Where I work we have a lan, it is almost 100% windows machines except for 2 CentOS machines in which some clients connect to, via VPN. (very small network, <50 ip's used)
I would like to know if there is a way to block access from that machines to others in the network. I'm already logging traffic (with IPTraff) to see if they're accessing other machines in the network others than the ones they should connect.
I set up iptables but it is blocking my SSH set up. I did allow it by opening port 22 but it did not work. Here is my config:
Code:
iptables -F
iptables -P OUTPUT ACCEPT
iptables -P INPUT DROP
iptables -P FORWARD DROP
### this should allow SSH traffic
iptables -A INPUT -p tcp --dport 22 -j ACCEPT
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
How do you allow SSH through the iptables firewall?
i used the angry ip scan software and found alot of the public ip addresses on our network are accessable from outside when they are not suppose to, For eg printers/ pcs etc. to make a start on locking down the network i was wondering if anybody knew th iptables command to add a rule which blocked all incoming traffic to specific ip adresses on the network and to a range of ip addresses.
View 7 Replies View RelatedIs there a way to configure my interface to promisc mode and also make it not capture the "transmitted" packets. ?I mean, i want the interface in Promisc mode but only for inbound traffic.If there isnt any using ifconfig, can it be by configuring eth0 to promisc using ifconfig , and filtering outbound traffic from being captured using sockets or something ?
View 4 Replies View RelatedI have a remote network that I manage consisting of a DLink DFL-210 firewall/router, and behind that a Dell server running openSUSE 11.2 and a collection of Windows XP/Vista/7 computers.
The Linux box is running OpenVPN as a server (that is how I connect to this network) and a client (it connects to a second server - running XP - at a different location).
The DLink router is the DHCP server and provides addresses on the 192.168.51.0/24 network. The OpenVPN server provides the 10.8.51.0/24 address range.
The remote network that the Linux box connects to is 192.168.54.0/24 via the OpenVPN network 10.8.54.0/24.
I have added routes to the DLink router to route all traffic to the 10.8.51.0/24 and 192.168.54.0/24 networks to the Linux box.
With SUSEFirewall turned off, after I have connected via OpenVPN from my remote computer I can ping all active 192.168.51.0/24 addresses. Other computers on the 192.168.51.0/24 network can ping computers on the 192.168.54.0/24 network. But if I turn on SUSEFirewall, neither of these work. However, I can ping 10.8.54.1 from any computer on the 192.168.51.0/24 network.
How can I set up SUSEFirewall to allow these networks to communicate with eachother?
I need to log outbound (server -> remote) ssh traffic, but am unsure of the best way to do this.
I added this to iptables, but nothing is being written to the logs when I ssh from the server to another system.
iptables -A OUTPUT -m state --state NEW -j LOG --log-uid iptables-save
Summary: Several school networks in need of a fairly low-level way to log network use, especially Internet. Raw packet captures are too low (and big). Turnkey solutions we've looked at (Untangle) aren't really a good fit. This seems like a common issue. Detail: For legal reasons, we have to be able to roll back time every so often (ie. when death-threats are made on some web-forum). Currently, our traffic logs on Internet traffic are pretty high-level and aren't really useful to point a finger at the guilty or away from the innocent. We also like to keep our users honest by providing them with data about their own computer use (ie. what are the top 10 websites they hit).
I've been building up rules with iptables and ulogd to log the creation of new connections and save it to a PCAP formatted file for consumption by some very simple analysis scripts, or examination with Wireshark if required. Just logging new connections prevents the logging data from getting large in a hurry, but also doesn't give us a lot of information we would like (ie. the amount of data transferred). We've been examining products that offer fairly full-featured analysis, notably Untangle, but we do a lot of weird stuff (VOIP, VC, VPNs) with traffic flowing through very minimal hardware (PC Engines) running Linux. This is very inexpensive and very flexible, and we like it that way.
As too my question, at this time I dont control the router/firewall an I would like to block a port thats used for guild wars on my workstation for a while. The reason for blocking is children have abused it an lost it.In this case I am trying to block outgoing traffic on port 6112. I have tried setting up a proxy server on the workstation, but the game seems to ignore it an jump on. Due to the environment, I enabled the workstation SuSEFirewall2 firewall an tried setting up "lo" as a internal an configure the firewall as a router, then disable 0/0 an configured for 0/0,tcp,443 an re route port 80 traffic to proxy.
