1
vote
0answers
15 views

NAT-T set up using 3 linux machines

I am trying to have a simple NAT-T setup using 3 linux machines. Linux1 Linux2(NATdevice) Linux3 (eth0) 192.168.1.51 <--->(eth1)192.168.1.80 & ...
0
votes
0answers
25 views

Routing incoming source IP traffic to a loopback IP issue

I'm wanting to accomplish the following: I have a BIND DNS server setup where it is listening on ANY address and also listening in a BIND config ACL on 127.0.1.1. If there is another way where you ...
0
votes
0answers
16 views

Set source address for incoming packets on a server

I'm developing a UDP reverse proxy for a game server, and so far, everything has gone fine except for one thing - getting the backend server to submit requests to the master server list (run by a 3rd ...
1
vote
0answers
20 views

SNAT with firewall-cmd?

I have an interface with multiple IP Addresses (on CentOS 7), which is in zone "external" (with masquerade on). I want to specify that, if a connectiona attempt to a specific address goes out, to use ...
1
vote
2answers
74 views

ping: unknown host with iptables enabled

I can't ping www.google.com. However I can ping the IP address: ping 74.125.237.142 At first, I thought it is a problem with my DNS settings. But I checked my resolv.conf, hosts, and hostname ...
-1
votes
0answers
19 views

iptables forward too many interface

Can I build a FORWARD rule which gives both an in/out and SRC/DST IP host? I need to create a rule that does the following: PC -> switch (non-mgmt) -> Linux Router (VLAN) -> world: block ICMP $ ...
1
vote
0answers
32 views

How do I write the rule that has an edge server forward a clients request to an internal network server and back?

I have a network situation as follows: -server1:1.1.1.1 -server2:2.2.2.2 -tunnel 10.8.0.0/24 -client: 3.3.3.3 I'm trying to have client IP 3.3.3.3 do an HTTP request from the 1.1.1.1 server. ...
2
votes
1answer
38 views

iptables routing incoming IP to another destination IP question

I have a test setup: server1:1.1.1.1 server2:2.2.2.2 client: 3.3.3.3 I'm trying to have client IP 3.3.3.3 do a HTTP request from the 1.1.1.1 server. However I want the 1.1.1.1 server to pass this ...
1
vote
2answers
107 views

Drop TCP packets and prevent TCP retransmission

I have an application that sends TCP data to a server. My server is made to intentionally drop the packets sent by the application, and as a result the client retransmits the packets. I need to ...
4
votes
2answers
67 views

Redirecting loopback traffic through a router

For some tests purposes, I am running multiple socket-based applications on one machine and want to simulate "real" network conditions between them. I thought the simplest would be to redirect all ...
0
votes
0answers
42 views

How can I use 0.0.0.0/0 in ipset hash:net,port?

Right now, if I do ipset a ansible_allowed 0.0.0.0/0,tcp:22 I get ipset v6.19: The value of the CIDR parameter of the IP address is invalid and instead I have to add 0.0.0.0/1,tcp:22 ...
3
votes
1answer
37 views

Which network services depend on the “accept related input” iptables rule?

Background I am setting up a firewall for a webserver and was wondering if it would be a good security meassure to even reject RELATED input traffic and only except established connections by ...
2
votes
1answer
90 views

In iptables, what is the difference between targets DNAT and REDIRECT?

More specifically, is -A PREROUTING -i $INT -p $PROTO --dport $PORT -j REDIRECT --to-ports $NEWPORT equivalent to one or both of these? -A PREROUTING -i $INT -p $PROTO --dport $PORT -j DNAT ...
1
vote
0answers
121 views

Packets sent through TUN interface not routed

I have a C program attached to a TUN interface. In my C program, I'm building packets and writing them to the TUN interface. Now to check if packets are really sent from my TUN interface I use ...
1
vote
0answers
81 views

How do I control ip routing in the new firewalld?

I have the following scenario: Our fedora server is connected to the internet on eth0 and has a second nic, wlan0 acting as an access point. The purpose of the access point is to provide a connection ...
1
vote
1answer
77 views

Configure NAT filtring behavior with iptables

I'm using this rule to configure SNAT: iptables -t nat -A POSTROUTING -o eth1 -j SNAT --to-source 193.49.142.107:4000 I want to specify a rule to filter out packets not destined to the internal ...
1
vote
1answer
142 views

Randomize external port when doing NAT with iptables

I want to configure a NAT behavior different from the default one implemented by iptables. In this example: iptables -t nat -A POSTROUTING -o eth1 -j SNAT --to-source 193.49.142.107:2000-400 The ...
1
vote
0answers
73 views

Local Client/Server communication using TUN interfaces

I want to establish a local communication between a client and a server using TUN interfaces. The client program will be attached to interface TUN1 and we suppose that it has IP address @IP1. The ...
1
vote
1answer
82 views

How do you route to secondary interface on the same physical port?

