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25 views

Need to setup an intermediary to accept, alter and resend a UDP packet

Currently ApplicationA on ServerA sends a UDP packet to ApplicationZ on ServerZ several times throughout the day based on several triggers. The problem is that some of the data in that packet is sent ...
1
vote
1answer
24 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 ...
0
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0answers
6 views

How to route packets from a service (media service) based on the UID of the app that is using media service using IPTABLES

I am redirecting application packets through different PDN's based on their UID's (Process ID's) using IPtables. So my App1 is using PDN1 for its data transmission. and App2 is using PDN2 for its ...
1
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0answers
38 views

Cisco Packet Tracer Unable To Get OSPF to work [closed]

I'm pretty new to Cisco Packet Tracer as I'm currently in a computer networking course. I ran to an issue in which I am unable to resolve. I have four routers set up, R2, B1-R2, B2-R2, B3-R2. The ...
0
votes
3answers
43 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
41 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 ...
0
votes
1answer
55 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
100 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 ...
7
votes
1answer
183 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?
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0answers
67 views

Remove information revealed in packet inspection

I did a security scan of my server and got the following message: This test gives some information about the remote HTTP protocol - the version used, whether HTTP Keep-Alive and HTTP pipelining are ...
0
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0answers
113 views

Windows 7 DHCP Inform/Discover packet HLen=0

After introducing a Windows 7 machine onto my network, my DHCP server began to complain about receiving DHCP packets with an invalid mac length. It did not take very long to figure out that once ...
0
votes
1answer
28 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
85 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. ...
2
votes
3answers
2k 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
68 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 ...
2
votes
0answers
402 views

10GbE be2net low pktgen performance

I am testing the network performance of two workstations, each having 2.4GHz Xeon quad core processors and NC550SFP PCIe Dual Port 10GbE Server Adapters, linked back to back. I've checked the ...
0
votes
1answer
159 views

Dropping Packets Randomly

I have a SuperMicro Server based on the X9DR3-LN4F+ motherboard from SuperMicro. Original intentions for the system were quite different from what it has ended up serving, but that happens. It is ...
0
votes
1answer
192 views

What does a packet capture in pfsense do?

I have some issues with a third party to establish a VPN connection. To debug it, I made a packet capture on the device that represents our synchronous DSL line. The solution I'm using is an old ...
0
votes
1answer
80 views

Getting packet rate with tcpdump or iptables

I need to get the rate at which certain packets (i.e. LDAP) arrive on a interface in a linux environment. I was thinking of using tcpdump to filter the wanted packets and subsequently monitor the ...
0
votes
2answers
91 views

Caculating packet offset

In Wireshark, if I want to write a filter which accepts only ICMP destination unreachable ( type 3 ) messages, the filter is icmp[0] == 3 . How do I count the packet offset of 0 in this instance ? ...
1
vote
4answers
674 views

Smaller network packets vs bigger packets - confused

Some are saying that bigger packets are better to send then smaller. But in this app: http://media.pearsoncmg.com/aw/aw_kurose_network_2/applets/message/messagesegmentation.html The lower the packet ...
1
vote
2answers
191 views

Tracking actual packet path on a LAN

Is it possible to track the path a packet takes on a switched network. When I run a traceroute I get only the router and the destination. I know for a fact, however, that the packet must pass through ...
-1
votes
2answers
109 views

What happens when an unexpected packet arrives at a computer? [closed]

I have been wondering this for a few days. I basically understand how networks and packets work. But what happens when an unexpected packet arrives? Like, when I didn't send a request for a website's ...
1
vote
1answer
758 views

VMWare-ESXi server dropping packets, shaky connection

I have a few virtual servers running on a VMWare-ESXi server. One of those is a mailserver running Windows server 2003, Has been running quite well for a while now. About 4 days ago, the mailserver ...
1
vote
2answers
3k views

Intel 82579LM Gbit Ethernet Controller - magic packet (WOL) right after ping is not working

I am experiencing a very annoying and mysterious behavior when sending magic packets (for Wake On LAN) shortly after pinging an Intel 82579LM GigaBit Ethernet Controller (the onboard ethernet ...
0
votes
1answer
834 views

SMTP port open - but not open

As some of you might know, I am setting up an exchange server. Now I ran into another problem: I cannot connect to the SMTP service from outside the server! The ports are opened in the gateway ...
2
votes
1answer
2k views

iptables drop packet by hex string match

I got this packet captured with tcpdump but I'm not sure how to use the --hex-string param to match the packet. Can someone show me how to do it? 11:18:26.614537 IP (tos 0x0, ttl 17, id 19245, offset ...
2
votes
1answer
427 views

Check what the average packet size is in a network (what firewall/router should I get)

Is there any way to do this? We are looking into buying a Fortigate 100D but are unsure if it will hold up to our requirements. http://www.fortinet.com/products/fortigate/100D.html While the ...
0
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0answers
109 views

How to pervent vtp updates coming from vmware to go towards switch?