When I had my own internet, I had a transparent proxy enforcing rules for access times. So setting up a proxy on each machine would not be a bad thing, even if it took some creative thinking. I am trying, but seem to be missing something.Ideally, I would like to setup a transparent proxy, as my kids have learned alot about system administration an know to check the proxy module. If all they have to do is un check "Use Proxy" an by pass a local proxy server, then I am kinda defeated. An applications such as firefox have a proxy setting they could set to none instead of system
Recently I notice that when I'm connected to an vpn server (pptpd) and I'm using it as a default gateway my download and upload speed decreases almost to the half of the usual speed. I made a test using iptables in order to count how much GRE packets are generated (except the real traffic itself) in that way:
Code:
iptables -I INPUT -p gre -j ACCEPT
iptables -I OUTPUT -p gre -j ACCEPT
iptables -I FORWARD -s 172.16.10.101 -j ACCEPT
iptables -I FORWARD -d 172.16.10.101 -j ACCEPT
The first 2 rules match all GRE packets between the pptpd server and client, and the next rules - the traffic between the server and the client.
When I turn the counters to zero and begin to generate traffic (to browse, to download etc.) I see that the GRE packets are even more than these in the FORWARD chain.
So, my question is first of all is my test correct and is it true that so much gre traffic is being generated during the browsing (it becames clear that the traffic is double than if the pptpd wasn't used as a gateway) and if yes - can that traffic be reduced?
I can see what Firestarter is blocking in the Firestarter/Events tab, but after reading all the man pages of UFW, I still don't know how to check what the UFW is blocking.
View 9 Replies View RelatedAfter reading a lot about networking and security I decided to check the security of my own ubuntu box. So I went installing Nmap and discovered that port 139 was "open". Since I 'd read how to use ufw I created a deny rule for port 139. After a second scan with Nmap it still said that port 139 was open as shown below.
[Code]...
im having a bit of a problem with Firestarter, i have Transmission opened and i am downloading a movie but when i check Firestarter i see hundreds and hundreds of Ip's that are blocked, and like 10ip's every second that get blocked.
[Code].....
I have the default to deny all. The only rule I have in there is:
Code:
To Action From
-- ------ ----
[code]....
I might be misunderstanding the log but it looks like UFW is blocking connections. I want to allow all incoming and outgoing. I guess what I'm saying is that the servers on my computer will open ports but all other ports should respond with closed just like a default Ubuntu install. Trying to use UFW to monitor connections without really doing any firewalling.
Code:
Aug 1 07:14:07 universal-mechanism kernel: [311111.963762] [UFW BLOCK] IN=eth0 OUT= MAC=00:1f:c6:8a:e9:66:00:01:5c:32:f4:c1:08:00 SRC=72.21.203.146 DST=174.44.178.56 LEN=40 TOS=0x00 PREC=0x00 TTL=233 ID=51984 DF PROTO=TCP SPT=80 DPT=54466 WINDOW=8201 RES=0x00 RST URGP=0
Is possible blocking web with content for adults with iptables?
View 3 Replies View RelatedWhen I turn on my SeLinux to enforcing mode on my Red Hat system ssh stops working and my http server stops responding.
I went into the SeLinux GUI and enabled things in there but still it wont work.
Any thoughts on what to check?
permissive mode and disabled they work
I read several articles that say it should not be affect by SeLinux and the setting look correct but the only thing I do is turn on SeLinux and ssh /httpd stop working
ps -eZ | grep sshd
system_u:system_r:unconfined_t:SystemLow-SystemHigh 432 ? 00:00:00 sshd
system_u:system_r:unconfined_t:SystemLow-SystemHigh 2426 ? 00:00:00 sshd
[root@goxsa1340 ~]# ps -eZ | grep httpd
user_u:system_r:httpd_t 3044 ? 00:00:00 httpd
[Code].....
I am running Fedora 11 and every time i plug in my iPod it tells me... SELinux is preventing mkdir (podsleuth_t) "read" security_t ... I have no idea on how to create a policy module to allow access.
View 2 Replies View RelatedIn fedora 12 how can i configure the system such that a particular user can browse only selected web sites.
View 9 Replies View RelatedI want to ask about securing the FTP connection... I have one server that Installed with Redhat Linux Fedora 6.
And now, i want to securing the FTP access, so only the selected IP will be allowed to connect. Do anyone know how to do this?
Another thing is, my server using Webmin 1.3 to manage the server and there not installed / not configured yet with Frox FTP, ProFTPD Server, WU-FTP Server... even there is such thing in my Webmin...
Can i make use one of the three FTP i mention above, and if yes, will it be affecting the current FTP access?
I'm assuming that the following should block the complete 178.123.xxx.xxx address range.
Code:
iptables -I INPUT -s 178.123.0.0/24 -j DROP
Then I believe that I need to save this change.
Code:
service iptables save
iptables: Saving firewall rules to /etc/sysconfig/iptables:[ OK ]
However, I'm not so sure that it is actually working based on the fact that there continues to be access to my wiki from that address range. The following is after I made the firewall change.
