Questions tagged as ['tcpip']

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"
Score: 0
v.doro2 avatar
APIPA ARP requests are send all over the network
cn flag

We have ~200 hosts running windows 10 and ~40 ip cameras all working with ip addresses from almost all of them sending arp requests to We have also virtual machines running on VMWare equipment and some of them are also sending those requests. print screen from wireshark

Ip cameras are known to have some weird network behavior, but regular PC's all together requesting apipa - ...

Score: -1
ragnar avatar
Transport layer port and firewall
in flag

When a communication is initiate the OS chooses randomly a port number greater than 1023. As long as it does not conflict with other ports in use on the system at that moment. I wonder how the firewall knows about this port? Or a firewall rule should always allow any port from the inside LAN?


Score: 0
hans2020dieter avatar
Routing Issue: Cannot reach target server from local network
my flag

1. my setup:

I've got an optical fibre ZTE router from my ISP for internet and telephone.

My old analog phone is connected directly to the router using the dedicated phone port on my router.

(For illustration I draw a network diagram down below.)

2. what I want:

I want to use SIP directly to make calls from my local network, instead of my old analog phone.

For example I want to install the softpho ...

Score: 1
TCP handshake not completing intermittently to specific Cloudflare node
cn flag

I have setup a webpage with Cloudflare that works nearly all of the time, except occasionally the TCP handshake fails with the SYN+ACK not making it to Cloudflare. On a packet capture from another machine on the network with the server, I can see the SYN arrive, the SYN+ACK is sent, but no ACK arrives, instead retried SYN packets come in and are replied to (see Wireshark log below). Users eventuall ...

Score: 0
Log TCP Client port on apache mod_proxy
cn flag

Using an Apache 2.4 Reverse Proxy (with mod_proxy) that connects to a backend HTTP service we have the following(simplified) series of TCP connections:

client ClientIP:random_port1 ---> <IP1:443 port> reverse_proxy <IP2:random_port2> ---> <IP3:8443 port> backend svc

We also get the following error in mod_proxy suggesting that we cannot make the second connection(IP2:random_port2 ...

Score: 0
Jonas Metzger avatar
Route all internet traffic through vsock channel
in flag

I can run arbitrary code on both a Linux server instance and a Linux VM inside the server. Both can only communicate to each other through vsock channels. Only the server instance has internet access.

I'd like to run one program on the server and one on the VM that connect to each other through vsock. The VM part intercepts any outgoing internet traffic and sends it to the server part via vsock w ...

Score: 0
Suketu Shah avatar
HA Proxy TCP Content Rejection
pk flag

I am looking for an option or a work around where I can accept or reject the TCP Content based on the the size of a file which is getting uploaded This settings is required on TCP IP layer only also we have tried options like req_len(not working), as well as src_kbytes_in(works fine only after first request is shared) if any one can help me on this I will be of greatful .

Score: 1
How to load balance Socket Connections?
cn flag

We have a large pool of devices that establishes socket connections with a server. Connections are TCP socket connections hitting a server IP: port pair from a destination IP port pair. In stand alone mode there is no problem in responding back to the devices.

However as the number of devices have scaled up, we are forced to introduce a load balancer which would then repool traffic to various rec ...

Score: 1
John avatar
Is it redundant to add an extra checksum or CRC in TCP packets to make it possible for the receiver verify whether the data is same with the sent one?
cn flag

As TCP contains a checksum and the TCP/IP stack will detect broken packets, is it redundant to add an extra checksum or CRC in TCP packets to make it possible for the receiver verify whether the data is same with the sent one?

Some thought about this question:

1.It's very common seen that there is a sha256 value to verify the consistency when downloading files from internet.

2.The checksum contai ...

Score: 1
John avatar
Is it useless to reply the received messages (on TCP) on application layer to tell the sender the messages have been successfully received?
cn flag

Any data loss is detected and automatically corrected, which is why TCP is also called a reliable protocol.

In other words,

the transport layer is responsible for error-free, end-to-end delivery of data from the source host to the destination host.

TCP is guaranteed to be a reliable transmission indeed. A question is raised, is it redundant (or useless, sorry for my poor English) to reply the receive ...