Why rinetd is working locally but not working remotly

linux-networking

/etc/rinetd.conf
0.0.0.0 443 10.30.224.7 636
allow *

>lsop -i|grep rinetd
rinetd    27099        root    4u  IPv4 2553556       TCP *:https (LISTEN)

Also iptables -L -n returns nothings.

Still, if I try to telnet to localhost (or using the server IP) to port 443 it will work but if I try the same from another machine it will fail with telnet: Unable to connect to remote host: Connection timed out

So, there is something on that port but it does not want to respond.

What am I missing?

Best Answer

"Connection timed out" usually indicates a firewall is in place. If it wasn't the firewall, it would say "Connection refused" or something similar (in case service isn't accessible). Run service iptables stop and if you are on RH based OS be sure to check SELinux and disable it for the time of debugging with setenforce 0.

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Centos – SSH works locally but not remotely

I suspect a change in networking configuration because your MAC address has changed. If you swap out mainboards on an existing Linux installation, the file /etc/udev/rules.d/70-persistent-net.rules will create new entries for your devices and give them new names. So, if you had eth0 and eth1 before, you will now probably have eth2 and eth3. You need to manually update that file after changing network adapters.

Additionally, can you show your firewall rules (iptables -L -n)?

Iptables – Set Up Port Listening And Forwarding

Ok, I found the solution. Turned out, I was not that wrong but something was missing:

sysctl -w net.ipv4.conf.eth0.route_localnet=1

Thanks to Ipor Sircer who pointed out, that the kernel will drop packets with 127.0.0.1 and thanks to this post, that pointed out how to circumvent this restriction.

So, here again the full setup I'm using, if someone needs to do something similar (i.e. setting up port forwarding on a virtual machine to localhost):

sudo sysctl -w net.ipv4.ip_forward=1
sudo iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j  DNAT --to-destination 127.0.0.1:8080
sudo sysctl -w net.ipv4.conf.eth0.route_localnet=1

Of course, change the ports and the interface to your settings. I.e. change --dport and --to-destination AND eth0 in the second last and last command to your interface.

Also make sure every machine can really talk to each other - usually for a virtual machine you need to do some extra set up.

Best Answer

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Centos – SSH works locally but not remotely

Iptables – Set Up Port Listening And Forwarding

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