Quote:
178.123.177.61 - - [31/Dec/2010:04:24:40 -0500] "GET /mywiki/Opera%20Web%20Browser?action=edit&editor=text HTTP/1.1" 200 6346 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)"
code....
Let me state that I'm new at this iptables thing. I did some reading and decided that I need to make the above change to the firewall but it doesn't seem to make a difference.
since I upgraded to F15 I noticed that "su -l" is very slow, it takes about 20sec before it gives the prompt. I traced it down to a problem with "xauth" as su asks for the authorization for the display running "xauth nlist :0" which times out with an error. Actually, the command "xauth nlist :0" by itself gives:
xauth: timeout in locking authority file /home/user/.kde/tmp-host.domain/xauth-200-_0
If I put SELinux in permissive mode both command work without problem so I suppose SEL is the problem. I checked the permissions and settings of the file which is "unconfined_u:object_r:config_home_t:s0" but I have no idea if this is the right value, running "restorecon" on the file, directory or the whole /home/user didn't change anything.
I've been using Deny Hosts for a couple of years now without trouble. My router forwards SSH calls to host tock on my LAN. My router's internet hostname is michigan. I keep an svn repository on tock and access it through michigan. In this way I can update my repository when I'm at home or away.Just today, however, whenever I try any ssh to michigan, I get a closed connection and find michigan in my hosts.deny file. I delete it, make a successful connection, but then on my next attempt - there I am in the hosts.deny file again.
I've worked around it by putting michigan into my hosts.allow file, but I would really like to know what's going on. I've configured Hosts Deny to lock out IPs after three failed attempts, but it is locking out michigan after one successful connection.
I would like to COMPLETELY block a specific IP address using iptables. I found this one:
Code:
iptables -A INPUT -p tcp -s xxx.xxx.xxx.xxx -j REJECT --reject-with tcp-reset
Will this work? How do I undo the changes later?
I am setting up a iptables firewall on one of our servers, and I would like to block a range of addresses from getting into the system. I am using a script that does a BLACKIN and BLACKOUT methodology for specific addresses. One example is the following:
Code:
$IPTABLES -A BLACKIN -s 202.109.114.147 -j DROP
...
$IPTABLES -A BLACKOUT -d 202.109.114.117 -j DROP
What would be the correct syntax to use if I wanted to block an entire remote subnet from getting into the server?
I want to block some ips permanently ie. even I as the root user cannot unblock these ips without having to format the whole system.
So i thought if some blocking software provided passwords for editing rules and I put a 'junk' password there and so that I can't delete the rules without the 'junk' password which I don't know.
So I examined iptables and I saw that it is a kernel module so there is no use of that since I can probably throw it away.
But the basic question is to block ips and gulp the key.
In our organization we use Static IP addressing scheme(Some departments have DHCP which is not related to this thread). We use Squid as proxy.
We assign each machine its IP address and make entry in our TinyDNS database, and provide those details to users, which they manually enter in their config and then access the network. We assign different range of IPs to different departments. This we consider as the "proper way" for our organization.
But we have found that lot many users are simply guessing some IPs and using them without having any entry in our DNS record. Though this works for some, most of the time we end up having IP conflicts and disorganization in our organizational allocation policy.
So, my question is, How do I block the specific IPs whose entry is not explicitly defined in our DNS record. In other word if the IP 192.168.20.15(lets say he is jack.ourorganization.com) is defined in our DNS, we should allow access... where as if IP 192.168.20.16(this does not translate to any user as it is not defined in our DNS) is not defined in our DNS we should not allow it access to our network.
SElinux is blocking my internet connection and every time when I connect t the internet (pppoe connection) I ge message.
View 2 Replies View RelatedMobloquer starts up at boot and before I've even opened firefox or transmission or anything, mobloquer shows that is has started blocking several outgoing connections as well as ton of incoming connections. I was wondering if the outgoing connections is normal and what's a normal amount of network activity to show up in system monitor when I'm not actively using the internet.
View 2 Replies View RelatedI've small issue with blocking local clients. I mean I've webserver that I want to allow limited number to clients to that let say I've 10 users from 10.5.1.1-10 I would like to block 1-9 and allow only last client to access that webserver . Ive tried the following
Code:
iptables -A -p tcp -i eth1 -d 10.1.1.14 -s ! 10.5.1.10 -j REJECT
iptables -A INPUT -p tcp -d 10.1.1.14 -i eth1 -s ! 10.5.1.10 -j DROP
I'm running a program called Synergy+ to let my keyboard and mouse control multiple computers. One of Synergy+'s features is that clipboard (copy-paste) data is able to be shared, as in copy on one machine, paste onto another. I would like this functionality removed but Synergy+ has no way to disable it. I'm looking for any ideas to block clipboard data from being transferred. Is there a way to block a program from accessing the machine's clipboard data?
View 5 Replies View Related