Questions tagged [packet]
The packet tag has no usage guidance.
90
questions
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0answers
23 views
What's the expected behavior in TCP when hosts don't specify the MSS during handshake?
Let's suppose there are two hosts A and B and they are going to communicate over TCP. I am curious about the behavior of TCP related to MSS. Wikipedia says default value of MSS is 536. But, RFC-793 ...
0
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1answer
20 views
Is it possible to capture packets of router which i connected through wifi of my laptop
I want to capture all traffic of router I can only connect with wifi no physical access and I do have access to configuration page of router
0
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0answers
15 views
Does tcpdump guarantee packet integrity?
In normal use of tcpdump without any parameter, does it guarantee?
tcpdump -i eth0 -w file.pcap
In using tcpdump rotating by time with -G parameter, does it guarantee?
tcpdump -i eth0 -w file.pcap -...
1
vote
1answer
692 views
Is there is any tool/way to find out why packet is getting dropped due to an arp cache full?
My developer hypothesis is packet is getting dropped at arp layer. We increased the default value of neigh.default.gc_thresh3 1024 --> 2048 and now everything looks good. But I want to understand is ...
1
vote
1answer
85 views
Performing tasks and custom logic on network packets
I'm looking for a way to process packets in a Linux server in a particular fashion - I need to run some custom logic on every packet, then (possibly) take some actions on the packets and let the ...
0
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0answers
21 views
Use 2 dns for packet destinations in openvpn
I have a vps and openvpn is already installed on it. Clients' packet is important for me, if our packet destinations' IP is from Iran, using openvpn is not required but when the IPs are from out of ...
0
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0answers
34 views
HTML code trying to load PDF file from Site using ssl with self signed certificate
My employer has a web application that loads a pdf file onto the client browser by having a code that does the ff:
embed src="https://somepage.somesite.com/folderpath/somefile.pdf" width="100%" ...
0
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1answer
59 views
Can a router be connected to a both a subnet and a subnet inside that subnet?
Can a router be connected to both a subnet 1 and a subnet 1.1 which is a subnet inside of subnet 1?
For example, can a router be connected and sent packets to subnet 223.1.17.128/25 and 223.1.17.192/...
1
vote
1answer
81 views
IPTables or alternate solution to block the first attempt to connect then allow further attempts from same IP
I have a unique situation in which a DDOS attack for a certain game is sending realistic player connection packets that seem to perfectly mimic a real player's connection packet.
These typically ...
0
votes
1answer
52 views
In iptables, if a packet is ACCEPTed in one table, does it bypass the next table?
If a packet is ACCEPTed from, say, the INPUT chain of the mangle table, will it bypass the INPUT chain of the filter table and go straight to the local process? Or will the INPUT chain of the filter ...
2
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0answers
48 views
FreeBSD: redirect some UDP traffic from one port to another
I have some specialized DNS servers running on FreeBSD 11. A few people keep hammering on them and I would like to give them different answers. So I'd like to divert UDP traffic from those hosts from ...
0
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1answer
92 views
Force jumbo packet fragmentation
We are in a cluster environment. We have compute nodes with jumbo packets enabled and a MTU of 9000. We are running into some issues in tracebacks to an address outside of our lan, where jumbo packets ...
-5
votes
1answer
55 views
How packet is transmitted over the network? [closed]
I am writing discrete event-driven simulator to measure time between sending datasets over network.
If multiple processes sends n packets through network they (packets) will go one after one through ...
1
vote
2answers
443 views
Openvpn fails behind firewall but another VPN Works
Well I have spent last 48 hours trying to debug this but I'm about to give up now.
Mobile carrier in our country has a daily social bundle in which we can use ONLY whatsapp, facebook and snapchat &...
1
vote
1answer
373 views
How to send outgoing TCP packets on Windows through a remote Linux server?
Let's say I have a Windows computer and a Linux server. I'm looking for a way to route outgoing TCP packets on the Windows computer (all ports) through the Linux server.
The Linux server would have ...
1
vote
1answer
2k views
Understanding SoftEther VPN packet log
Help me to identify each part of a packet log from softether VPN.
for example, the below given is a packet log.