To get the background of this question please follow this link http://security.stackexchange.com/questions/14803/using-nessus-an-alien-packet-from-switch-shut-down-my-ethernet-card-completely I have ...
1
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0answers
643 views

Calculating the round trip time for ping packets

I am currently practicing for my network & communications course and have managed to confuse myself slightly on a question about packet round trip time. I have made a start but am now a bit stuck! ...
0
votes
1answer
258 views

How to block specific UDP packet outgoing from machine using iptables

I want to block specific UDP packet OUTGOING from my machine using iptables. Packet has a string in "hex in RAW"(?) i want to check packet by it. Like: If UDP packet hex RAW match "test_text" - block ...
0
votes
3answers
363 views

TCP firewall allows connection to external server but blocks response packets?

Consider this basic network setup: Client -> Router -> "Internet" -> Router -> Server Problem: the client can open a connection to the server and send data ("request"), but the server data packets ...
0
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1answer
96 views

Tools to inspect an ethernet packet travels through host's interfaces?

I am debugging a local ethernet connection on a Linux machine. I want to inspect the ethernet packets as they travel. in and out current machines' interfaces. I do not have a GUI on the machine. Is ...
-1
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1answer
195 views

Checking HTTP response for website using Wireshark

Is there a specific way to know if the file that we download through a web server (e.g.: Java) can be verified through Wireshark? I want to check if the file is working perfectly from internal and ...
5
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2answers
2k views

Configuring Frame Relay using a Switch Simulation - Packet Tracer

I have the following set up in Packet Tracer: I am trying to configure frame-relay between the RTR-EDGE router, the RTR_ENG router and the RTR_SAL router using a frame-relay switch simulation (the ...
1
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4answers
1k views

iptables : How to calculate how many bytes there're in a packet?

I'm working on a firewall and I would like to know how to calculate how many bytes there're in a packet or at least have an idea what the averages are. When I googled it, 1500 bytes was mentioned a ...
0
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1answer
165 views

iptables: is it possible to spoof NEW packets and make them look like ESTABLISHED packets?

See title for the question. This question relates to a previous question wherein I asked the difference between NEW,ESTABLISHED and RELATED , see it here iptables: difference between NEW, ESTABLISHED ...
9
votes
1answer
5k views

iptables: difference between NEW, ESTABLISHED and RELATED packets

Part of a firewall on a server : iptables -A INPUT -p tcp --dport 22 -m state NEW --state -m recent --set iptables -A INPUT -p tcp --dport 22 -m state --state NEW -m recent --update --seconds 100 ...
4
votes
1answer
531 views

Packet loss during TCP handshake

I have to implement a pseudo TCP handshake that leads into a file transfer. I have no problem doing the file transfer: simple send-acknowledge. What I can't wrap my head around is how to do the three ...
0
votes
1answer
95 views

size of packet icmp with netstat TX

I am confused with the size of packet icmp. I just did a simple initial netstat, where for eth0 : TX-OK = 485 after 1 ping message is send, again I see in netstat TX-OK = 488 So, I just want to know ...
0
votes
1answer
213 views

What is Reverse Gossip Transfer Protocol?

Playing with wireshark, I see a bunch of packets that say something like rgtp > https [ACK] Seq=???? Ack=?????? Win=????? Len=0 What is a Reverse Gossip Ttransfer Protocol? What is it used for, ...
2
votes
1answer
2k views

Linux bridge (brctl) is dropping packets

I have been researching this problem for a few days and have not found an answer yet. Your help will be really appreciated! I have a few VMs (Virtual Machines) running on a physical server. The ...
4
votes
2answers
5k views

Can 3G networks be packet sniffed / analyzed?

Just wondering if 3G networks can be sniffed like public wifi networks, via wireshark for example (I'm almost sure this is not possible due to encryption, but I just want to make sure?)
0
votes
2answers
228 views

Linux not sending ICMP with iptables `--reject-with`

Using iptables I am trying to reject packets (I want to return an ICMP message). iptables -A FORWARD [...] -j REJECT --reject-with icmp-port-unreach The packets are dropped but using tcpdump I can ...
0
votes
1answer
3k views

Good packet generator tool for IPv6.. Does hping3 support IPv6?

Does anyone of you know any good packet generator tool for IPv6. I am very familiar with hping3, but don't know if it supports IPv6. I am looking for something which can send, tcp, udp, icmp, and ...
2
votes
1answer
207 views

TCP sequence number and ACK number

Is the TCP sequence number just the ACK number + bytes received? Is it different when doing the 3-way handshake?
0
votes
1answer
51 views

Sharing connections on a circuit-switched network possible?

Is it possible to somehow share a circuit-switched connection? For example, could multiple computers be connected to a router which is connected to a circuit-switched network?
1
vote
2answers
117 views

What does “all packets that fall through to the default rule should be dropped” mean?

Does “all packets that fall through to the default rule should be dropped” mean that my iptables rule should drop everything at the start, like this? # Set the default policy to drop $IPT --policy ...
2
votes
1answer
186 views

Confusion about TCP packet analysis terms

I'm analyzing our network and have some confusion about the terms: this is the 2-packet output from source to destination. from these i have to get some features as describe, pls make me clear... ...
3
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3answers
13k views

How do you diagnose packet loss?

I realise this is very subjective and dependent on a number of variables, but I'm wondering what steps most folks go through when they need to diagnose packet loss on a given system?