INTERNET<->(wan)BRIDGED_DEVICE(lan)<->ETH_ROUTER<->LAN Problem: Need to access web server on BRIDGED_DEVICE's LAN from INTERNET via ROUTER (BRIDGED_DEVICE web server cannot be accessed form ...
2
votes
1answer
139 views

iptables - add rule for interface before it comes up

Right now I'm using /etc/rc.local to add some iptables rules on my Linux router on boot however some of the rules aren't added. I assume this is because the interface hasn't come up yet. This is what ...
1
vote
1answer
41 views

Creating a virtual interface to always access a DHCPed interface with the same ip

I have an interface that on connect always gets a new IP. So I want to create a virtual interface with a static IP that "relays" everything over the physical interface. This would be useful to bind ...
1
vote
0answers
87 views

CPU usage by kernel modules, routing and forwarding rules

I have a system with a loopback kernel module installed. Through a bunch of routing and iptable rules, packets coming out of the loopback interface are sent over an ipsec tunnel. I am seeing that ...
2
votes
2answers
226 views

Bonding two broadband connections to serve LAN as a gateway

I need to increase the connectivity and speed of the Internet to my LAN users. These are the things I have in my hand to do so. PC with 3 NICs 1 for LAN and 2 for routers 2 broadband connections ...
1
vote
1answer
37 views

Redirect packets and save the content to disk

I want to reroute a connection just like rinetd does but save the client and server messages. Is there any tool like this out there ? I'm using Debian.
1
vote
0answers
476 views

Port redirection on loopback with IP other than 127.0.0.1

I want to redirect port 80 on the loopback network interface so that accesses to that port actually go to port 8080. I tried using the following command, but it only works if the application is ...
1
vote
0answers
186 views

iptables server behind NAT accessible from outside as well as inside the nat

I have 2 machines with a KVM running on each machine - so two kvms with the below networking Host 1: 192.168.10.100 (eth2) 10.10.100.1 (virbr1) KVM 1 (NAT with Host 1): 10.10.100.128 (eth0 ...
0
votes
2answers
150 views

What is the simplest method to redirect traffic using either a proxy or iptables?

I need to redirect all incoming traffic on port 7777 to a specific destination_ip:port. I have about 40 Litecoin (scrypt) mining rigs that I have to manually reconfigure each time I'd like to switch ...
2
votes
0answers
41 views

iptables drop length and TTL condition doesn't work

With iptables utility on Linux host need to create mini firewall. I need to drop all incoming connections with package length greater than 722 AND TTL greater than 22. Need exactly AND. Drop only if ...
5
votes
1answer
244 views

Skip routing via `lo` interface for outgoing packets

Introduction I have following load balancing configuration: 10.0.1.31 - lb 10.0.1.35 - virtual IP 10.0.1.32 - node1 (tomcat + mysql) 10.0.1.33 - node2 (tomcat + mysql) I'm using keepalived which ...
4
votes
1answer
154 views

Can iptables be used to monitor TCP timeouts/resets system-wide?

I'm trying to determine if an application's connection to a database is internal to the application or due to a networking event. This seems like something netfilter would have system-wide visibility ...
0
votes
0answers
140 views

What is wrong with these iptables' rules?

The following is what I got after googling: iptables -A INPUT -i lo -j ACCEPT iptables -A OUTPUT -o lo -j ACCEPT #allow loopback access iptables -A OUTPUT -d 255.255.255.255 -j ACCEPT #make sure you ...
1
vote
1answer
31 views

What is the meaning “MAC MISSMATCH”? [closed]

I have every day in the log the few lines start with: MAC MISSMATCH:IN=vlanXX OUT= MAC=ff:ff:ff:ff:ff:ff:bc:ae:c5:da:70:a6:08:00:45:00:00:4e SRC=xx.xx.xx.xx DST=xx.xx.255.255 LEN=78 TOS=0x00 ...
1
vote
0answers
23 views

How can I use iptables to block certain processes from accessing the network? [duplicate]

