All Questions
32
questions
0
votes
0
answers
132
views
How to block all connections on all ports using iptables?
I am trying to protect myself from ddos and limiting all users with more then 5 connection request to connect to my server.
I am trying to use this one, but it is not working, it actually blocks even ...
- 1
0
votes
1
answer
129
views
How to exclude 1 ip from iptable rules?
I want to block all ip's with > 200 connections to access my server with this rule:
iptables -A INPUT -p udp --dport 100:65535 -m connlimit --connlimit-above 200 -j REJECT
but at the same time I ...
- 1
0
votes
0
answers
71
views
Script that will scan for number of connections and ban those above 100
since I lately have some DDOS attacks, i need help in creating the script that will do following:
-Screen the IPs on all ports with total number of connections using netstat
-Ban all IP's that are ...
- 1
-1
votes
1
answer
1k
views
How to redirection traffic between interfaces on ubuntu 18.04
i have server that has two interfaces (enp1s0 : 192.168.1.10 and enp2s0 : 10.20.30.30),
enp1s0 is public interface that we can connect to server with it and enp2s0 is private and isolate interface. on ...
1
vote
0
answers
18
views
ufw differentiates block-and-log from unmatched log
I insert block rules using this kind of statements
sudo ufw insert 1 deny log from 45.136.228.230/24
I have a few hundreds of such deny-log rules.
ufw will block the IP and log the event. However, ...
- 689
2
votes
0
answers
3k
views
How to mirror traffic on one interface to another?
I'm basically trying to implement a tap-interface on wlan0 interface (Ubuntu 18.04), i.e., mirror every packet going through wlan0 (incoming and outgoing) to another interface (tap0).
I've got tap0 up ...
- 21
1
vote
1
answer
1k
views
UFW not blocking traffic to microk8s cluster
I successfully deployed k8s pod with service of type NodePort in microk8s cluster. Now when I enable ufw and try to deny incoming traffic to the exposed port 31001 using command ```ufw deny 31001``` , ...
0
votes
1
answer
7k
views
Ubuntu 18.04 route delete permanently
I want to delete a route permanently on Ubuntu 18.04.
The route is the following,route -n:
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
....
0
votes
0
answers
90
views
Port forwarding with 18.04.4 LTS
i have 1 pc running ubuntu 18.04.4 LTS.
this pc has 2 network cards:
enp37s0 (onboard gigabit nic) and enp38s0 (additional pcie gbit nic).
enp37s0 is connected DIRECTLY to the internet by cable ...
1
vote
1
answer
3k
views
-bash: echo: write error: No such file or directory
I am trying to log iptables actions so I can trouble shoot why a FORWARD rule isn't working and I need to run this command:
echo ipt_LOG >/proc/sys/net/netfilter/nf_log/2
this is after loading ...
- 36.9k
0
votes
0
answers
164
views
Can not ping from one node to another while both nodes connected via an ethernet cable
I have two ubuntu machines each with two physical NICs.
I am trying to create a private network between two of them connecting of one node's NIC with the other node's NIC.
In Node 1 when I run
...
- 11
2
votes
0
answers
8k
views
getting error problem running iptables when checking ufw status
when I check ufw status on ubuntu I get the following error.
ufw status
[sudo] password for rock:
ERROR: problem running iptables: iptables v1.6.1: can't initialize iptables table `filter': Table ...
- 363
0
votes
0
answers
159
views
VSFTPD connect from external IP
I have VSFTPD installed on my Ubuntu 18.04 LTS, cant connect from public IP. Here is my config:
listen=YES
listen_ipv6=NO
anonymous_enable=NO
local_enable=YES
write_enable=YES
local_umask=022
...
5
votes
2
answers
1k
views
How to respond to sshd brute force attacks
I recently received a notification from OSSEC HIDS that warns me about a SSHD brute force attack.
Below I report the whole message for the sake of completeness:
OSSEC HIDS Notification.
2020 Mar 03 ...
- 1,667
1
vote
1
answer
2k
views
How can I remove an iptables rule?
I would like to temporarily add the following iptables rule to see if allowing inbound traffic on port 5000 I will be able to connect to my docker container and the web server running within it:
$ ...
- 1,667
2
votes
2
answers
976
views
IP Table rules to swap traffic on two interfaces
The Issue:
I have two interfaces, vlan.202 and tap0. vlan.202 is my VLAN for VPN clients and originally I just used to tunnel all my VPN clients onto a random subnet and have them share my host IP, ...
1
vote
2
answers
1k
views
ubuntu 18.04 torrent seeding problem
I wanted to get my firewall working, and I used:
sudo ufw enable
after that my torrent client stopped seeding, my /ets/nginx folder disappeared and I actually don't even know what happened... so I ...
