Unix and Linux Stack Exchange
Unix and Linux Stack Exchange

Questions tagged [tcp-ip]

58 questions
44
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4 answers

Simple shell script to send socket message

For testing purposes I need to create a shell script that connects with a remote IP>Port and sends a simple text TCPIP Socket message.
Bachalo
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14
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4 answers

Can I have a single server listen on more than 65535 ports by attaching an IPv4 address

I have a number of servers to SSH into, and some of them, being behind different NATs, may require an SSH tunnel. Right now I'm using a single VPS for that purpose. When that number reaches 65535 - 1023 = 64512, and the VPS runs out of ports to…
ᴍᴇʜᴏᴠ
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10
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1 answer

How to investigate a random reset on TCP client port connected via loopback interface to a server

I have a test suite which initializes a server on the localhost and then runs thousands of stress tests which include starting and stopping clients connecting to this local server on same machine. I am trying to find the reason for a RST sent by…
carolinian
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1 answer

Comunicate with remote Serial over TCP/IP as /dev/ttyX device

I've one serial device on 192.168.x.x:yyyy (where "x" and "y" are real number) and it works correctly. But I want to communicate with this as /dev/ttyX device. I've tested socat command but not working correctly $ while true; do socat…
Domenico M.
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9
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3 answers

Disabling PHY auto-negotiation during Linux boot process on Xilinx

I'm trying to install Linux on an FPGA board. The linux flavour is petalinux for Xilinx FPGA chips. The current Xilinx SoC has a Cortex A9 processor and a programmable hardware logic i.e FPGA. I captured the boot message on the terminal: …
user2799508
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7
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3 answers

ICMP : Port unreachable error even if port is open

I am testing my Debian Server with some Nmap port Scanning. My Debian is a Virtual Machine running on a bridged connection. Classic port scanning using TCP SYN request works fine and detects port 80 as open (which is correct) : nmap -p 80…
hg8
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2 answers

What does net.ipv4.tcp_app_win do?

I can't figure out why the tcp_adv_win_scale and tcp_app_win variables coexist in Linux.  The information from tcp(7) says: For tcp_adv_win_scale: tcp_adv_win_scale (integer; default: 2; since Linux 2.4) Count buffering overhead as…
javag87
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5
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2 answers

Why does telnet on a non existent port not directly reject, but time out?

telnet 8.8.8.8 8888 displays Trying... I was expecting, that this directly is refused. Background: When we have a NGINX reverse proxy server, it would be great, that it detects directly when the backend is not there.
Alex
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5
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2 answers

How to map an IP address to localhost

So I have an IP Address 5x.2x.2xx.1xx I want to map to localhost. In my hosts file I have: cat /etc/hosts 127.0.1.1 test test 127.0.0.1 localhost # The following lines are desirable for IPv6 capable hosts ::1 ip6-localhost ip6-loopback fe00::0…
user1532587
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5
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1 answer

UDP or TCP hole punching to connect two peers (each one behind a router)

I'm trying to connect directly (without 3rd party server) my computer to a friend's computer. We are both behind a ISP router, and would like (as a challenge!) to connect without modifying the router configuration. As suggested here and here, we…
Basj
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How do I configure Docker containers to have unique IP addresses that are not the default ones?

How do I configure Docker containers to have unique IP addresses that are not the default ones? The Docker containers will run Apache or some web service. These Docker containers will share one host that has one physical NIC. These containers must…
Kiran
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4
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2 answers

TCP keep-alive parameters not being honoured

I have a server running on my Linux box, also on which the following commands were run: $ cat /proc/sys/net/ipv4/tcp_keepalive_time 7200 $ cat /proc/sys/net/ipv4/tcp_keepalive_intvl 75 $ cat /proc/sys/net/ipv4/tcp_keepalive_probes 9 My server…
Wad
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4
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1 answer

How do I set a static IP address for a disconnected interface?

I am setting up an Arch/Manjaro-based machine that only occasionally will be connected to network. I.e. most of the time its Ethernet card is disconnected. I run into this curious problem - when I try to use networking commands the interface is down…
r0berts
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3
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TCP Stack tuning,(TIME_WAIT) - python process ignores sysctl setting?

I'm playing around with tuning various tcp settings for high number of outgoing client connections. I've put following in my /etc/sysctl.conf on Ubuntu 16.04. net.ipv4.ip_local_port_range = 18000 65535 net.ipv4.tcp_tw_recycle =…
Josh
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How to emulate LAN adresses locally?

I have this situation: a piece of software got hardcoded IP address (let assume it is being 196.10.10.100:20000) to which it binds a socket and sends TCP and UDP traffic to 196.10.10.9:20000 (hardcoded too). Problem is that for system to work there…
Swift
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