Is there any way by which we can find that the UDP port 500 is blocked at ISP side.
My IPSec VPN configured between two cisco router in production network is not coming up and experts are saying that the ISP has blocked the port 500 somewhere in between, however ISP denying and saying that they dont block any port.
You could scan the router's IP address on udp/500 using nmap.
If you have (or can insert) a switch between the router and ISP, you could span the port and capture traffic coming into your router from your initiating peer. capture the traffic on a PC running wireshark.
If your router platform supports it, you can also use Embedded Packet Capture (EPC). Reference.
How could I capture the traffic from initiating peer so that I can figure out that UDP port 500 is blocked or not, with the help of wireshark...
In my network ONT/Modem (having four ethernet port) is installed at both the end and from one of its port the router is connected at each side and IPSec VPN is configured between the router. to check the UDP port status, my question is, should i connect my laptop (running with wireshark) with one of the port of ONT and capture the traffice or is there any other way and how that traffice will tell me that port 500 is blocked or not?
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...