I use the Weave network plugin on a Docker-Swarm.
I created a docker network with a specific IP-Range, different from the default Weave Network, to which I route from my internal network.
To make the containers even better accessible I use weave to attach DNS names like containername.auto.mycompany.de. Now I want to access those from my company Network. The Problem is, that weave only allows access to the weave DNS from the local host.
Like on one of my swarm nodes i can do:
host foobar.auto.mycompany.de 172.17.0.1
Using domain server:
Name: 172.17.0.1
Address: 172.17.0.1#53
Aliases:
foobar.auto.mycompany.de has address 10.40.13.3
Host foobar.auto.mycompany.de not found: 3(NXDOMAIN)
Host foobar.auto.mycompany.de not found: 3(NXDOMAIN)
But I don't find a way to make the weave container accessible on one of the IP's from this (10.40.130/24) docker network or expose the port to the swarm node.
The only way I can think of, but don't like, is doing something like this:
iptables -t nat -A DOCKER -p tcp --dport 53 -j DNAT --to-destination 172.17.0.1:53
(this does not work, it's just the idea)
Or tamper with the weave script to make it expose the port on start of the weave container.
Does anybody know of a better solution?
In fact setting the rules
iptables -A DOCKER -p tcp -m tcp --dport 53 -j DNAT --to-destination 172.17.0.1:53
iptables -A DOCKER -p udp -m udp --dport 53 -j DNAT --to-destination 172.17.0.1:53
does it. When I first tried that, I simply missed to see, that my request would have come from "outside" the server to work, not from inside to the loopback device.
Still not a pretty solution but it does the job. I'm looking forward to see better solutions from you guys.
(Bounty stands!)
Related
There is a docker container running in bridge network mode. Inside the container, it creates a connection to, say, 10.123.123.1:6666. I'd like to block this connection on host through IPTABLES, something like sudo iptables -I OUTPUT -p tcp -d 10.123.123.1 -j DROP, but it doesn't work. Could anyone help me on this please?
I can't even see this connection on host by command netstat -an, but I can see it inside the container.
I don't have to use IPTABLES, but I can't change the configuration of the docker running.
These packets are going through INPUT & OUTPUT chains in the container's network namespace, and not in the host's network namespace.
All your host network namespace does is forward these packets so you need to alter the FORWARD chain with a rule similar to iptables -I FORWARD -p tcp -d 10.123.123.1 -j DROP. Bear in mind that Docker alters iptables rules which may punch holes in the firewall.
Which container interface does Docker port mapping (-p <host-port>:<container-port>) apply to?
After having read the Docker documentation, I'm not sure what network interface(s) in the Docker container a Docker port mapping like (1) and (2) applies to.
By default a new container is created with two interfaces eth0 and lo, but more can be added.
(1) is shorthand for -p 0.0.0.0:8080:80.
(2) refers to the network interface on the host with IP address 192.168.1.100, and it maps host port 8080 to container port 80, but on what container interface?
(1) -p 8080:80 Map TCP port 80 in the container to port 8080 on the Docker host.
(2) -p 192.168.1.100:8080:80 Map TCP port 80 in the container to port 8080 on the Docker host for connections to host IP 192.168.1.100.
Do (1) and (2) map host port 8080 to container port 80 on ALL container interfaces (0.0.0.0)? If, so where can I see that in the documentation, and can this behaviour be restricted to a specific set of container interfaces?
https://docs.docker.com/config/containers/container-networking/
TCP connections have a single starting point (IP+port) and single end point (IP+port). As such, the port forwarding can only map to one IP address in the container. Specifically, the bridge network interface.
"Can this behavior be restricted to a specific set of container interfaces" doesn't really make sense, then: by the nature of TCP, there's only ever one interface that's being connected to.
If you're worried that things listening on 127.0.0.1 inside the container will be come public, then don't; they won't (and can't).
https://pythonspeed.com/articles/docker-connection-refused/ has a bunch of diagrams that might make this clearer.
Do (1) and (2) map host port 8080 to container port 80 on ALL container interfaces (0.0.0.0)
Not exactly. (1) maps host port 8080 to container port 80 on all host interfaces. (2) maps host port 8080 on host interface with ip address 192.168.1.100 to containers port 80.
