Questions tagged [tcp]
The Transmission Control Protocol (TCP) is a core protocol of the Internet protocol suite.
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Is there way to disable tcp timestamps in macOS?
I am using macOS Ventura 13.3. I know that in Windows and Linux I can enable/disable TCP timestamps via netsh and sysctl commands.
In Linux, it is the net.ipv4.tcp_timestamps parameter. macOS has the ...
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How to properly trigger path mtu discovery
I've activate the pmtu attribute in my machine.
sysctl net.inet.tcp.path_mtu_discovery
net.inet.tcp.path_mtu_discovery: 1
then I've used /usr/bin/nscurl to send messages to a remote gateway with mtu=...
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weird connection request on macos m1 nettop
I see a weird connection request on macos m1 for nettop. This happens on other programs as well. these ips are blocked, but I am wondering what is causing this.
This happens specifically on macos, ...
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Macbook Pro - How do we terminate ALL ESTABLISHED connections?
How do I terminate ALL the ESTABLISHED tcp connections in Terminal?
I can use the command below to get a list of active & established connections:
netstat -anvp tcp | awk 'NR<3 || /ESTABLISHED/‘...
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Detect which process is attempting TCP connections
On my MacBook Pro (Monterey), I was looking at packet captures over a period of a few hours and I noticed that something on my box is, every few minutes, pinging other computers on the local network ...
- 437
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Strange Ports opened on my Iphone?
I've run NMAP several times on my home network in my campaign of learning the basics of network security.
So far all my devices except my PC have been Iphones/Chromebooks so nothing has been found in ...
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What is the Bonjour service _acp-sync._tcp used for? And why is it accessing my Apple AirPort Base station using a long and obscure string?
Scanning for Bonjour devices on my network shows a long and obscure string associated with my AirPort Base station using this Bonjour protocol _acp-sync._tcp. What is this? What is it for?
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Reset TCP/IP Stack without Rebooting?
This is a bit of an unusual question but I have a Mac server that gets hit with a lot of DDoS attacks. Usually my data center's mitigation system catches them but sometimes they slip through. When ...
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What is `intu-ec-client` listening on TCP port 8021?
I'm wondering how I can either kill it or change the port it listens on.
Neither lsof -nP -i4TCP:8021 | grep LISTEN nor netstat -av | grep 8021 or launchctl list | awk 'NR>1 {print $3}' | xargs -I %...
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Blocking SYN-Flood Attacks?
I've got a Mac web server that's been getting hit pretty regularly with SYN half-open attacks. I've looked in to various ways to combat this. I've found a lot of general information, but not very much ...
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Why my mac can not access external traffic to other port except 80, 443, 22?
I can access all website with standard port(80 and 443) example: domain.com, but why I cant access example.com:3030? I cant connect to MySQL and PostgreSQL, via direct host/port to external IP, but I ...
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sysctl setting net.inet.tcp.keepidle removed in 10.15. Is there a replacement setting?
My work requires long-running connections to databases that required this sysctl setting in earlier OSX versions. Since it no longer exists, these connections appear to remain open, but they ...
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Can't connect to TCP/IP printer with undescore "_" in the IP
I have a wireless printer that's connected to our private LAN in our workplace. There is a weird configuration for the printer that it requires two printers to be added. For color - 192.168.51.xxx and ...
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Packet sniffer for MacOS Mojave and above
I'm looking for a packet sniffer app that runs on MacOS in a GUI (I know I can accomplish some functionality with native CLI utilities like tcpdump).
Previously I used Packet Peeper, however it doesn'...
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Have DHCP for Wi-Fi and static IP for Ethernet?
I'm trying to connect to a device over Ethernet and set a static IP for the Ethernet to talk to the device. When I do this, I can talk to the device but it kills connection to the Wi-Fi and I can't ...
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Why is IMRemoteURLConnectionAgent contacting a Charter IP address
I never use iMessage. I never use iCloud. And yet I happened to check my Mac's current network connections and I found this:
IMRemoteURLConn 33557 me 7u IPv4 ...
0t0 TCP 192.168.1.198:57996-&...
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Login to AppStore over cellular data, jump on public wifi, download/install app is "safe"?
Is it "safe" to install an App as such:
(1) using only a cellular data connection (wifi turned off) login to the App Store.
(2) enable wifi.
(3) connect to public wifi network.
(4) disable cellular ...
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How does WireShark work on OS X? What processes does it interact with?
I'm looking for deep/detailed research into how the MacOS TCP stack works. Namely, what are the files/Dynamic Libraries that offer this service?
What Libraries does WireShark interact with?
My goal ...
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How to force open TCP 443 on my machine?
I turned off the firewall. Then, using nmap in the terminal, I issued the statement
nmap 127.0.0.1
and got
Starting Nmap 7.12 ( https://nmap.org ) at 2016-08-15 11:00 PHT
Nmap scan report for ...
