Ubuntu Security :: Firewall Showing SSH Attempts Quite Often
Sep 30, 2010
I'm running the firestarter firewall and its been showing the odd ssh attempt quite often. e.g. I've had 4 attempts today, 3 in the last 40mins. I realize that this may be nothing to serious but it's got me curious, aside from having a secure password (which I have) is there anything that else that I can do to ensure that my system is as secure as possible from ssh? I do use ssh within my home network so I don't want to disable it completely.
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Jun 29, 2010
How can I set up snort to only log and detect/capture logins using root or any of the "homeusers" login accounts or names?
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Oct 23, 2010
I have an SSH server on my laptop, and I'm using the default configuration file, but I added "AllowUsers <myUserName>". I get lots of login attempts like the ones below in my /var/log/auth.log.From Google, I find that pam_winbind allows some kind of Windows authentication. This leaves me with 2 questions. What does winbind do when I have not configured any Windows/Samba accounts? How can I turn it off?
Code:
Oct 23 20:01:49 muon sshd[24329]: User root from 201.116.17.163 not allowed because not listed in AllowUsers
[code]...
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May 9, 2011
Can we use iptables as firewall instead of Juniper firewall
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Mar 22, 2011
I am running a ubuntu server 10.10 with SSH, and OpenVPN. I use it mainly for the VPN, but I have seen log in attempts such as:
Mar 22 14:52:53 UbuntuSvr sshd[2397]: Invalid user support from 85.217.190.69
Mar 22 14:52:55 UbuntuSvr sshd[2399]: Invalid user student from 85.217.190.69
Mar 22 14:52:57 UbuntuSvr sshd[2401]: Invalid user transfer from 85.217.190.69
Mar 22 14:52:59 UbuntuSvr sshd[2403]: Invalid user user from 85.217.190.69
[Code]...
Is it possible to make it so when some one has tried logging in 5 times with an invalid user/pass that the ip is banned for 10 minutes? I have password auth set to no and am using keys.
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Apr 28, 2009
I know this is probably easy and if I only took a while to figure it out maybe I could but I have some stuff that needs to happen soon and I can't figure this out. I was wondering how I could have a log monitor that would email me whenever someone tries to login over ssh to my system. I'm open to everything daemons/scripts or cron itl works as I am not running a production server (but I might be starting that soon). Oh and just a side how do I get sent an email when I get port scanned
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Nov 15, 2009
I have a server box behind my ISP router at home, and I need to allow ssh access to my server. My ISP router doesn't let me allow selectively ssh from some IP. It allows ssh to everyone.
I have fedora10 and openssh-server-5.1p1-3. How can I configure openssh to allow just from 1 IP?
Does it use xinetd at all and the hosts.allow and .deny mechanism?
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Nov 18, 2010
I run SSH on a publicly open server and see following attempts in /var/log/auth.log which I was told by some one could be port scanning attempts.(Not sure though)
Code:
Nov 18 23:50:19 server sshd[21716]: Did not receive identification string from 186.0.80.197
Nov 19 00:05:57 server sshd[24056]: Did not receive identification string from 85.108.110.66
How can I block above such attempts?
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May 20, 2010
How does one unlock an account when it is locked by too many failed attempts for login?
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Jan 15, 2011
I'd like to limit login attempts for specific user. I've found information in manpages: [URL]but I'm not sure if this '@' is purposly there, so would be that correct?
Code:
aparaho - maxlogins 4
or
Code:
@aparaho - maxlogins 4
Maybe '@' is a group syntax? I'm confused.
What happens after 4 failed loggins? Is it enough to restart system to get another login attempts?
Are there any other values that it is reasonable to limit for safety reasons?
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May 25, 2010
I'm trying to lock an account after a number of failed login attempts in a RHEL5.
This is the relevant configuration in /etc/pam.d/system-auth
In the logs I can see how the count of failed logins increase and exceeds my deny option but the account isn't locked
Do I need any other option in the PAM file? Is there any other way to lock an account?
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Aug 9, 2010
My server (CentOS 5.4) is being bombarded 24x7 with IP addresses from China trying to exploit phpMyAdmin. For every one I block on the firewall, half a dozen come to the funeral! It's a pity these morons don't have something better to occupy their time. I'm getting page after page of this (see below) every day and it's been going on for weeks. I don't even have phpMyAdmin on the server. I don't use it and I deleted it.
