top button
Flag Notify
    Connect to us
      Site Registration

Site Registration

IPTable: Issue with owner module?

+2 votes
482 views

I have some issue with module (owner) in iptables v1.4.14

Current rule fails:
iptables -t nat -A OUTPUT -o eth0 -p tcp -s x.x.x.x -m owner --gid-owner usergroup -j DNAT --to-destination x.x.x.x:80;
I tried to use numeric gid, it failed too..

But this rule works fine:
iptables -t nat -A OUTPUT -o eth0 -p tcp -s x.x.x.x -m owner --uid-owner user -j DNAT --to-destination x.x.x.x:80;

Is it a BUG or I am missing something?

posted Dec 15, 2013 by Anderson

Looking for an answer?  Promote on:
Facebook Share Button Twitter Share Button LinkedIn Share Button
1. What is the kernel version?
2. Fails how? Please provide more details.

Similar Questions
+5 votes

I want to forward all http traffic coming in from a perticular IP at local port 8080, to 2 particular IP Addresses (port 80). Is it enough to prepend the following in my IPtable

-A PREROUTING -s xx.xx.xx.xx/24 -p tcp --dport 8080 -j DNAT --to-destination xxx.xxx.xxx.xxx:80
-A PREROUTING -s xx.xx.xx.xx/24 -p tcp --dport 8080 -j DNAT --to-destination yyy.yyy.yyy.yyy:80

+1 vote

I wanted to make a white list using the settings below.

iptables -N wanout
iptables -I FORWARD -i `nvram get lan_ifname` -j wanout

iptables -I wanout -m mac --mac-source 01:26:f7:46:71:4b -j ACCEPT
iptables -I wanout -m mac --mac-source d2:37:b5:f2:39:f3 -j ACCEPT

iptables -I wanout -d gamepedia.com -j ACCEPT
iptables -I wanout -d toysrus.com -j ACCEPT

iptables -A wanout -j REJECT --reject-with icmp-proto-unreachable

So the boxes with the MACs specified are exempt from blocking. The domains "gamepedia.com" and "toysrus.com" are accesible to all.

But the problem is that those domains pulls stuff in from other domains using or something, which makes the IPTable block the loading of the website to complete.

How do I deal with that in the best way? I don't want to look up everything they pull in and white list that as well. Also it might change.

Isn't there a way to say "accept all from this domain, even unrelated stuff"?

0 votes

I am trying to queue the packets of a process so I can use libnetfilter_queue to modify them.

I read in the documentation that I should use --pid-owner processid to filter packets of a process and iptables -I

  -j NFQUEUE --queue-num  to add them to the queue.

I read the documentation but I am still confused how to do this. If any one can help me to understand this command I would appreciate it a lot.

0 votes

Consider the following example: you have a router between two networks, and you want to cut off the
router from the outside world using some iptables rules. However, all traffic that is forwarded by the router between the two networks basically is to be ignored by iptables (i.e., the router does not play firewall for any of the two networks).

Currently, if conntrack is loaded on the router, then conntrack -L on the router lists all the connections, not only those to and from the router, but also all connections between the two. Certainly, it takes some CPU cycles for the router to keep track of all the connections. Also, the number of connections that conntrack can take of is limited.

So is there a way to let Linux "bypass" conntrack and maybe other netfilter stuff when it comes to forwarded packets?

+1 vote

Is there a way to find out if there any iptables rules set on a machine ?

There are some indirect ways which will not always work; for example, I know that on most hosts, iptables -S will return the following output (when no iptable rules are set)
-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT

So you can check whether or not the number of output lines is greater than 3 (as an indication of whether or not iptables rules are set). But there are hosts on which there are more chains then these 3; these chains are set by application/services, even without any iptable rules which are set. And after running iptables -F on these machines, iptables -S will still show more than 3 chains, even that there are no iptables rules set in these chains.

So the question is - is there a way to know whether or not netfilter rules are set on a host, regardless of the number of chains ?

...