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Questions tagged [networking]

Networking refers to the technologies and techniques that enable the interconnection of devices and applications allowing them to communicate electronically.

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Can firewall rules be applied to internal GCLB?

tl;dr We're experiencing issues with services behind internal Google Cloud Load Balancer not being able to reply when response is over a certain size. Upon some tcpdump'ing and wireshark'ing, it ...
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2answers
16 views

Created AWS EC2 instance from snapshot AMI, eth0 is missing after startup

I recently created a new EC2 from a snapshot of our Production EC2. The machine started up fine, and I can ssh in, however - cannot access via anything else. No WWW, nothing. Upon further inspection ...
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OpenVPN/OpenWRT/TP-Link TLWR1043ND: How to configure OpenVPN on this router to get access to connected devices only over the WAN interface?

I have the following problem: There are two networks, network X and network Y. In network X is an OpenVPN server. A TP-Link router (see the model in the topic) should be connected to network Y only ...
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how to set outbound traffic for floating ip linux

I am using Heztner server for running my application, which owns IP as 95.216.167.191. Then I added a floating Ip which was 159.69.100.75. my network interface looks like that # interfaces(5) file ...
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1answer
33 views

KVM: Hosts with private and public IPs

We have a small block of static IPs (e.g. 203.0.113.0/29). We currently only use 203.0.113.2 for a mail server. We'd like to add some other public servers, and if possible would like to have them ...
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How do I expose a webserver on my LAN when I don't have a direct connection to the internet [on hold]

My main router is running OpenWRT. It's behind a NAT (that I don't control) so I can't directly expose it to the internet. I have it connected through a Wireguard tunnel to a server in the cloud. I'm ...
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9 views

fial2ban0.9.7 crashing when system.log rotates on macOS10.10.5

I'm trying to install fail2ban0.9.7 (https://github.com/fail2ban/fail2ban/) on a Mac running macOS10.10.5 Yosemite. It is a great program that I run perfectly fine on Unix, Linux and macOS10.6. But ...
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1answer
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Forwarding traffic from a host to a host's container

I have two hosts in a network 192.168.0.0/24: Host A 192.168.0.15 Host B 192.168.0.13 And there is a remote ssh tunnel from B to A: ssh -R 192.168.0.13:8080:192.168.0.15:8002 192.168.0.13 -N and ...
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Why cannot connect TvHeadend IGMP connection in Alpine Linux?

I want to know about alpine linux and IGMP config for TvHeadend, especially when I use multiple nic. I have 4 NIC 1G + 1G = bond0 : use for external service and internet connection 1G = enp1s0 : use ...
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1answer
38 views

Can a router route local traffic through the WAN side to an AP bridge via VLANS on a switch?

I've been researching VLANs and advanced network setups, and I'm wondering if this could work. WAN | Switch (VLAN and QoS for ISP) | \ Gateway router Router(AP bridge mode) | ...
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1answer
24 views

Proxy setup between a private and public

I have two servers: Private Server with IP: 172.16.0.2 Public Server with 172.16.0.3 (private IP) and x.x.x.x (public IP) What I want to achieve is: Incoming communications to Public IP (x.x.x.x) ...
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1answer
44 views

Two similar services, two IPs, one server?

I'm running a CentOS 7 box. On this box I have two services which should both be exposed using port 443 for HTTPS traffic. Using a reverse proxy is no option, one service cannot be reconfigured to ...
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Networking bits to number of subnets [duplicate]

How does one use the value of networking bits of a class A address to find the number of subnet bits and host bits? For example, with a subnet mask of /22, what would be the process of finding the ...
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Can anyone explain what this packet capture log means?