I've read that you can use .htaccess and / or mod_rewrite to redirect / block them based on any query for phpMyAdmin (they try all letters in upper and lower case, leading to page after page). Unfortunately, I have no idea of how to do this. I already have an .htaccess file. Maybe someone can suggest what to add to stop these pests from wasting my bandwidth and suggest somewhere I could redirect them to to cause them maximum problems. I don't want to block the entire country, seems a bit like overkill, not all Chinese are morons. we aren't even in the USA, so why they are doing this is beyond me.
A TINY sample!
[Sun Aug 08 13:29:08 2010] [error] [client 61.191.41.53] File does not exist: /var/www/corp/phpMyAdmin-2.7.2
[code]...
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Apr 1, 2011
I want to count the failure root login attempts so that do an action when the user faild to login as root for three consecutive times (like log a line in syslog).
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Feb 16, 2011
I am trying to get OpenLDAP to authenticate user logins, but running around in circles. Are there any logs produced by either client and/or server that would indicate possible reasons why it was unable to login as a user?Below is an explanation, any ideas would be appreciated, as I think everything is setup as per the various articles on using LDAP.
I have a CentOS 5.5 OpenLDAP server, and several others, some host services, some are file shares (samba).So far I have been able to successfully configure OpenLDAP to carry out all the ldap* commands from both the local server and from any of the remote servers, either via non-ssl or ssl connections. However, as soon as I try connecting any services up to it, it doesn't play ball.Back to basics, having cleared off all previous attempts at this from all machines, I have gone through the following:
Installed OpenLDAP server/client on host (plus nss_ldap).
Configured /etc/openldap/slapd.conf (see below)
Configured /etc/openldap/ldap.conf (see below)
[code]...
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Jul 22, 2010
currently I'm fiddling around with mod_security for apache2 configurations on CentOS boxes, right now in a test environment first (i.e. separate non production box).CentOS includes the mod_security "Core Rule Set" by Breach Security Inc, the devs behind that module.So far all's running mostly, logs/auditlogs etc.For simple testing, I made a small php form as following:
Code:
<?php
$link = mysql_connect("localhost",$user,$pass); //un/pw obfuscated for forum post
[code]...
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Oct 22, 2010
On my server I some times login from my home where I have an internet connection which does not have a static IP each time I switch on my modem a dynamic IP isgenerated.I see in auth.log logs of following lines Quote:reverse mapping checking getaddrinfo forkkts-kk-dynamic-01.1.168.192.some_broadband.in [192.168.1.2] failed - POSSIBLE BREAK-IN ATTEMPT Accepted publickey for root from 192.168.1.2 port 22852 ssh2when ever I login to my server from home.In this case I do know that it was me who logged in but still why do I see such a log.What is this complaining about?
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Apr 28, 2011
Is there an ssh or sshd parameter that can be set to block out a user after a set number of attempts tp login ?
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Oct 28, 2010
I am using denyhosts on a server so in a config file/etc/denyhosts.confthe following value is setQuote:DENY_THRESHOLD_INVALID = 3which as per their configuration file saysQuote:
DENY_THRESHOLD_INVALID: block each host after the number of failed login
# attempts has exceeded this value. This value applies to invalid
# user login attempts (eg. non-existent user accounts)
[code]...
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Sep 23, 2010
I have a Suse11 box with 2 network cards:
I have squid as a proxy on the Suse box, and with the default firewall I have to enable masquerading to allow clients on the eth3:1-3 to send and receive mail through the Suse box. I found the Suse firewall completely inadequate (all P2P software/connections are allowed once you enable masquerading) and had to install ConfigServer Security & Firewall. In die configuration of csf I could get my way around getting smtp to work for the eth3:1-3 clients, but pop3 connections does not go through the box. I know I need to allow port 110 and 995 to masquerade of NAT (or something) and then the same for port 22
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Feb 23, 2011
I tried installing F-prot's linux scanner but it doesn't seem to want to install and I am tired of messing with it.
So I am wondering if I even need it or if there is something else.
I am behind a firewall already with my router if that helps any.
I guess I am having trouble understanding why virus protection is less necessary.
Do people not write viruses for linux systems?
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Jul 20, 2010
I have Ubuntu running on an old PE server. It is running Virtualbox with an instance of Ubuntu inside. The instance is there to run my honeypot.
The server box IP is192.168.1.10. The Virtualbox is bridged with it's own IP of 192.168.1.200. The honeypot daemon is listening to 192.168.1.201 with arpd.
