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106 lines
3.3 KiB
Markdown
106 lines
3.3 KiB
Markdown
---
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layout: post
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title: bindsnoop
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date: 2022-10-10 16:18
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category: bpftools
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author: yunwei37
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tags: [bpftools, syscall, kprobe, perf-event]
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summary: This tool traces the kernel function performing socket binding and print socket options set before the system call.
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---
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## origin
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origin from:
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https://github.com/iovisor/bcc/blob/master/libbpf-tools/bindsnoop.bpf.c
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## Compile and Run
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Compile:
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```shell
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docker run -it -v `pwd`/:/src/ yunwei37/ebpm:latest
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```
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Run:
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```shell
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sudo ./ecli run examples/bpftools/bindsnoop/package.json
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```
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## details in bcc
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Demonstrations of bindsnoop, the Linux eBPF/bcc version.
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This tool traces the kernel function performing socket binding and
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print socket options set before the system call invocation that might
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```console
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impact bind behavior and bound interface:
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SOL_IP IP_FREEBIND F....
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SOL_IP IP_TRANSPARENT .T...
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SOL_IP IP_BIND_ADDRESS_NO_PORT ..N..
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SOL_SOCKET SO_REUSEADDR ...R.
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SOL_SOCKET SO_REUSEPORT ....r
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```
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```console
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# ./bindsnoop.py
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Tracing binds ... Hit Ctrl-C to end
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PID COMM PROT ADDR PORT OPTS IF
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3941081 test_bind_op TCP 192.168.1.102 0 F.N.. 0
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3940194 dig TCP :: 62087 ..... 0
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3940219 dig UDP :: 48665 ..... 0
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3940893 Acceptor Thr TCP :: 35343 ...R. 0
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```
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The output shows four bind system calls:
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two "test_bind_op" instances, one with IP_FREEBIND and IP_BIND_ADDRESS_NO_PORT
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options, dig process called bind for TCP and UDP sockets,
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and Acceptor called bind for TCP with SO_REUSEADDR option set.
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The -t option prints a timestamp column
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```console
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# ./bindsnoop.py -t
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TIME(s) PID COMM PROT ADDR PORT OPTS IF
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0.000000 3956801 dig TCP :: 49611 ..... 0
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0.011045 3956822 dig UDP :: 56343 ..... 0
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2.310629 3956498 test_bind_op TCP 192.168.1.102 39609 F...r 0
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```
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The -U option prints a UID column:
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```console
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# ./bindsnoop.py -U
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Tracing binds ... Hit Ctrl-C to end
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UID PID COMM PROT ADDR PORT OPTS IF
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127072 3956498 test_bind_op TCP 192.168.1.102 44491 F...r 0
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127072 3960261 Acceptor Thr TCP :: 48869 ...R. 0
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0 3960729 Acceptor Thr TCP :: 44637 ...R. 0
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0 3959075 chef-client UDP :: 61722 ..... 0
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```
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The -u option filtering UID:
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```console
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# ./bindsnoop.py -Uu 0
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Tracing binds ... Hit Ctrl-C to end
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UID PID COMM PROT ADDR PORT OPTS IF
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0 3966330 Acceptor Thr TCP :: 39319 ...R. 0
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0 3968044 python3.7 TCP ::1 59371 ..... 0
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0 10224 fetch TCP 0.0.0.0 42091 ...R. 0
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```
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The --cgroupmap option filters based on a cgroup set.
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It is meant to be used with an externally created map.
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```console
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# ./bindsnoop.py --cgroupmap /sys/fs/bpf/test01
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```
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For more details, see docs/special_filtering.md
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In order to track heavy bind usage one can use --count option
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```console
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# ./bindsnoop.py --count
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Tracing binds ... Hit Ctrl-C to end
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LADDR LPORT BINDS
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0.0.0.0 6771 4
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0.0.0.0 4433 4
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127.0.0.1 33665 1
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``` |