I've got a Linux server running CentOS 7, and I've been facing an issue where the RX dropped packet count keeps increasing. I believe it may be caused by a faulty cable/connector in the network; however, I have no means of checking every connection to find the problem. Is there any way to see from which IP are the dropped packets coming?
Using nmap you can get a variety of information about your network including, and it can be incredibly useful for tracking packet loss. The
--packet-trace option can be useful for tracking all of the packets. While there are a great number of examples and guides for using nmap available online a simple way to start would be something like:
nmap -sP --packet-trace 192.168.1.0/24
Will scan the network for hosts and track the packets in the case of a timeout I got something like this on my local network
nsock_read(): Read request from IOD #1 [192.168.1.42:53] (timeout: -1ms) EID 66
The nmap call can be customized and scripted in a variety of ways to get more information about your network and try to weed out bad connections.
In addition to
nmap there is a graphical tool available called wireshark that can be used for a whole host of network profiling tasks including finding bad links/sources of dropped packets.
Depending on the switches and networking hardware used as well as your level of access you may be able to use the built-in management interface on the switches in your environment to look for physical ports with abnormally high rates of dropped packets. With certain brands of managable switches this sort of task could probably even be scripted/automated; the exact semantics of such an operation would depend on specific network hardware and configurations. In the right sort of environment using Simple Network Management Protocol(SNMP) may be a novel way to gather all of this information(dropped packets on physical switch ports, etc) from your network without too much work.
EDIT: In the above example EID is a DNS Resource Record(RR) and is an abbreviation for Endpoint IDentifier(EID).