I set up the UFW with DENY. And then enabled only the ports leading to the honeypot scripts which are abound to IP .201. I then forwarded the ports necessary to run VNC to .200.
Here is the UFW status:
buntu@ubuntu-desktop:/var/lib$ sudo ufw status
Status: active
To Action From
-- ------ ----
192.168.1.201 21/tcp ALLOW 21/tcp
192.168.1.201 4444/tcp ALLOW 4444/tcp
192.168.1.201 5544/tcp ALLOW 5544/tcp
[Code].....
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May 23, 2010
Will I need to actiavte the firewall that comes with Ubuntu since I'm using Transmission?
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Aug 13, 2010
I am new to the Ubuntu/Linix world (less than a week).
I have tried the search, but have had difficulty finding threads on this.
Can someone recommend an excellent firewall to use with Ubuntu?
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Aug 14, 2010
I have a VPS (Ubuntu 8.04 server eition) and as such am stuck with using a software firewall.
i currently have UFW installed.
I would ideally like to have my firewall be a little rude, or rather just not polite. I know what i am asking will break the RFC, but i consider this ok due to the security benefits.
I would like to have my firewall
1) ignore (eg drop without responding)all packets that dont start with a syn flag
2)for all other traffic that is currently blocked, have it dropped (again drop it without responding)
If there are any other rules you can think of i would like to know them. I already have only the services i want open and the rest blocked.
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Nov 4, 2010
I've been using Windows for quite a few years now. I loved the way how I used to set incoming/outgoing rules for my applications. But I'm having hard time doing that in Ubuntu. I tried searching for a good GUI for iptables but I need your help selecting the best. I might learn iptables someday but for the time being I will be using a nice GUI. I'm currently using GUFW, I've tried Firestarter. All I need is a firewall that would allow me to configure rules for my applications.
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Jun 15, 2011
I have set up a Ubuntu 10.10 server. I have been using ssh tunnels to encrypt my web traffic at public wifi. I am trying to make this server as secure as posible so I enabled ufw. I allowed SSH and HTTP traffic in and denied everything else. But when I do that I can not use SSH -D because when I try to visit a webpage it does not load and I get the following.
Code:
uname@mybox:~$ channel 3: open failed: connect failed: Connection timed out
^C
uname@mybox:~$ fclchannel 4: open failed: connect failed: Connection timed out
^C
uname@mybox:~$ exit
logout
What do I have to do to allow ufw to allow ssh tunnels through?
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Jun 21, 2011
I am a Linux newbie so please bear with me if I sound stupid. I was checking out how to set up a firewall for my system and landed on this webpage: [URL]. But I am so confused with how this ufw application works. What I understand is that once I set it to "default deny" it prevents unauthorized incoming connection but what does it mean when the author says to add exceptions for services I need? When do I need to do that? Also what's an SSH server?
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Feb 13, 2010
i want set up IDS(Intrusion detection system) and Firewall in my home just for learning.. The Goal is learn IDS log and Firewall log..
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Apr 14, 2010
I'm involved in a project to students set up a network security training lab using vmware. I want to simulate (in a very rough way) scanning through a poorly configured router or firewall. The easiest way I can think of to simulate this is to use a linux vmware image with two virtual nic cards to act as a firewall with the attacker on the outside network and a domain controller, web server, and database server on the inside network.
I would like to start students off with a firewall script that exposes everything on their internal network to the attacker. Is there an easy way to (mis)configure iptables to do this?. The model I'm trying to replicate is something like this. Attackers were on a 10.10.x.x network, defenders were on a 192.168.x.x network. As an attacker I could nmap 192.168.x.x and see every machine and every service on the defenders side even if they moved a service to an unexpected location. how I can implement a similar configuration using a linux image as firewalls/routers in vmware?
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May 9, 2010
I have a set of iptables rules generated by Firestarter, and i'm in the process of trying to familiarise myself with iptables itself, but there's one particular rule which is confusing me, perhaps somebody could explain it to me
My INPUT chain reads as follows:
Code:
Chain INPUT (policy DROP)
target prot opt source destination
ACCEPT tcp -- cdns01.plus.net anywhere tcp flags:!FIN,SYN,RST,ACK/SYN
ACCEPT udp -- cdns01.plus.net anywhere
ACCEPT tcp -- cdns02.plus.net anywhere tcp flags:!FIN,SYN,RST,ACK/SYN
[Code]...
Given that the firewall is actually blocking packets, it can't be this simple, so what am I missing?
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