TCP and IP are two important protocols used in networking today. Due to their importance, the Internet Protocol Suite is also commonly known as "TCP/IP"

learn more… | top users | synonyms

1
vote
1answer
39 views

Tcp connection breaking, too fast for serial?

I've been having real difficulties getting a tcp connection to work with my web server. I think the issue might have something to do with the speed or ordering of the packets as the connection seems ...
1
vote
1answer
33 views

When connecting to localhost, does a full SYN, SYN-ACK, ACK handshake still occur?

This question is addressed, primarily for Linux. While I could find the answer myself, I'm hoping someone out there just knows the answer implicitly and can save me some time. If I'm connecting to a ...
1
vote
0answers
41 views

What should happen when receiving an ICMP Fragmentation Needed message?

In general, and in particular on a Solaris 10 machine ... See, we are having an issue in our network. I handle some reverse proxy instances on a Solaris 10 server that is behind a load balancer, and ...
1
vote
2answers
28 views

Can I add a static route to a VPN network if the default gateway IP is dynamic? (Windows 7)

Can I add a static route to a VPN network if the default gateway IP is dynamic? (Windows 7) This is easy to solve with a permanent route if the default gateway does not change as you can do this: ...
-1
votes
1answer
65 views

Why is wireshark capturing packets not destined to my host? [closed]

My IP was configured as 192.168.101.91, I don't understand why my host is receiving packets which have a destination address of 192.168.87.203(and many other IPs which I didn't capture) given that I ...
2
votes
0answers
93 views

Does a ping to 127.0.0.1 hit the network card? Which RFC / standard states that? [closed]

I recently did an exam where one of the questions stated that you can run ping 127.0.0.1 on a computer to verify if its network card is working. I have already read on multiple sources that this ...
2
votes
1answer
80 views

A local IP address (RFC 1918) on my network that is not … local

I've noticed an IP address today on my network (192.168.15.1) which when visited actually goes to a page that has a router webconfig page (Not my router) The puzzling thing is that i tried traceroute ...
1
vote
0answers
227 views

Event id 4227 tcp/ip warnings on Windows 7

We're deploying a new image out to the field, and we're seeing tcp/ip event id 4227 warnings periodically throughout the day (1-3 a day). The event message reads as follows: TCP/IP failed to ...
-1
votes
2answers
48 views

ASN number basics [closed]

I have the basic idea of ASN numbers. My question is how do routers know about them? It doesn't seem like it is signified by any bits in the datagram, so I assume it's done in the protocol. Once you ...
1
vote
1answer
39 views

high availabilty port forwarding in mswindows

I need port forwarding for a mswindows host, but I need something which can handle more than one target with fail over. There are no end of tools to do this on Linux/Unix (haproxy, balance, ...
0
votes
1answer
86 views

server is not responding on SYN packets

On the attached tcp dump, the first two SYN packets (#21800 and 21801) came to the server, however SYN ACK was sent for the second SYN. Is that correct behaviour? My understanding is that the client ...
0
votes
2answers
77 views

Why I cannot access EC2 instance public IP from inside of instance itself?

Here is an example, I have an Linux instance , say, private IP is 10.10.10.10, public IP is 54.54.54.54. Inside the instance, I could successfully ping it's private IP(10.10.10.10) and localhost. ...
1
vote
0answers
13 views

Can a firewall handle packets being sent to it by a network TAP?

We have the intention of examining incoming mails for security purposes. In order to do so we figured out the solution will include: Network TAP - To copy all SMTP traffic to the firewall Firewall - ...
1
vote
1answer
319 views

Can a port be in the listen state and be closed?

Servers running Debian7.7, Mongodb 1.2.0.6-1.1, Nmap6.0 - Thanks for your time. I've user who can't connect to mongodb from his Win7 desktop. He has mongodb installed on it and he's trying to connect ...
0
votes
1answer
120 views

TCP: out of memory - Nginx

I'm running a high traffic site on a nginx server. Last fews days I'm having problems with my VPS locking up (unable to SSH, and nginx seems to be down). When I look in the logs I can see the ...
4
votes
1answer
148 views

How does Windows 2008 specifically select ephemeral ports (does it test to avoid conflicts)?