I can set the processes to run under special uid's and use the technique from this SF answer: -A OUTPUT -m owner --uid-owner 400 -j DROP ...But are there any other ways to blacklist based on the ...
1
vote
1answer
137 views

Masquerade not working sometimes

I have an issue with private network traffic not being masqueraded in very specific circumstances. The network is a group of VMware guests using the 10.1.0.0/18 network. The problematic host is ...
1
vote
1answer
89 views

tcp/ip - trigger action or event after period of no network activity on certain port(s)

Is it possible, perhaps using iptables or one of the wrappers/frontends to iptables, to trigger an action or run a script after a certain period of time has elapsed with no network activity on a ...
0
votes
3answers
79 views

iptables rules - input and output

I'm new with Linux and iptables. I have a Ubuntu Server distro (12.04) on a PC which has 2 network interfaces (eth0 and eth1). I also have 2 laptops, one is plugged to eth0 and the other to eth1. ...
1
vote
1answer
132 views

Why aren't my iptables rules appearing in the relevant list after reboot?

I am trying to write two persistent NAT rules, which I save via iptables-save > /etc/iptables.ipv4.nat, and restore upon reboot via pre-up iptables-restore < /etc/iptables.ipv4.nat in my ...
3
votes
1answer
71 views

Did this tutorial block pings to my server?

I am a programmer teaching myself linux admin stuff. I followed this tutorial to setup a firewall on a VPS. As a part of that tutorial, I block all traffic except for web traffic and SSH traffic. I ...
1
vote
1answer
27 views

Will this open up a non-standard port to ssh?

I am following tutorials on iptable and want to allow ssh traffic on my non-standard SSH port = YYY. I think this is how you do it, but want to double check so I don't lock myself out of my server. ...
0
votes
1answer
71 views

What does the last column in this IP table mean?

From a tutorial, I run $sudo iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT $ sudo iptables -L and get target prot opt source destination ACCEPT ...
0
votes
2answers
169 views

What is the default action for incoming packets that don't match explicit iptables rules?

CentOS 5.x I'd like to understand what is specifically happening to incoming packets that don't explicitly match rules in my iptables chains. Is the default action to reject them? Or drop them? ...
2
votes
1answer
81 views

Forward a host's network traffic to another host with the exception of SSH traffic

I am trying to redirect all the network traffic received in a old host to a different host. For that I created two new rules with iptables on the old host: echo 1 > /proc/sys/net/ipv4/ip_forward ...
0
votes
1answer
226 views

Some packets are flagged as INVALID by iptables

I configured a proxypass rule in order to redirect requests from the port 443 to a JBoss server running on port 8080. All works fine except some 503 errors in the Apache log, around 10 per day: In ...
2
votes
1answer
361 views

iptables: redirect local request with NAT

I'd like to redirect local requests to port which is translated with NAT. I have following rules: iptables -t nat -A PREROUTING -p tcp --dport 9020 -j DNAT --to 10.0.3.11:80 however request coming ...
1
vote
1answer
72 views

How to measure the time a packet spends on the system(router)?

I have a streaming system and one if its components is a router/firewall. I'm using iptables for setting the required behaviour on the router. I'm having performance issues in forms of a constant ...
0
votes
0answers
25 views

Routing Application through different network interfaces [duplicate]

I have two interfaces on a server, let's call them eth0 and eth1. The underlying server is running CentOS 6.5 I would like to be able for some application to use eht0 while some others use eth1. ...
2
votes
1answer
89 views

Internet sharing with iptables: choosing which connection to share

I have a computer with two network devices (eth0 and wlan0), both connected to the internet (two different connections/isp). I'm trying to share the connection of wlan0 to another computer connected ...
1
vote
0answers
79 views

setting up a local VoIP to use as a Wifi Headset

I had this idea of using Wi-fi in a vehicle to connect my cell to the car call handler.Just as it works with bluetooth nowadays. Just to demonstrate that such a thing is possible , i had three Linux ...
0
votes
0answers
629 views

Use iptable do redirect all the HTTP traffic to localhost

I use a Linux machine as WLAN Router with the help of hostapd and udhcpd. There's also an Apache web server installed on the same machine. Now I want to redirect all the traffic which comes through ...
0
votes
1answer
403 views

iptables couldn't load target allow

I am using the command below to allow all traffic from hosts on my internal network but it says "iptables v1.4.18: Couldn't load target `ALLOW':No such file or directory". What is the problem here? ...