Questions tagged [packet]

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iPerf3 UDP TX/RX bytes mismatch but no loss

I am not able to interpret the following iPerf3 results. Client: iperf3 -c SERVER -u -R -b 350M Connecting to host SERVER, port 5201 Reverse mode, remote host SERVER is sending [ 5] local CLIENT ...
kingofworms's user avatar
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Packet capturing using arp poisoning and IP forwarding

I made a script in Golang that allows me to perform ARP poisoning attack and with that I enabled IP forwarding to forward the packets to my router. When I use pcap.OpenLive I can only see the packets ...
has van's user avatar
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Bad mask /30 for address 10.1.1.3 || Cisco P.T

So basically I'm having this issue while trying to configure the serial of 3 routers (router0, router1, router2) on Cisco Packet Tracer I was able to configure both serials for router0 following this ...
Roy Najar's user avatar
1 vote
0 answers
212 views

How can I maximize UDP Packet Size?

I am a gamer. I play UDP-based games. I want to increase the packet size. I know the UDP packet size is 1024 but i want to increase this packet size even more. I want to increase the performance I get ...
Tuna Enis's user avatar
1 vote
1 answer
104 views

How to find the linux user that sent the packet [duplicate]

Our server is compromised and we would like to know which accounts sent the malicious queries from our server. I used tcpdump to get this : our.host.net.48194 > box5596.bluehost.com.http: Flags [P....
SmootQ's user avatar
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163 views

How to identify source, destination ip using STUN and DTLS protocols?

enter image description here Given image i'm not able to identify which is source and destination ip address ( client or server). From STUN protocol 1st packet it's user request so i thought 131.202....
David Roonie's user avatar
-1 votes
1 answer
241 views

What is signature in a packet payload?

What is a signature in a packet payload? Why are they even necessary ? Also traffic classifiers use signature to detect the type of protocol of packet like there are regular expressions for http ...
David Roonie's user avatar
1 vote
0 answers
97 views

How to limit packets per unit time on a particular interface (for vms)

I am using kvm and virtuozzo virtualization on my servers and each having 10 vms. I have to restrict DDOS attack from my VMS (i.e prevent VM from doing DDOS attack), I search on net and found that I ...
Ganesh Gosavi's user avatar
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43 views

How to use iptables to link two vlans

I have two networks, one being the main, with a network card eth1 (found on an Ubuntu Server 18.04 configured to be a router) and internal IP address 192.168.5.1 (with is the gateway) and another ...
Twambo Kalumba's user avatar
1 vote
1 answer
789 views

Forwarded Packets are received by namespace's veth0 but not received by application

I use libtins (It uses Pcap) to capture link layer packets and forward to a network namespace where the actual application runs on. Client(Browser) -> Server -> Pcap -> Pcap Send -> br0 (...
sqlbie's user avatar
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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 ...
InvisibleWolf's user avatar
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1 answer
47 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
madan nikalje's user avatar
1 vote
0 answers
42 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 -...
hakansel05's user avatar
1 vote
1 answer
1k 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 ...
Prashant Lakhera's user avatar
1 vote
1 answer
126 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 ...
FitzChivalry's user avatar
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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%" ...
rjmendaxx's user avatar
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1 answer
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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/...
Caleb Bolton's user avatar
1 vote
1 answer
378 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 ...
RoflcopterV RoflcopterV's user avatar
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1 answer
344 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 ...
dayuloli's user avatar
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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 ...
John Levine's user avatar
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1 answer
230 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 ...
Martin Forde's user avatar
-5 votes
1 answer
60 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 ...
Kenenbek Arzymatov's user avatar
1 vote
2 answers
505 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 &...
Umar Hayat's user avatar
1 vote
1 answer
705 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 ...
Pacnet's user avatar
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1 vote
1 answer
3k 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,...
Arun Xavier's user avatar
0 votes
2 answers
2k 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 - ...
cold_coder's user avatar
0 votes
1 answer
78 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 ...
Joel Page's user avatar
  • 113
2 votes
1 answer
5k 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 ...
Dillon Knight's user avatar
1 vote
0 answers
728 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 ...
Duke Nukem's user avatar
1 vote
1 answer
2k 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 -...
rahram's user avatar
  • 113
-3 votes
1 answer
109 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 ...
user375197's user avatar
0 votes
1 answer
166 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.
krisk's user avatar
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0 votes
1 answer
383 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 ...
Yekoor's user avatar
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7 votes
1 answer
15k 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 ...
Andrew Bucklin's user avatar
0 votes
1 answer
1k 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 ...
Rjak's user avatar
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0 answers
2k 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 ...
Baz's user avatar
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-3 votes
1 answer
3k 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 ...
Adrian Nica's user avatar
1 vote
1 answer
3k 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 ...
GPointer's user avatar
1 vote
0 answers
78 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 ?
ner aredob's user avatar
0 votes
2 answers
1k 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 ...
Gizmo's user avatar
  • 289
0 votes
2 answers
359 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.
RebelUA's user avatar
  • 11
-2 votes
1 answer
106 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?
Jacksonkr's user avatar
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0 votes
1 answer
55 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 ...
Raiden616's user avatar
  • 119
-1 votes
4 answers
261 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 ...
Rooster's user avatar
  • 495
-1 votes
1 answer
4k 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. ...
E_Blue's user avatar
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0 votes
1 answer
2k 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....
Eddie Bui's user avatar
2 votes
2 answers
4k 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 ...
ballofpopculture's user avatar
2 votes
1 answer
7k 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. ...
Totem's user avatar
  • 145
2 votes
3 answers
453 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 ...
Totem's user avatar
  • 145
1 vote
1 answer
2k 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 ...
JohnRong's user avatar