2017-06-07,23:40:20.888,SID-USER-[L2TP]-15,SID-SECURENAT-1,CA9DC6D826F0,00AC3A3F04D0,...
0
votes
2answers
1k views
How to mark packets depending on hostname?
We can mark packets on the basis of IP addresses in the following way -
iptables -A FORWARD -t mangle -s 123.2.3.4 -j MARK --set-mark 1
How to mark packets depending on the hostname? I tried this - ...
0
votes
1answer
61 views
High Traffic from Content Delivery Networks
I am having trouble on our school network recently. When browsing the internet users will often get an error from the browser saying "No Internet DNS_PROBE_FINISHED_NXDOMAIN" but when they refresh the ...
1
vote
1answer
4k views
Transportation Layer vs Network Layer [closed]
I am a networking student, and I am learning about the OSI system for networks. The concepts for this system are all pretty complicated, but the main issue that I'm having is the main differences ...
0
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0answers
462 views
Route HTTP packets into tun/tap interface
What I simply want is to redirect all HTTP packet from any interface to my tun/tap interface. A scapy script will listen on this interface and do some treatments to these packets.
First, I created a ...
1
vote
1answer
1k views
Accept ICMP packets (ping) with specific length - Iptable rules
I am going to filter Ping request to my server, and only accepts ping request with length 920.
ping -l 920 serrveraddress
I am using the following two command in iptables
iptables -A INPUT -p icmp -...
-3
votes
1answer
103 views
Linux firewall packet handling
When a client communicates with a the server via HTTP, for example, there are many packets going in both directions. It means from the client to the server and vice versa.
I would like to ask how ...
0
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1answer
105 views
Drop packet containing the selected string
How can I drop all packets on windows server that are containing a specific string?
The string is: TSource
Windows Firewall doesn't seem to have this kind of option.
0
votes
1answer
234 views
Force Windows to send packets as soon as they arrive the nic
I have a network application running on Windows Server 2008 R2, that must send small packets in a very short time interval, each microsecond matters. My problem is that windows accumulates the packets ...
5
votes
1answer
11k views
Outbound Packets Dropping / Timeouts - Only with Azure
I have an issue with packets dropping to a third party data center in Florida, USA. The issue only occurs on Azure Virtual Machines, no matter which data center the VM is in. I've done the same tests ...
0
votes
1answer
653 views
Extremely flaky connection to our EC2 instance through one connection, but not others
We have a robotic coffee barista deployed at the Dell campus in North Austin, with internet service through Time Warner Cable.
We have been fighting intermittent connection losses between 10PM - 1AM ...
0
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0answers
1k views
Getting chunks of high ms when pinging local / external IP addresses?
I am having difficulty identifying what a specific problem with one of your vlaned networks.
They have a voip phone which regularly cuts out during long phone calls.
I have done several ping tests ...
-3
votes
1answer
2k views
iptables rules for blocking specific packets [closed]
Im using the following iptables rule:
iptables -A INPUT -p tcp -m tcp --tcp-flags PSH,ACK PSH,ACK -m length --length 52 -m state --state ESTABLISHED -j DROP
It does it's job for blocking the ...
1
vote
1answer
2k views
iptables connlimit: exclude multiple IP addresses
I have currently this IPTABLES command:
iptables -A INPUT -s ! 192.168.0.2 -p tcp --syn -m connlimit [...] -j DROP
As far as I know, such rule limit some number of connections following various ...
1
vote
0answers
67 views
Split TCP packet - Data layer vs IPv4Layer
What is the different between split TCP packet in the Data layer compare to split the packet in IPv4Layer ?
0
votes
2answers
929 views
How to redirect a packet with iptables that match a certain pattern? (eg a QUERY command with UDP)
I have a certain packet that I want at all times to be redirected to a specific ip on my virtual network interface. As for now my iptables is setup like this:
(the commands, I use \ as for now to ...
0
votes
1answer
264 views
How many times does switch calculates FCS?
Does a switch calculate the Frame check sequence (FCS) before sending packets? Because packet shouldn't change, so FCS should also stay the same.
-2
votes
1answer
96 views
How many data packets does it take to log in to facebook? [closed]
I want to find out how many packets are sent when visiting a site on the web. What's a good program that would help me get this kind of data?
