The Transmission Control Protocol (TCP) is a core protocol of the Internet protocol suite.

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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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241 views

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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54 views

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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194 views

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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32 views

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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112 views

pf port-forwarding on OS X Yosemite to avoid block

My ISP blocked a TCP port, let's say $ip1:$port1 So I setup $ip2:$port2 on my own VPS to get around it. How can I forward all traffic to $ip1:$port1 on OS X Yosemite as client to $ip2:$port2 using ...
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191 views

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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139 views

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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1k views

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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668 views

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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605 views

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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2answers
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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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3answers
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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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1answer
509 views

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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1answer
74 views

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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1answer
552 views

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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2k views

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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1answer
1k views

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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1answer
387 views

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?