Retrieving original destination from iptables after REDIRECT

I'm writing an application proxy for generic use. I want to use this as a transparent proxy, where my original plan is to use iptables with a REDIRECT rule forward all connections to my...

To check linux firewall status without root privileges

I'm writing a bash script which will check if the local firewall is up, and based on the status, perform some operation. Ideally, within my script I would do: su root...

Cloning and forwarding packets to multiple IP addresses

I'm trying to forward all incoming TCP packets to multiple IP addresses. Setup: A - 10.10.10.10 B - 10.10.10.11 C - 10.10.10.12 D - 10.10.10.13 I want B, C and D to receive (on port 8000) all...

Can't access jenkins remotely

I installed jenkins on my remote server. If I do at the server: wget http://server.url:8080 I get the page without any problem. At my computer, I get that: --2014-01-09 14:11:33-- ...

how to test user space tcp/ip stack?

I am working on a user space tcp stack (mostly just for fun) and I am having some trouble testing it against the unix tcp stack. Currently the only form of testing is done via unit tests. However,...

Why does the iptables connection limit not work?

this is my iptables, everything works fine, except that these IP's with more than 20 connection wont get blocked. iptables -F iptables -X iptables -I INPUT 1 -i lo -j ACCEPT iptables -I INPUT 2...

What is the best practice of docker + ufw under Ubuntu

I just tried out Docker. It is awesome but seems not work nicely with ufw. By default, docker will manipulate the iptables a little bit. The outcome is not a bug but not what I expected. For more...

How to identify orphaned veth interfaces and how to delete them?

When I start any container by docker run, we get a new veth interface. After deleting container, veth interface which was linked with container should be removed. However, sometimes it's fail (...

Cannot ping ClusterIP from inside the pod and DNS is not working for external domains like google.com

I have installed Kubernetes on Bare-metal/Ubuntu. I am on 6b649d7f9f2b09ca8b0dd8c0d3e14dcb255432d1 commit in git. I used cd kubernetes/cluster; KUBERNETES_PROVIDER=ubuntu ./kube-up.sh followed by...

Service located in another namespace

I have been trying to find a way to define a service in one namespace that links to a Pod running in another namespace. I know that containers in a Pod running in namespaceA can access serviceX...

Docker - No route to host

When i try and connect to a port from within my container to another container, i am unsuccessful and get, [email protected]:/opt/f5massupgrade# curl -v https://172.17.0.1:6379 * Rebuilt URL to:...

Apache Kafka - DNS resolution failed for url in bootstrap.servers (Failed to construct kafka producer)

I have a problem to construct kafka producer with hostname. Here's what I did. I set the host.name, port config to server.properties listeners=PLAINTEXT://192.168.0.102:9092 port=9092 ...

Can't install Kubernetes on Vagrant

Use this guide to install Kubernetes on Vagrant cluster: https://kubernetes.io/docs/getting-started-guides/kubeadm/ At (2/4) Initializing your master, there came some errors: [[email protected] ~]#...

How to connect vEthernet (DockerNAT) with Ethernet0 interface?

I installed Docker on Windows 10 with Hyper-V. And the virtual network interface named vEthernet(DockerNAT) is generated. Below are network interfaces of my Windows 10 computer. >...

K8s NodePort service is “unreachable by IP” only on 2/4 slaves in the cluster

I created a K8s cluster of 5 VMs (1 master and 4 slaves running Ubuntu 16.04.3 LTS) using kubeadm. I used flannel to set up networking in the cluster. I was able to successfully deploy an...

Enable https on Node-Express App on AWS EC2

I have a node Express app running on an AWS EC2 Instance. I am able to run the server and connect to the express app using http://ec2-xx-xxx-xxx-242.us-west-2.compute.amazonaws.com But when I use...

docker build fails with "address already in use"

docker build fails with "address already in use" # docker build . --no-cache Step 1/23 : FROM python:3.6 ---> 8256ec07b2ad Step 2/23 : ENV PYTHONUNBUFFERED 1 ---> Running in...

Cannot access K8s dashboard after installation of kubeadm-dind-cluster

I am using kubeadm-dind-cluster a Kubernetes multi-node cluster for developer of Kubernetes and projects that extend Kubernetes. Based on kubeadm and DIND (Docker in Docker). I have a fresh Centos...

Dubbo service startup error:Error creating bean with name 'userServiceImpl' nested exception is org.I0Itec.zkclient.exception.ZkTimeoutException

I configured dubbo, using the registry zookeeper, when I start the service, I get an error. = I modified the timeout to 10000 and the error has not changed. I turned off the firewall in the...

Postfix not changing port 25 to 587

I use digital-ocean hosting and ubuntu 16.04, I install postfix and use smtp to send outgoing mail, This is step i do : Change Firewall Setting $ sudo iptables -A OUTPUT -p tcp --dport 587 -j...

Why Docker NAT iptables has RETURN in first row?

Hello StackOverflow users. Now I'm studying docker nat network especially in iptables. I executed docker command like below. Make it to accessible from remote server computer. docker run -d -p...

Print HTTP packet data from inside Kernel Module

I am trying to write a kernel module that will dump all the HTTP packet data to dmesg. I registered a nf_hook in POST ROUTING (tried also hooking OUTPUT table), and printing all the packets which...

cannot create directory ‘/proc/sys/net/bridge’: No such file or directory

I want to install kubernetes on centos 7. I have installed kubeadm and use kubeadm to install kubernetes. kubeadm init error: error execution phase preflight: [preflight] Some fatal errors...

bridge-nf-call-iptables and bridge-nf-call-ip6tables disabled on WSL2

Running docker info in WSL2 (both on ArchWSL and Ubuntu 20.04) I get the following warnings: WARNING: bridge-nf-call-iptables is disabled WARNING: bridge-nf-call-ip6tables is disabled Both...

Opening a specific port in Oracle Cloud - Ubuntu 18

The above one seems like an easy question, but believe me I have tried multiple methods but all seems to be in vain For example : Port is 8080 1st - I followed many oracle docs and tried opening...

How to fix kube-proxy Unknown proxy mode "", assuming iptables proxy issue?

I'm new to K8s and struggling with some problems with kube-proxy. I have a service that needs to expose the deployment. Everything seems correct but it does not expose it. I found the problem in...

Docker on AWS ElasticBeanstalk: "host.docker.internal: host-gateway": Connection refused. Iptables issue?

So I have a multicontainer project running on AWS ElasticBeanstalk (latest Docker platform). The containers share the same bridge network since they need to be able to communicate with each other...

How to delete calicoctl and iptables (created by calico installation) from my k3s

I have a K3s setup with calico pods [calico-node- & calico-kube-controllers-] running. On uninstalling K3s, calico pods get deleted but I see that calicoctl and iptables -S commands still running...

Unable to reach Jenkins Pod from outside of kubernetes cluster under Metallb

I have a Kubernetes cluster that is running a Jenkins Pod with a service set up for Metallb. Currently when I try to hit the loadBalancerIP for the pod outside of my cluster I am unable to. I also...

php -S 0.0.0.0:8000 command can't do "Listening"

I have a strange problem, that I can't spin up a php server on my machine. I just want to access my php app remotely. Firstly I have root access on server, and using ufw for port management. (It...