I have a server application which uses permanently connected incoming ports within the range that W2k8 now uses in the IANA recommended range of ~49000-65000. (For legacy reasons it's extremely ...
0
votes
0answers
52 views

Outbound TTL of TCP/UDP connections on Server 2003 changes to 1

We have 4 2003 servers in an environment. Earlier this week, we had a problem where two of servers suddenly were unable to access the internet. Here's an overview of what I determined through ...
0
votes
0answers
51 views

sshd with port forwarding left connections to localhost without counterparty process

After temporary tunnel setup from X.X.X.X , from where I ran ssh -R 1089:localhost:1089 for several days, I have noticed this. I wonder what processes is 2494/sshd connected to, as no counterparty ...
7
votes
2answers
2k views

TCP Dump, cannot understand these 4 lines?

I need support understanding these 4 lines. looks like tcp dump but im actully not understanding what exactly is happening here. 13:13:22.407445 IP 192.168.246.128.54955 > 192.168.246.13.80: S ...
1
vote
0answers
37 views

An already acknowledged data sequence number is coming back as null byte repeatedly

There is a transaction processing server (TP-Server) to which my application (Client) connects to. We are seeing a strange packet sequence where in the TP-Server is sending a PUSH packet with a null ...
12
votes
3answers
2k views

How does the HTTP GET method work in relation to DNS protocol?

I am trying to understand application layer protocols in TCP/IP stack. I know that both HTTP and DNS protocol stay at the top layer (Application Layer). So, when a browser wants to access a resource, ...
0
votes
0answers
60 views

Early tear down of communication

I have an application which performs an LDAP search which works in one domain but not in the other, when analyzing the packets sent between the application server and the domain controller being ...
0
votes
1answer
218 views

External DNS takes a long time to resolve for AD computers

On our AD domain, end users desktops take a long time to resolve DNS from outside our company. Internally everything works fine. The desktops are pointing pointing to 192.168.2.4 and .6. Those are ...
0
votes
0answers
278 views

Connection Timeout Issues - Solaris 11 SPARC

We're currently running some performance tests using Solaris 11 (SPARC) on some large hardware. The tests, which consist of sending SOAP requests (50kb per request), are running well up until we get ...
2
votes
2answers
6k views

What is [PSH, ACK] doing during my connection to a global catalog server?

A linux server of mine is trying to establish a LDAPS connection to a global catalog server and the connection is getting dropped (presumably by the GC side). For the purpose of discussion, let's ...
0
votes
1answer
773 views

Port forward remote desktop without a gateway over 3G modem router [closed]

I'm trying to connect from a laptop, through a VPN, and a 3G modem/router, to a remote PC / computer. PC (192.168.1.33) | 3G Modem (192.168.1.22) | [3G internet, connecting to VPN] | ...
1
vote
2answers
105 views

Incoming tcp SYNs possibilities

This might be a general TCP question. Can I receive TCP SYN packet on an established connection OR a connection in TIME_WAIT state? Is is possible?
3
votes
2answers
695 views

When a server IP changes, do exising TCP (e.g. http/mysql) connections remain running

We have some PHP-FPM servers and when they need a database connection, they connect to an HAProxy server which selects them a database server to use and the connection opens. When we then want to ...
2
votes
1answer
73 views

How to compare 2 TCP/IP stacks or implementations? [closed]

I have to recycle an old machine into a networking node for managing TCP/IP connections and PPP protocols ( basically a DSL connection ); I'm not asking for something more than this, all the tasks ...
0
votes
0answers
351 views

Windows Server 2008 Enterprise - Print Server Role - TCP/IP Print Server Service Won't Start

I have a few Windows Server 2008 Enterprise edition Servers running Printer Server Roles. On these servers there are two system services: Print Spooler and TCP/IP Print Server (LPDSVC). The TCP/IP ...
2
votes
1answer
280 views

Host doesn't send ACK-SYN packets for transparent proxy

I am setting up a transparent proxy using haproxy, the setup works without the 'source 0.0.0.0 usesrc client' line. When I add that line in, the endpoint is called from the original client's ip ...
-6
votes
1answer
61 views

What is the incentive to operate a TCP/IP node? [closed]

I mean, why does anybody relay messages to other nodes? Why are these eleven good people below helping me send my bytes to their destination? traceroute to stackoverflow.com (198.252.206.140), ...
3
votes
2answers
2k views

Can you use WMI to determine if a connection gets its DNS servers from DHCP?

The DNS server search order for a network interface can be read from Win32_NetworkAdapterConfiguration like this in Powershell, or programmatically using .Net ManagementObjects: > $NICs = ...
1
vote
0answers
71 views

Printer lpd daemon refuses print job if a command's new-line sent separately — bug?