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How to inspect TCP/IP packets
How can I inspect IP packets send through currently open TCP connections?
I opened a nettop utility in Terminal, which I think lists IP packet, but doesn't tell anything about their content, namely ...
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Which process is using port 4000 (identified as remoteanything by nmap)?
I've run nmap -sS [computer ip] and see that i only have one service running:
PORT STATE SERVICE
4000/tcp open remoteanything
What service is this? Should i close it? I've googled and only ...
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How to increase value of tcbhashsize parameter in OS X
I am running OS X 10.11 - El Capitan. I am trying to tune my TCP setting for better network / Internet performance. Most of the settings I have been able to modify permanently through /etc/sysctl.conf ...
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How to Use Terminal for "Little Snitch" Functionality without Little Snitch
I'm a Terminal newb, and trying to wrap my head around manual "Little Snitch" functionality without using Little Snitch.
From the research I've been doing, I've landed on the fact that I need to ...
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How to put Wifi card in monitor mode?
When I run tcpdump, I do so after having connected to an access point.
Is there a way to run tcpdump without having connected already?
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How to enable echo service for tcp or udp on well-known port 7 on Mac OS X 10.8 or above?
I am learning TCP/IP protocol with a Mac, and need echo service (refer to [RFC 862], or Wiki) to test network. But it seems to OS X doesn't implement it or disable it.
I learned that launchd replaced ...
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OS X - List all active sockets
I'm looking for a simple command that will list ALL currently active and/or otherwise bound TCP & UDP sockets, corresponding port numbers and their respective states (i.e. ESTABLISHED, LISTEN, ...
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Find who is intercepting traffic on port 80
Every 7–10 days, all internet browsing on my Mac stops working. I can use Firefox, Safari, Chrome, but I'm able to surf only Google and few other sites.
So I tried to telnet a webserver on the local ...
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How can I limit bandwidth for a specific port/app in OS X 10.10 Yosemite?
I am running OS X 10.10 Yosemite, and I am looking for a way to limit upload bandwidth specifically on TCP port 8333, so I can run Bitcoin Core to contribute outgoing bandwidth without completely ...
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Limiting TCP connections
How can I limit TCP connections on Mac using Terminal?
I used iptables on Linux (eOS) to limit the connections of an application (Ace Stream Player) as follows:
$iptables -A OUTPUT -m limit --limit ...
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Network Ports Used To Print (Network LPD Printing)
I have been experimenting with an application that listens to network ports below 1024.
I discovered that when that application is running, an attempt to print to a network printer (set up to print ...
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How to increase max socket connections for Yosemite 10.10
I'm trying to test a network service app that allows for a large number of simultaneous socket connections.
I have adjusted /etc/sysctl.conf with the following:
kern.maxfiles=65536
kern....
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How to interface with iOS lockdownd
I used nmap to portscan my iPod Touch, and found a single port open, which was port 62078, labeled as "iphone-sync". I did some research, and found that the proccess behind it was a program called "...
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I have a service listening on a port, how do I open the port externally?
I have a service that is listening on a tcp port, and it is listed with this command:
>netstat -atp tcp | grep -i "listen"
tcp4 0 0 192.168.2.5.8070 *.* LISTEN ...
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TCP Congestion Control Algorithm of OSX10.7
How can I find out which algorithm OSX10.7 uses (NewReno, SACK, Tahoe...) and if possible, how can I change it?
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Open ports. Safe?
My friend is currently running the default firewall with "Block all incoming connection" (except the basic ones like 80). I just scanned his mac for open ports and I found the following:
Open TCP ...
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save IPv4 address for different WIFI
I have a macbook pro, that I use at work and in my house,
the problem is that i have to set up manually the TCP/IP IPv4 address for each place,
the address doesn't change once im on a location,
but I ...
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How do I further diagnose TCP connectivity (timeout) problems? (ICMP, DNS work fine)
I have two Macs behind a cable modem/WAP. One works fine. The other is able to ping servers but is unable to telnet to them. For instance pinging what.org works fine but I get operation timed out ...
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How can I ping a given host behind an Airport Extreme Base Station
I have an Airport Extreme Base Station (7.6.1) which has a public ip address on the WAN side. I have many hosts on the LAN side. I would like to configure the AEBS such that pings sent from the ...
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Postfix SMTP server slow to accept incoming connection
I have a snow-leopard os-x Server configuration running postfix with no local firewall on the X-Serve.
When a client attempts to connect to the SMTP port the connection takes about 15 seconds to ...
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How do I turn the echo service on in Snow Leopard?
I'd like to temporarily turn on the echo service (TCP and UDP port 7) on in Mac OS 10.6 (Snow Leopard). I guess this involves using the launchctl/launchd?
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How do you set the TCP congestion control algorithm on OS X?
I would like to set the TCP congestion control algorithm to Westwood+. Is this possible in OS X?
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