SIP is a complex (multi ports) protocol and requires a protocol helper (aka ALG). netfilter/conntrack provides a (n in-kernel ALG) SIP helper that you must use. More informations there: Secure use of iptables and connection tracking helpers. Also, port 5061 is usually TLS so can't be snooped by the helper so traffic there still won't work.

Dec 19, 2011 How to configure iptables on Ubuntu - UpCloud The iptables-persistent looks for the files rules.v4 and rules.v6 under /etc/iptables. These are just a few simple commands you can use with iptables, which is capable of much more. Read on to check on some of the other options available for more advanced control over iptable rules. Gentoo Forums :: View topic - iptables - help Dec 04, 2008

Hi, I seem to be having some issues with Centos 4.4 (2.6.9-22.EL) & iptables. I have a VPN server behind my firewall (running centos 4.4) which I want to allow PPTP & GRE to.

The user-space application program iptables allows configuring the tables provided by the Linux kernel firewall, as well as the chains and rules it stores. In this guide, we'll show you some helpful commands for using iptables to secure your CentOS server. iptables-restore -w -n · Issue #440 · firewalld/firewalld

May 11, 2017

Iptables to allow incoming FTP - Unix & Linux Stack Exchange I want to allow incoming FTP traffic. CentOS 5.4: This is my /etc/sysconfig/iptables file. # Generated by iptables-save v1.3.5 on Thu Oct 3 21:23:07 2013 *filter :INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [133:14837] -A INPUT -p tcp -m tcp --dport 21 -j ACCEPT -A INPUT -p tcp -m state --state ESTABLISHED -j ACCEPT -A INPUT -j REJECT --reject-with icmp-port-unreachable -A OUTPUT How to configure iptables on CentOS - UpCloud