?I currently put FIRESTARTER a linux firewall on board you can go here to get itNow I can see everyone's IP address and find out where they are and who they are!!
View 9 Replies View RelatedJust I install the rkhunter tool via apt-get install rkhunter. When I had run the rkhunter check, rkhunter comes with a warning about "GasKit Rootkit", i dont understand what it is
This server is install new last and maby 1 week old, so i don't understand why this happends.
i get this warning from selinux :
"SELinux is preventing /bin/mailx from append access on the file /var/lib/rkhunter/rkhcronlog.OmRFCZOynG."
I tried to fix it by "# /sbin/restorecon -v /var/lib/rkhunter/rkhcronlog.OmRFCZOynG" as suggested by SELinux but it comes back with another warning, but with a different /rkhcronlog.xxxxxxxxx...
i think its just a way of rkhunter logging issue -. attached here is the actual error message by selinux.
When I scanned my Ubuntu 10.04 with rkhunter a root kit hunter toolkit, it gave following warning:
Is there something that I have to worry about.
Code:
I had a serious breach of the cellular segment of my communications network this week. All I can say is nobody got hurt. The attackers also knew where to find me via email. I'm concerned that perhaps they've penetrated this aspect of my system as well, although they seemed pretty specifically focused on the phone. There have been no changes on anything on my computer, and of course, I went ahead and changed all the passwords. How can I verify or at least look into the possibility of having been hacked as well.
View 8 Replies View RelatedSometimes when I try to open some chat application i get a strange warning message asking for password. The message is that /usr/libexec/mission-control is trying to gain access of the system, please provide the password. On top of the message box it shows "Unlock Keyring".
This very weird, as I am also unable to do a print-screen when this message box is up.
what this message is all about and what does the executable /usr/libexec/mission-control do?
I am using Empathy as my chat application
I had been receiving a rkhunter warning on my Fedora 14 server for quite some time now. Attempts to fix the error via information from Google searches have failed. I decided to have a look at bugzilla and what do you know, a fix. The warning:
Quote:
[03:29:08] Warning: The SSH and rkhunter configuration options should be the same:
Warning: The SSH and rkhunter configuration options should be the same:
The fix, according to https://bugzilla.redhat.com/show_bug.cgi?id=596775 is to change
PHP Code:
ALLOW_SSH_PROT_V1=2
to
PHP Code:
ALLOW_SSH_PROT_V1=0
I made the change and ran rkhunter again. No more error. I know everyone was wondering about this.
I was updating the files I have from packman on my test box and got security warning on mplayer and gixine. I switched mirrors and got the same checksum errors on a totally different mirror except I was not re-offered mplayer once I refused it the first time.
View 9 Replies View RelatedI've scanned my computer (I'm using Ubuntu 8.04 Hardy Heron) and ClamAV has issued it has found a virus called Exploit.PDF-9669. What seems strange to me is that such a warning always happens (or, at least, in the most cases) in the same folder tree "sys" and ClamAV issues the very same virus/malware warning (Exploit.PDF-9669).
An example:
sys/devices/virtual/vtconsole/vtcon0/uevent: Exploit.PDF-9669 FOUND
sys/devices/virtual/net/ppp0/address: Exploit.PDF-9669 FOUND
sys/devices/virtual/net/ppp0/broadcast: Exploit.PDF-9669 FOUND
sys/devices/LNXSYSTM:00/device:00/uevent: Exploit.PDF-9669 FOUND
My ClamAV version is 0.94.2/10275/Fri Jan 8 22:06:46 2010. It has been not updated since I installed Hardy in my computer last year. Is my computer in danger?
I'm relatively new to Ubuntu and these forums. I ran rkhunter, and saw this warning in the check for backdoor ports: [14:45:09] Warning: Network TCP port 32982 is being used by /usr/bin/python2.6. Possible rootkit: Solaris Wanuk Use the 'lsof -i' or 'netstat -an' command to check this. I also saw these warnings toward the bottom:
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I was wondering first of all about the first warning, the port. I have a feeling that the second set of warnings are false positives, but I would be open to thoughts on that as well.
I'm not concerned about this since this traffic is generated from the loopback address, but would like to find out what it is.
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Trying to install the Suhosin module with the php 5.2.9 c5-testing repo...it won't run with the php 5.2.9 testing build (there isn't an updated suhosin package against the 5.2.9 build)
PHP Warning: PHP Startup: suhosin: Unable to initialize module
Module compiled with module API=20050922, debug=0, thread-safety=0
PHP compiled with module API=20060613, debug=0, thread-safety=0
What's the best way to handle this from an admin best practices standpoint? I want to do everything possible to keep the suhosin module tracked by yum for future updating etc. Is it best to try to find a suhosin rpm that is built for 5.2.9 and install it with yum localinstall? If not, if I build the module myself, what's the best path to keeping yum/rpm in the loop on this install for future updating via yum?
I am still probably of the windows mindset when it comes to security. I ran rootkit this morning and received the following error messages;
[09:43:49] /usr/sbin/unhide [ Warning ]
[09:43:49] Warning: The file '/usr/sbin/unhide' exists on the system, but it is not present in the rkhunter.dat file.
09:43:49] /usr/sbin/unhide-linux26 [ Warning ]
[code]....
Like Jackp27, I am reacting to a transient warning from rkhunter, indicating a possible LKM trojan, which may or may not be a false positive. Running chkrootkit and rkhunter repeatedly, including older versions running under live CDs like INSERT, indicated nothing wrong, but two runs of rkhunter running under the possibly compromised system itself did seem to suggest rkhunter thought it might have found elements of trojan code in RAM.
Like Jackp27, I can't give details right now because I do not currently have access to my logs, but I did find one webpage (can't give link because I do not currently have access to my detailed notes) suggesting that rkhunter may have thought it found a signature of the adore trojan in RAM by looking at /proc/kallsymms which is not a file I ordinary look at. I did look at it very closely yesterday, repeatedly, and it seems to be mostly empty, but occasionaly seems to contain what might be a sequence of calls to various kernel modules--- right now I only recall that some had the form ??_guest_? and that x_tables might be involved.
Can anyone give me a rough indication of what /proc/kallsymms is supposed to do, whether it should normally be empty, and when it is not, what kind of lines are supposed to show up in that "file" when I cat it? I also saw something about ?_logdrop? which may have had something to do with with rotating logs (I rebooted several times) rather than a trojan keylogger. But maybe some trojans rotate logs to try to hide their presence?
I know I am not giving enough information--- I hope to come back later with more details after I have managed to access my logs and notes, so feel free to say what kind of details would be most helpful in helping me decide whether or not this was a false positive.