I'm setting up a replacement network gateway and everything is working except I can't reach 1 address in 1 of the subnets... All other addresses in the subnet 192.168.251.0/24 are reachable except 192....
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1answer
42 views

Preventing a server from accessing parts of the network

I did a preliminary search and was unable to find an exact / similar question. I'm configuring a server in our network, in order to give SSH access to a normal user from a third party. I'm trying to ...
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Bypassing a Load Balancing Packet Marking setup for Rate Testing on Centos 7

Trying to Bypass a load Balancer Our system has directs network traffic into a three way load balancer across three cellular modems in normal operation. We use a program called speedtest_cli that ...
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0answers
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Any pcap filter for getting DHCP ACK requests? [closed]

I need it for a program and I just spent the last 2 hours searching for any filter for getting DHC ACK(but found anything else besides it) EDIT:I'm doing on C so no wireshark or anything else.tcpdump ...
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30 views

Windows is listening on addresses never assigned

I have a Windows 2016 server used for development. Thus I have quite a lot of virtual switches and multiple addresses assigned to physical and logical network interfaces. But now I am encountering the ...
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1answer
19 views

Correct way of setting up network teaming for maximum throughput in Windows Server

We have a backup server with 4x1GB NICs. All 4 NICs are configures as a single Team (Switch Independent, Dynamic). NIC 1-2 are connected to SW01, NIC 3-4 are connected to SW02 and the switches are ...
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0answers
23 views

IPv6 prefix delegation [migrated]

I'm a complete noob at IPv6, but have some practical experience of IPv4 (just because I had to deal with it). My home router is behind CGNAT so they don't offer public IPv4 addresses, but I'd asked ...
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1answer
21 views

connecting to a FTP by TLS fails from one client, but succeeds from the other

Trying to connect from client2 using the following string works: client2@client2 curl -v --ssl -u 'user:password' ftp://www.example.com:21 * Rebuilt URL to: ftp://www.example.com:21/ * Trying 192....
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20 views

Zenmap identify connected devices to switch

I'm trying to do a "map" of my company's network to see all of its devices (switch, router... ). After some research, Zenmap (GUI of Nmap) semmed to be a good tool. But when I scanned the network on a ...
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Snort is detecting ICMP even though echo request was disabled

I am performing ICMP flood using Hping3 on Kali Linux. And to detect and prevent that flood by using Snort and Swatch. I want to get alert Snort for possible ICMP flood request and will notify me by ...
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3answers
51 views

why linux assigns ephemeral ports out of its range

I have a server running mysql, ssh and other services. I want to see the range for ephemeral ports available for the OS running: cat /proc/sys/net/ipv4/ip_local_port_range which returns 32768 - ...
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0answers
25 views

bypass network and route directly to server

We have client Macs who utilize a 10GbE adapter to reach our internal network as well as our CentOS 7.4 SAMBA server. The topography from server to client is as follows: The Server is connected over ...
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0answers
8 views

Firewall rules for WebRTC and STUN

I'm trying to get a WebRTC service running, through a corporate firewall. The service works on the local network, but it appears that the firewall is stopping it from working globally. I'm using a ...
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0answers
8 views

Force a path to proxy for 443 traffic. Win 2008 R2

I'm likely thinking about this in completely the wrong way but any guidance is hugely appreciated. I have a requirement to connect from my internal web server to an external DB instance in order to ...
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0answers
43 views

Can you have subnets without network interface? [closed]

When I installed Docker, it automatically creates a docker0 bridge network, which, from what I understand, is simply a private subnet on my machine. When I run ifconfig, I see the docker0 network ...
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1answer
23 views

HP network scanning query

I'm having trouble getting computers (both Windows and Mac) to scan from an MFD to the computers in question. The printer can be seen, added, and printed to from the network. Scan to email works ...
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1answer
33 views

My /etc/resolv.conf is getting reset every time i restart the network

This is my /etc/resolv.conf on CentOS 7: # Generated by NetworkManager search example.com nameserver 10.0.2.3 ~ This is my /etc/sysconfig/network-scripts/ifcfg-eth0 DEVICE=eth0 ...
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2answers
403 views

Debugging DNS resolution error

I'm debugging a DNS resolution error for the domain auth.otc.t-systems.com with Cloudflare's server, but got stuck. The strange thing is that the lookup succeeds/fails depending on the machine that ...
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0answers
35 views

Need information about Network Monitoring Tool [closed]

Recently our networking team at HQ deployed a network monitoring tool to monitor routers, servers etc. which monitors node in real-time and gives an audio alarm when a node gets down. But they didn't ...
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1answer
33 views

whats secure_mode (miniupnpd.conf)

I am trying to set miniupnpd (UPnP server), but please point out if you understand miniupnpd.conf secure_mode. When set to secure_mode = yes, miniupnpd will assign the IP address of the local network ...
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Server with two NICs behind Ubiquiti ERX, connected to two separate private company networks with possible similar address spaces

We have a Ubuntu 18.04 Server running a web application that needs to be accessed by two companies. We have two NICs on the server, one goes to our local "shop floor" network (10.200.145.0/24) which ...
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27 views

What does interface state “configuring” mean?

