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Questions tagged [ip-fragmentation]

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TCP Retransmissions when packets exceed 1500+

I am currently trying to communicate using NMOS protocol over my network. This is a /30 network. The issue I am seeing is that when I send an http request from my computer to my device over the ...
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0answers
71 views

Forwarding Fragments with IPTables / FirewallD

I have a linux (openSuse Leap 15.0) computer that's connected to a cable modem using PPoE (hopefully not relevant to this. EDIT the ppp0 interface has an mtu of 1492 but the eth0 interface it is "...
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1answer
316 views

RDP connections failing under specific circumstances

Problem RDP connections from PCs or servers in both branch sites to the RDSH server in the main site are intermittently failing with the following error: A licensing error occurred while the client ...
0
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1answer
967 views

Reassembly fails at destination

Say I have Host1 & 2 connected to a router with different speeds. Host1 <--100 Mbps--> Router <--10 Mbps--> Host2 Host1 sends 10MB of UDP data using nc command to Host2, but the ...
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1answer
3k views

Where IP fragments are reassembled into one fragment? [closed]

Reading about IP fragments found controversy between various teaching materials. In book: "Fragments need to be reassembled before they reach the transport layer at the destination." "The ...
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1answer
10k views

Forcing IP fragmentation and reassembly for some traffic thru a VPN tunnel

Is there a way to force IP packet fragmentation before they go into tun0 and then force reassemble them on the other side of tun device? I have some IPSec traffic that I can not control, and it wants ...
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1answer
606 views

VPN problems: MTU and Don't-Fragment

I am setting up a VPN on Ubuntu 14.04LTS which uses IPSEC and performs NAT for clients. It is basically working - I can connect to it from a clinet (Android device) and browse (for example) www....
0
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1answer
774 views

Fragmented DNS Packet

The DNS response against my domain is 1228 bytes long and I need the packet to get fragmented in 3 packets. To achieve this I have set the MTU at name server (bind9 running on the machine) to be 500. ...
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0answers
2k views

Does netfilter reassemble IP fragments when packet is forwarded?

IP datagram should be reassemble in the termination of the path because the fragments may arrive from different paths. I think Netfilter need to reassemble a IP datagram to inspect the whole payload ...
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2answers
14k views

OpenVPN: How to mitigate path MTU issues on a per-client basis?

We have dozens of embedded devices installed at customers, all calling home to our OpenVPN service. That works fine in general, but a few of our customers have severe path MTU issues. Our influence on ...
0
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1answer
368 views

Can a source send two fragmented IP packets at the same time?

I'm developing an app that does NAT between a virtual TAP interface and a physical interface, and I'm not sure how much buffer should I allocate for IP fragmentation. According to Wikipedia the ...
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1answer
17k 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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1answer
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Why is iptables rejecting the second and subsequent fragments of an allowed packet?

I have two hosts which are attempting to set up an IPSec connection with each other. For this they have to communicate on UDP ports 500 and 4500, so I opened them in the firewalls on both ends (shown ...
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1answer
1k views

Does Windows XP automatically reassemble UDP fragments?

I've got a Windows application that receives and processes XML messages transmitted via UDP. The application collects the data using Windows "raw" sockets, so the entire layer 3 packet is visible. ...
4
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1answer
445 views

Matching last fragment of IP packets using tc or ipfilter

I am transmitting UDP packets of say 2900 bytes. Due to fragmentation, packet is divided in 2 IP fragments. My tc u32 filter (more fragments bit and IP/PORT combination) matches only first fragment ...
3
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1answer
93 views

IP segmentation occouring at irregular boundaries

I have an IP packet of header length of 20 Bytes and data length of 4096 Bytes. The maximum transfer unit of the network is only 1500 Bytes. As I understand fragmentation, the fragmented packet will ...
3
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2answers
188 views

seeing remote MTUs of 250 and 68. is this ever valid?

I'm seeing an ICMP storm from a mobile phone netblocks belonging to "TELEFONICA MOVILES". Periodically we will get upwards of 5 million in a few seconds, all something like this: 08:12:05.740781 IP (...
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3answers
1k views

Implementing IP fragmentation

I'm working on an application that does network traffic generation. The application has eth1 in promiscous mode. So it directly handles all incoming and outgoing traffic. One of the features I'm ...