Specifically, it does something along (copying from my machine):
iptables -t nat -A PREROUTING -m addrypte --dst-type LOCAL -j DOCKER
iptables -t nat -A OUTPUT ! -d 127.0.0.0/8 -m addrtype --dst-type LOCAL -j DOCKER
iptables -t nat -A DOCKER ! -i <bridge docker interface> -p tcp -m tcp --dport 8080 -j DNAT --to-destination <container-IP-address>
In net:PREROUTING the traffic for dport 8080 is redirected to container IP Address.
I believe you seem to be confused and assume that containers have multiple interfaces. Container has (usually) one interface and is connected to one docker network.
Operating system : ubuntu 16.04 LTS ,here's my problem.
Recently I'm building a application rely on a Redis(Docker) offered data service. A customary way of creating new Redis service is kind of like this:
docker pull redis:latest
docker run -d --name redis -p 6379:6379 redis:latest
Assuming my WAN IP is 201.201.201.201 ,then it should just fine to access Redis via address:201.201.201.201:6379.
However this approach exposes a redis server's port to public network ,even though you can give a supper long password ,potential safety hazard remains.
Since docker do not support port mapping changing within a running container ,I need to shut down the whole docker service ,that takes a long time ,nearly impossible.
Then I'm trying to use IP table mapping instead of creating a docker map ,due to iptables 's flexibility ,theoretically it allows benefits from both sides -- uoload files from wherever else in the world(out side zz) ,but can also close this
iptables -t nat -A PREROUTING -d 172.245.210.199 -p tcp --dport 6379 -j DNAT --to-destination 172.17.0.5:6379
iptables -t nat -A POSTROUTING -d 172.17.0.5 -p tcp --dport 6379 -j SNAT --to 172.17.0.1
But it do not work ,I can't ping container 17.17.0.162
Does anyone knows resolution ,or could propose some other ways to implement this port mapping (such as nginx or caddy?)
Thanks!
What I suggest is to use an assistant container, in this container add port forward for your service container which did not do port mapping:
docker run -idt --link redis -p 6379:6379 alpine/socat TCP4-LISTEN:6379,fork,reuseaddr TCP4:redis:6379
Above container will use --link redis so it can resolve the name of your redis container, and when receive the traffic from host's 6379, it will first forward to assistant container's 6379, then will use socat to forward the traffic to the redis container's 6379, so it works although your service container did not port mapping 6379.
As --link was deprecated, you can also customize your network, as you like:
docker network create my_network
docker network connect my_network redis
docker run -idt --network my_network -p 6379:6379 alpine/socat TCP4-LISTEN:6379,fork,reuseaddr TCP4:redis:6379
I use docker-compose on ubuntu 18 on remote server.
How, with iptables, can i block access from the internet to the docker port and only allow access to it from the localhost of this server?
For instance, i want to block 4150 port for internet. Trying this:
iptables -A DOCKER-USER -p tcp --dport 4150 -j DROP does not block the port - still can access to it from the internet (not from server machine).
How can i block access from internet to all ports that are on the server, but allow only 22,80 ? And keep that ports available from localhost of the server (eg from the server itself) ?
Not the IPTables based solution you're looking for, but a much simpler solution is to only publish to a specific interface, instead of all interfaces. And when that interface is the loopback interface, e.g. 127.0.0.1, you'll only be able to access the port locally. To do this, add the interface to the beginning of the publish spec:
docker run -p 127.0.0.1:4150:4150 ...
Or a similar syntax in the compose file:
...
ports:
- 127.0.0.1:4150:4150
...
As for why the command you tried using didn't work, this needs conntrack to get the original port rather than the docker mapped port:
iptables -I DOCKER-USER -p tcp -m contrack --ctorigdstport 4150 -j DROP
This also changed from -A (append) to -I (insert) because there's a default rule to accept everything in that list.
I've booted up a CentOS server on rackspace and executed yum install httpd'd. Then services httpd start. So, just the barebones.
I can access its IP address remotely over ssh (22) no problem, so there's no problem with the DNS or anything (I think...), but when I try to connect on port 80 (via a browser or something) I get connection refused.
From localhost, however, I can use telnet (80), or even lynx on itself and get served with no problem. From outside (my house, my school, a local coffee shop, etc...), telnet connects on 22, but not 80.
I use netstat -tulpn (<- I'm not going to lie, I don't understand the -tulpn part, but that's what the internet told me to do...) and see
tcp 0 0 :::80 :::* LISTEN -
as I believe I should. The httpd.conf says Listen 80.
I have services httpd restart'd many a time.