I'm encountering some printer LPD daemons which work fine if the new-line is sent in the same packet as the command, but break if the new-line is sent in a separate packet. Is that a bug in these ...
0
votes
1answer
120 views

TCP client and server work for X times but hang after that

I'm a software engineer, but I think my problem needs a network engineer... For the software side of things, have a look at my Stack Overflow question: ...
-2
votes
2answers
1k views

List of TCP & UDP ports known to be used by malware, etc [closed]

Where can I find a regularly updated, downloadable list of TCP & UDP ports that are known to be commonly used by malware, trojans, etc.? This is for import into an IT asset management system to ...
-1
votes
1answer
61 views

Firewall Connections fail to open under load

Problem : During High load , our applications are encountering errors : java.net.connection Time out. After some investigation , we found out that it was Firewall the root cause, but still don't know ...
0
votes
1answer
146 views

Could the IPG parameter in Robocopy cause TCP/IP packet problems if it is too high?

I need to throttle a robocopy transfer to limit bandwidth usage. It is already set to 1500 (/IPG:1500). I would like to increase this IPG to around 2000 (or more) in order to lower even more the ...
3
votes
2answers
347 views

once in a while windows / .net application ignores the tcp fin flag

i've run into a network problem which i cannot solve. on a few computers running windows 8.1 and communicating with linux http server tcp connections dangle on the windows side instead of being ...
3
votes
1answer
9k views

What else does “netsh int ip reset” do?

According to this KB article when you run the "netsh int ip reset" command, all it does is to reset the content of two registry keys: SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\ ...
1
vote
1answer
2k views

ping -a sometimes returns host name and sometimes returns FQDN. Why? Does this mean DNS is corrupt somehow?

I have a Windows machine called abcd for example and it uses DHCP to receive an IP address (172.28.45.5 for example) When I perform ping -a 172.28.45.5 sometimes I receive abcd as the hostname. ...
2
votes
1answer
5k views

Diagnosing packet loss / high latency in Ubuntu

We have a Linux box (Ubuntu 12.04) running Nginx (1.5.2), which acts as a reverse proxy/load balancer to some Tornado and Apache hosts. The upstream servers are physically and logically close (same ...
0
votes
1answer
410 views

Server with two default gateways won't listen on the second gateway

I am testing a redundant internet connection setup that works like this - I have a network segment, 192.168.80.X It has two gateways - 192.168.80.1 - a FW connected to a frame relay line ...
4
votes
2answers
10k views

ESXi network setup for isolated internal virtual machines

Using ESXi v5.1 and vSphere, my networking is setup like so: One standard Switch: vSwitch0 vSwitch0 has one uplink physical adapter (Internet connected) vSwitch0 VM Network has 3 virtual machines ...
0
votes
1answer
3k views

Where to find WINS IP address in registry?

I have been writting a powershell script to remotely dump the TCPIP information from the registry of machines in my Windows Domain. I was able to dump the default gateway, subnet mask, DHCP server ...
-1
votes
1answer
104 views

Need help routing Cisco network- IP routing [closed]

In the above network, can you help me configure routes so the computers on the left can see the computers on the right, and vice versa? I know the syntax of the command is ip route {network ...
0
votes
0answers
344 views

SSH attempt keeps failing, syn+ack does not reach machine

1 0.000000 10.0.0.1 10.1.1.0 TCP 66 49285 > ssh [SYN] Seq=0 Win=8192 Len=0 MSS=1260 WS=256 SACK_PERM=1 2 0.001160 10.1.1.0 10.0.0.1 TCP 66 ssh > 49285 [SYN, ACK] Seq=0 ...
1
vote
1answer
303 views

Do keepalives to socket connections exist?

Pre briefing: Although my question is broad on purpose, I am dealing with nginx connecting to php-fpm (fcgi), which is served via a local socket (/tmp/somesocket.socket). Nginx has a setting to ...
0
votes
1answer
419 views

is it possible to use ms loop back adapter to setup local vlan

Is it possible to use Microsoft Loop back adapter to set up Lan connection between two computer which is logically isolated from the main network? 1st computer: has a regular ip stack 192.168.1.x ...
1
vote
2answers
2k views

How to globally limit total number of TCP connections with iptables?

I'm having quite a difficult time figuring out how to REJECT both inbound and outbound connections from a machine with iptables once the total number of TCP connections hits a global maximum without ...