My systemd-networkd-wait-online.service fails. When I take a look: % networkctl IDX LINK TYPE OPERATIONAL SETUP 1 lo loopback carrier ...
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2answers
35 views

have a intenal dns and a external dns with the same domain.

is it possble to have an internal dns with all the internal ip like 192.168.0.0/24 for a domain and an external for the same domain. i want to have bind resolve all the internal address and if a ...
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0answers
29 views

Connecting 2 Offices to the same network [closed]

So we have 2 offices that are on the same floor but each is connected to a different network. Now, we want to connect them to the same network. For example, we want to connect Office B to the Office A ...
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1answer
30 views

Custom subnet for Digital Ocean private networks

Hopefully this is a quick fix that someone can help me out with. I have spun up some droplets & enabled private networking. They communicate with each other with no issues. The current subnet let'...
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0answers
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Netfilter: force IPv6 client to use another source address

I have a network with two IPv6 subnets: one is a native connectivity and one is a Hurricane Electric 6in4 tunnel. When clients initiate a connection towards the Internet, they usually choose a source ...
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0answers
29 views

Openvpn routing through Socks

I have server which installed Openvpn as server. Server IP 192.168.1.1 Its work normally, i can connect the from vpn client without any problem. -Then i install socks5 server on same machine i bind ...
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0answers
20 views

Connection between containers fails with java.net.NoRouteToHostException: No route to host (Host unreachable)

I am using the docker-compose.yml from here. However, the connection bewteen the 2 containers (sonarqube to postgres) fails with the following error: sonarqube_1 | java.net.NoRouteToHostException: ...
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0answers
40 views

Virtualbox, host - Windows 10, guest - Ubuntu, guest does not connect to internet nor gets an ip [closed]

I tried lots of settings to get vulnhub challenge Node: 1 working. But it seems that no matter what I try, the machine does not get an ip assigned. Be it bridged or host only ,when I run arp -a or ...
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0answers
19 views

Socket binding and sending on different addresses

I have already posted this question here (https://stackoverflow.com/questions/52653506/udp-socket-binding-and-sending-behavior-on-windows-1709) but also want to ask similar here. I've been debugging ...
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1answer
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How do https stacks handle failed links when there are multiple A records?

I have setup DNS entries so that a certain FQDN has four A records, with four IPv4 addresses of four networks boxes converging thru a router to a single https server. That does load balancing across ...
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0answers
20 views

SFP to RJ45 on Debian 8 Not Detected

I have problems with an sfp to RJ45 module. I have a server with sfp ports and a switch with RJ45 port. So I plug a Gigabit ethernet cable from the switch to the SFP to RJ45 module on the server. ...
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0answers
21 views

docker compose containers not given access to host

I have a question very similar to this one: Iptables rule-set so that a docker container can access a service on a host IP where my containers are not being allowed to access the host. The problem ...
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0answers
38 views

some servers won't reply to SYN if client is on VPN

We have some ubuntu 18.04 servers (both physical and VMs) that will ignore pings and TCP connections coming from clients connected to our intranet via VPN. It is only fresh installs of 18.04 that are ...
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0answers
18 views

Correct firewall config for “Messages for Web” android sms website?

Having trouble with Google's hot new messages.android.com service. Most of the time it works great, but at my corporate office when my phone and laptop are on the corporate network it doesn't connect ...
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1answer
75 views

Powershell: Configure a static IP on an unplugged NIC

I'm trying to find a way to configure a permanent static IP on Windows 10 IOT devices with their Nic unplugged. I have a script that needs to be run on the devices before they're in place and part of ...
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1answer
31 views

iptables block outgoing on port, allow selected IP's [duplicate]

Debian 7 iptables v1.4.14 (there are no rules) Need to block all outgoing connections on ports 25,587,465 and allow only on specific IP's. What I've tried: iptables -A OUTPUT -p tcp --match ...