Honestly I have no idea what to do. There is NO way that rackspace has a firewall on incoming port 80 requests. I feel like I'm missing something stupid, but I've booted up a barebones server twice now and have done the absolute minimum to get this functioning thinking I had mucked things up with my tinkering, but neither worked.
Any help is greatly appreciated! (And sorry for the long winded post...)
Edit
I was asked to post the output of iptables -L. So here it is:
Chain INPUT (policy ACCEPT)
target prot opt source destination
ACCEPT all -- anywhere anywhere state RELATED,ESTABLISHED
ACCEPT icmp -- anywhere anywhere
ACCEPT all -- anywhere anywhere
ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:ssh
REJECT all -- anywhere anywhere reject-with icmp-host-prohibited
Chain FORWARD (policy ACCEPT)
target prot opt source destination
REJECT all -- anywhere anywhere reject-with icmp-host-prohibited
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
In case not solved yet. Your iptables say:
state RELATED,ESTABLISHED
Which means that it lets pass only connections already established... that's established by you, not by remote machines. Then you can see exceptions to this in the next rules:
state NEW tcp dpt:ssh
Which counts only for ssh, so you should add a similar rule/line for http, which you can do like this:
state NEW tcp dpt:80
Which you can do like this:
sudo iptables -I INPUT 4 -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT
(In this case I am choosing to add the new rule in the fourth line)
Remember that after editing the file you should save it like this:
sudo /etc/init.d/iptables save
CentOS 7 uses firewalld by default now. But all the answers focus on iptables. So I wanted to add an answer related to firewalld.
Since firewalld is a "wrapper" for iptables, using antonio-fornie's answer still seems to work but I was unable to "save" that new rule. So I wasn't able to connect to my apache server as soon as a restart of the firewall happened. Luckily it is actually much more straightforward to make an equivalent change with firewalld commands. First check if firewalld is running:
firewall-cmd --state
If it is running the response will simply be one line that says "running".
To allow http (port 80) connections temporarily on the public zone:
sudo firewall-cmd --zone=public --add-service=http
The above will not be "saved", next time the firewalld service is restarted it'll go back to default rules. You should use this temporary rule to test and make sure it solves your connection issue before moving on.
To permanently allow http connections on the public zone:
sudo firewall-cmd --zone=public --permanent --add-service=http
If you do the "permanent" command without doing the "temporary" command as well, you'll need to restart firewalld to get your new default rules (this might be different for non CentOS systems):
sudo systemctl restart firewalld.service
If this hasn't solved your connection issues it may be because your interface isn't in the "public zone". The following link is a great resource for learning about firewalld. It goes over in detail how to check, assign, and configure zones: https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-using-firewalld-on-centos-7
SELinux prevents Apache (and therefore all Apache modules) from making remote connections by default.
# setsebool -P httpd_can_network_connect=1
Try with below setting in iptables.config table
iptables -A INPUT -p tcp --dport 80 -j ACCEPT
Run the below command to restart the iptable service
service iptables restart
change the httpd.config file to
Listen 192.170.2.1:80
re-start the apache.
Try now.
If you are using RHEL/CentOS 7 (the OP was not, but I thought I'd share the solution for my case), then you will need to use firewalld instead of the iptables service mentioned in other answers.
firewall-cmd --zone=public --add-port=80/tcp --permanent
firewall-cmd --reload
And then check that it is running with:
firewall-cmd --permanent --zone=public --list-all
It should list 80/tcp under ports
Search for LISTEN directive in the apache config files (httpd.conf, apache2.conf, listen.conf,...) and if you see localhost, or 127.0.0.1, then you need to overwrite with your public ip.
Try disabling iptables: service iptables stop
If this works, enable TCP port 80 to your firewall rules:
run system-config-selinux from root, and enable TCP port 80 (HTTP) on your firewall.
this would work:
-- for REDHAT
use : cat "/etc/sysconfig/iptables"
iptables -I RH-Firewall-1-INPUT -s 192.168.1.3 -p tcp -m tcp --dport 80 -j ACCEPT
followed by
sudo /etc/init.d/iptables save
this is what worked for us to get the apache accessible from outside:
sudo iptables -I INPUT 4 -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT
sudo service iptables restart
Set apache to list to a specific interface and port something like below:
Listen 192.170.2.1:80
Also check for Iptables and TCP Wrappers entries that might be interfering on the host with outside hosts accessing that port
Binding Docs For Apache
Disable SELinux
$ sudo setenforce 0