Learn to spot where packets vanish on Linux using simple tools and clear commands. 21.12.2025 | reading time: 3 min Packet drops break connections and ruin performance; this short guide shows how to locate drops on a Linux host using commands that reveal kernel and driver counters so he can act fast. Run a quick counter check Do it now: run `ip -s link show dev eth0` to read RX and TX counters and dropped packets; example output might look like: ```bash 3: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000 link/ether aa:bb:cc:dd:ee:ff brd ff:ff:ff:ff:ff:ff RX: bytes packets errors dropped overrun mcast 1024 10 0 2 0 0 TX: bytes packets errors dropped carrier collsns 2048 20 0 1 0 0 ``` Here he sees two RX drops and one TX drop recorded by the kernel; those are the first clues to follow. Compare kernel and driver statistics Look deeper: run `ethtool -S eth0` to ask the driver for hardware counters and `tc -s qdisc show dev eth0` to inspect queuing drops; if the kernel shows drops but the driver does not, the issue is often at the qdisc or socket layer, while driver counters implicate NIC or firmware. Measure connection-level effects Use `ss -s` to check TCP retransmits and `tcpdump -n -i eth0` to capture offending traffic; he should reproduce the problem, watch retransmits climb or packets disappear in captures, and correlate with the counter timestamps to pinpoint where packets were lost. Helpful knobs to change When drops point to buffer exhaustion try increasing ring sizes with `ethtool -G`, adjust qdisc limits with `tc qdisc replace` or enable GRO/TSO offloads with `ethtool -K`; make one change, then re-run `ip -s link` and a capture to confirm improvement. Next tools and steps If counters still confuse him, check dmesg for driver warnings, inspect NIC firmware versions, verify switch port statistics, and test with a different cable or host to rule out physical faults; document findings and iterate. Keep learning Finding packets that vanish trains his diagnostic instincts; pursue structured study to master Linux networking, and consider certifications like CompTIA Linux+ or LPIC-1 for a career boost, with bitsandbytes.academy offering focused exam preparation. Join Bits & Bytes Academy First class LINUX exam preparation. network troubleshooting utilities infrastructure
