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Why two network with NAToverload not communicate?

I have two private networks: 192.168.1.0 192.168.2.0 These networks communicate with each other via static routing, but when I set up the NAT overload, they don't communicate. Why? I examined the ...
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0answers
94 views

reducing bufferbloat in linux web server

I'm looking for all the buffers I can tune in linux as well as their order of operation. On the server, nearly all operations are run over the TCP protocol. I want to eliminate bufferbloat to improve ...
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0answers
132 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 ...
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1answer
123 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 ...
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vote
1answer
144 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 ...
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0answers
30 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 ?
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2answers
233 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 ...
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0answers
89 views

packet is not being forwarded from tap interface to bridge

I am running fedora 19 on a virtual machine and have two tap interfaces (A, B) created. I'd like to be able to send packet from A to B. I am trying to do this using a bridge, however with the bridge ...
0
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1answer
53 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.
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0answers
43 views

Bonding connection or other techniques to improve UDP delivery

I have several VOIP servers linked by heavily loaded connections, and the voice quality gets pretty spotty at times. I have setup QoS to ensure upstream bandwidth is allocated favorably for VOIP, ...
-2
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1answer
69 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
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1answer
24 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 ...
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4answers
234 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 ...
0
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1answer
517 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
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1answer
203 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 ...
1
vote
1answer
893 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 ...
0
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1answer
2k 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. ...
1
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3answers
185 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
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1answer
65 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 ...
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3answers
193 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
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1answer
86 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
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1answer
134 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
650 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
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1answer
3k 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
300 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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1answer
34 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
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0answers
197 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. ...
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3answers
22k 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 ...
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1answer
84 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
1answer
1k 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
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1answer
1k 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
539 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
216 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 ...
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2answers
178 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 ? ...
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4answers
3k 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 ...
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2answers
871 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
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2answers
166 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
2k 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 ...
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2answers
6k 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
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1answer
1k 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 ...
5
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1answer
4k 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
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1answer
892 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 ...
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0answers
1k 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
444 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
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3answers
773 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
116 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
votes
1answer
264 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
4k 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 ...
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4answers
2k 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
226 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 ...