Adding a rule in iptables in debian to open a new port

Question

I am trying to open port 3306 in iptables in my Debian System to allow access to MySQL server  For which I entered this command   root debian    sudo iptables -A INPUT -p tcp --dport 3306 ACCEPT root debian    iptables-save   I entered the new connection and it has been saved in iptables as I can see the new rule in iptables list genereted by iptables-save command   However  this debian system is running on a VM over Windows7 and I m not able to telnet from Windows to this port  Not sure where I am supposed to check for the solution to this problem

User · Answer

About your command line   root debian    sudo iptables -A INPUT -p tcp --dport 3306 --jump ACCEPT root debian    iptables-save    You are already authenticated as root so sudo is redundant there  You are missing the -j or --jump just before the ACCEPT parameter  just tought that was a typo and you are inserting it correctly     About yout question   If you are inserting the iptables rule correctly as you pointed it in the question  maybe the issue is related to the hypervisor  virtual machine provider  you are using   If you provide the hypervisor name  VirtualBox  VMWare   I can further guide you on this but here are some suggestions you can try first   check your vmachine network settings and    if it is set to NAT  then you won t be able to connect from your base machine to the vmachine  if it is set to Hosted  you have to configure first its network settings  it is usually to provide them an IP in the range 192 168 56 0 24  since is the default the hypervisors use for this  if it is set to Bridge  same as Hosted but you can configure it whenever IP range makes sense for you configuration    Hope this helps

User · Answer

I presume that you ve concluded that it s an iptables problem by dropping the firewall completely  iptables -P INPUT ACCEPT  iptables -P OUTPUT ACCEPT  iptables -F  and confirmed that you can connect to the MySQL server from your Windows box    Some previous rule in the INPUT table is probably rejecting or dropping the packet  You can get around that by inserting the new rule at the top  although you might want to review your existing rules to see whether that s sensible   iptables -I INPUT 1 -p tcp --dport 3306 -j ACCEPT   Note that iptables-save won t save the new rule persistently  i e  across reboots  - you ll need to figure out something else for that  My usual route is to store the iptables-save output in a file   etc network iptables rules or similar  and then load then with a pre-up statement in  etc network interfaces

[debian] Adding a rule in iptables in debian to open a new port

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