- 33
3
votes
1
answer
5k
views
Adding manual iptables rules to UFW
I have a use case that needs iptables' ability to restrict a rule to a group id (--gid-owner). Ufw doesn't have support for this in its rule syntax.
From my experiments and reading online (e.g. UFW ...
- 131
2
votes
0
answers
3k
views
How to enable IPTABLES tracing on ubuntu 18.04 server
Ive found this simple straightforward way to trace what Iptables is doing on my kubernetes/calico cluster
https://www.opsist.com/blog/2015/08/11/how-do-i-see-what-iptables-is-doing.html
Nor ipt_LOG, ...
1
vote
0
answers
81
views
Iptables forwarding all ports with certain destination ip address across network interfaces
I have a slightly complex question about iptables.
So I have two network interfaces:
ens5
eth0
I want to route all incoming traffic from eth0 that has an ip in the CIDR block (10.0.0.0/16) to ens5....
3
votes
1
answer
2k
views
iptables owner module not found - match error "No chain/target/match by that name"
This is a fresh copy of ubuntu on my nVidia Jetson Nano, and I am trying to add the following rule to block network access for user 1001.
sudo iptables -A OUTPUT ! -o lo -m owner --uid-owner 1001 -j ...
- 11.3k
1
vote
1
answer
460
views
Make ufw follow iptable rules
I have a bunch of configuration in ufw that I want to avoid porting to iptables (unless there is a easy way to export from ufw and import in iptables). Simplicity of ufw etc. being the reason.
Now I ...
- 385
0
votes
1
answer
455
views
vpn has no internet after upgrading to 18.04
Resently,i upgrade my ubuntu 16.04 server to 18.04
but after upgrading ,my (Cisco anyconnect,pptp) vpn servers have no internet access...
Can anyone help me?
- 665
0
votes
1
answer
1k
views
iptables rules applied multiple times
I had a very simple set of iptables rules on a newly installed system:
$ sudo iptables -L
Chain INPUT (policy DROP)
target prot opt source destination
ACCEPT all -- ...
- 285
1
vote
0
answers
404
views
iptables rules randomly change - ubuntu 18.04
I have a simple set of iptables rules which start on boot a script in /etc/network/if-pre-up.d/:
#!/bin/sh
iptables-restore < /etc/iptables.rules
exit 0
Similarly I have a script in /etc/network/...
- 285
2
votes
0
answers
3k
views
Wired Connection not working on 18.04(LTS). Please Help
$ ifconfig
enp0s25:
flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
ether 28:d2:44:44:0a:1c txqueuelen 1000 (Ethernet)
RX packets 13959 bytes 1516430 (1.5 MB)
RX errors 0 ...
26
votes
5
answers
150k
views
Iptables reload/restart on Ubuntu
I have problem with iptables on Ubuntu 18.04 before that I used to use with Centos 7 and Red Hat and I can simply restart with
systemctl restart iptables
but on Ubuntu it does not work. I could not ...
- 361
0
votes
1
answer
1k
views
how to install ip_tables and ip6_tables modules in ubuntu 18.04 kernel 4.4.0?
I'm trying to upgrade from 16.04 to 18.04. I use FireHOL, but FireHOL can't install in 18.04 server, evidently because there are no ip_tables.ko or ip6_tables.ko kernel modules in /lib/modules/4.4.0-...
- 121
1
vote
0
answers
571
views
iptables rule that uses state
I tried the command conntrack -E and it returns nothing on Ubuntu 18.04.
Someone told me that I have some iptables rule that uses state stuff.
So I set iptables rule such as below:
iptables -A ...
- 163
3
votes
1
answer
2k
views
conntrack shows no result
I tried the command conntrack -L and it returns 0 flow entries have been shown on Ubuntu 18.04.
And conntrack -E doesn't display nothing.
I also tried to load the module by modprobe nf_conntrack_ipv4,...
- 163
2
votes
1
answer
2k
views
How to allow DNS lookup with iptables on Ubuntu 18.04 server
I'm using Ubuntu 18.04 Server and trying to make a router.
When I execute the following iptables script (which worked just perfectly on Ubuntu 16.04), the DNS lookup from command line stops working. I ...
1
vote
1
answer
3k
views
fwmark routing policy with netplan
I'm migrating a legacy Debian setup to a new Ubuntu setup. I have previously set, in /etc/network/interfaces:
post-up /sbin/ip rule add fwmark 1 table table.tunnel
pre-down /sbin/ip rule del fwmark 1 ...
- 13