0
votes
1answer
33 views
See historical packet receipt statistics in Windows
I know this is a long shot, but it would be really useful to me right now.
Does anyone know of a Windows function or 3rd party tool that can show stats about the receipt of packets on a network ...
-1
votes
4answers
250 views
Is there anyway to tell what user will receive data from inbound packet?
In linux, considering this use case:
1. User initiates http request for webpage to remote server
2. Remote server answers request and sends packets
Is there any reference to the user who started ...
-1
votes
1answer
3k views
Set udp packet size limit
I have a CentOS server with a JAVA application that receive UDP data packets, it works all OK until the packet is bigger than 584 bytes, I read something about and seems to be a limit of UDP protocol.
...
0
votes
1answer
989 views
tcpdump show strange packet with incorrect src ip and dst ip
I have private LAN with > 100 servers, in which, I have 3 server:
x.x.x.37: run memcache on port 11211 (called s37 for short)
x.x.x.241: run an application server, which connect to memcache on
x.x.x....
2
votes
1answer
3k views
PF: Block all, but one subnet firewall rule?
I'm trying to do something that I thought would be relatively simple: Block all the traffic to a test server, other than my company's subnet.
I've tried things along these lines (111.111.0.0 is my ...
2
votes
1answer
6k views
TCP Sequence & Acknowledgment numbers
I have looked through other questions on here involving the relevant topics, but I am still not clear on this.
I have just been reading this explanation of TCP sequence & acknowledgment numbers.
...
2
votes
3answers
419 views
Is TCP header the same as TCP segment?
So, is a TCP header actually the same thing as a TCP segment? I was reading this page,
where it reads near the end that:
Even though it might seem they are, in most cases, when referring to
the ...
1
vote
1answer
349 views
Viewing the packet-size of an incoming IP
I have been looking for a sulution to this for a few hours. after no avail im asking for help here.
I need to watch my incoming packets by Size. in a format similar to:
IP SIZE
I have tried TCPDUMP ...
0
votes
3answers
3k views
How many packets will it take to send particular data?
If I know the maximum packet size is 1500 bytes say for Ethernet frame v2 then for example I want to transfer 1 KB over the Internet which is roughly 1024 bytes.
Will the packet be split into many ...
1
vote
1answer
142 views
Understanding ARP traces during OS load
Consider the following ARP packets captured while a unix machine was booting.
From the packets I understand that this machine whose MAC address is 00:22:22:22:22:22 is requesting information about ...
1
vote
2answers
251 views
Server sending packets every 5 minutes to 3 IPs
Been noticing in our firewall logs that three connections are being constantly established every 5 minutes from our web server and trying to send a packet to destination port 43 (whois port) cycling ...
1
vote
1answer
3k views
UDP maximum segment size
Environment:
I am writing a UDP client-server application. the path MTU between client and server is 1500 bytes (with only a wireless link between them, so this value is pretty much stable). My system ...
12
votes
1answer
20k views
Why is the “don't fragment” flag set in https and ssh protocols?
I've found a lot of information specifying that this is the case, however, I am really looking for the reason behind this. Why is it necessary? Is it necessary?
0
votes
1answer
47 views
forwarding of small and large packets: any difference?
When it comes to simple forwarding of packets (no errors being generated), are packets processed faster by routers when they are small as opposed to when they contain a large payload?
Or do routers ...
2
votes
0answers
368 views
Redhat 6.4 configured to log Martian packets but is not logging ll header
I am trying to investigate the source of martian packets I have been seeing on several servers connected to the same subnet. The logging of martian packets has been enabled in /etc/sysctl.conf.
...
7
votes
3answers
78k views
Excessive 'TCP Dup ACK' & 'TCP Fast Retransmission' causing issues on network. What's causing this?
I'm getting excessive TCP Dup ACK and TCP Fast Retransmission on our network when I transfer files over the MetroEthernet link. The two sites are connected by one sonicwall router, so the sites are ...
-1
votes
1answer
135 views
How do routers manage multiple data streams? [closed]
Routers manage data connections between the internet and computers or connections between computers on a LAN. It makes sense that when, for example, a computer requests music from Pandora, that ...
