Ubuntu 18.04로 컴퓨터를 새로 설정하고 집 Wi-Fi에 연결했습니다. arp -a동일한 네트워크에 연결된 다른 장치를 검색하는 명령을 시도하면 매우 이상한 출력이 표시됩니다.
먼저 다음을 확인하여 연결이 잘 되었습니다 ifconfig.
john@home:~$ ifconfig
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1000 (Local Loopback)
RX packets 246054 bytes 21958490 (21.9 MB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 246054 bytes 21958490 (21.9 MB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
wlo1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.14 netmask 255.255.255.0 broadcast 192.168.1.255
inet6 fe80::e3f:e0a5:2438:a96a prefixlen 64 scopeid 0x20<link>
inet6 240d:1a:6a5:c900:1420:b3cc:994b:1b7b prefixlen 64 scopeid 0x0<global>
inet6 240d:1a:6a5:c900:74f4:f504:3a41:bc12 prefixlen 64 scopeid 0x0<global>
ether 04:33:c2:c4:02:a2 txqueuelen 1000 (Ethernet)
RX packets 2452125 bytes 3302288691 (3.3 GB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 964749 bytes 117659686 (117.6 MB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
IP 주소는 192.168.1.14입니다. 그런 다음 다음을 시도했습니다 arp -a.
john@home:~$ arp -a
? (192.168.1.19) at 92:c4:78:3c:46:16 [ether] on wlo1
_gateway (192.168.1.1) at e4:7e:66:1f:bf:4c [ether] on wlo1
? (192.168.1.5) at 26:36:46:f9:69:83 [ether] on wlo1
192.168.1.19내 아이패드의 IP 주소가 이고 휴대폰의 IP 주소가 다음과 같은지 확인할 수 있기 때문에 이는 의미가 있습니다.192.168.1.5
그러나 잠시 후 arp -a다시 실행해 보니 다음과 같은 결과가 나왔습니다.
john@home:~$ arp -a
? (192.168.1.206) at <incomplete> on wlo1
? (192.168.1.183) at <incomplete> on wlo1
? (192.168.1.107) at <incomplete> on wlo1
? (192.168.1.8) at <incomplete> on wlo1
? (192.168.1.18) at <incomplete> on wlo1
? (192.168.1.165) at <incomplete> on wlo1
? (192.168.1.186) at <incomplete> on wlo1
? (192.168.1.110) at <incomplete> on wlo1
? (192.168.1.77) at <incomplete> on wlo1
? (192.168.1.33) at <incomplete> on wlo1
? (192.168.1.178) at <incomplete> on wlo1
? (192.168.1.123) at <incomplete> on wlo1
? (192.168.1.112) at <incomplete> on wlo1
? (192.168.1.96) at <incomplete> on wlo1
? (192.168.1.117) at <incomplete> on wlo1
? (192.168.1.74) at <incomplete> on wlo1
? (192.168.1.95) at <incomplete> on wlo1
? (192.168.1.84) at <incomplete> on wlo1
? (192.168.1.41) at <incomplete> on wlo1
? (192.168.1.62) at <incomplete> on wlo1
? (192.168.1.51) at <incomplete> on wlo1
? (192.168.1.8) at <incomplete> on wlo1
? (192.168.1.29) at <incomplete> on wlo1
? (192.168.1.18) at <incomplete> on wlo1
? (192.168.1.231) at <incomplete> on wlo1
? (192.168.1.252) at <incomplete> on wlo1
? (192.168.1.241) at <incomplete> on wlo1
? (192.168.1.198) at <incomplete> on wlo1
? (192.168.1.219) at <incomplete> on wlo1
? (192.168.1.208) at <incomplete> on wlo1
? (192.168.1.165) at <incomplete> on wlo1
? (192.168.1.186) at <incomplete> on wlo1
? (192.168.1.143) at <incomplete> on wlo1
? (192.168.1.132) at <incomplete> on wlo1
? (192.168.1.153) at <incomplete> on wlo1
? (192.168.1.110) at <incomplete> on wlo1
? (192.168.1.99) at <incomplete> on wlo1
? (192.168.1.120) at <incomplete> on wlo1
? (192.168.1.77) at <incomplete> on wlo1
? (192.168.1.66) at <incomplete> on wlo1
? (192.168.1.87) at <incomplete> on wlo1
? (192.168.1.44) at <incomplete> on wlo1
? (192.168.1.33) at <incomplete> on wlo1
? (192.168.1.54) at <incomplete> on wlo1
? (192.168.1.11) at <incomplete> on wlo1
? (192.168.1.21) at <incomplete> on wlo1
? (192.168.1.234) at <incomplete> on wlo1
? (192.168.1.244) at <incomplete> on wlo1
? (192.168.1.201) at <incomplete> on wlo1
? (192.168.1.222) at <incomplete> on wlo1
? (192.168.1.211) at <incomplete> on wlo1
? (192.168.1.168) at <incomplete> on wlo1
? (192.168.1.189) at <incomplete> on wlo1
? (192.168.1.178) at <incomplete> on wlo1
? (192.168.1.135) at <incomplete> on wlo1
? (192.168.1.156) at <incomplete> on wlo1
? (192.168.1.145) at <incomplete> on wlo1
? (192.168.1.102) at <incomplete> on wlo1
? (192.168.1.123) at <incomplete> on wlo1
? (192.168.1.112) at <incomplete> on wlo1
? (192.168.1.69) at <incomplete> on wlo1
? (192.168.1.90) at <incomplete> on wlo1
? (192.168.1.47) at <incomplete> on wlo1
? (192.168.1.36) at <incomplete> on wlo1
? (192.168.1.57) at <incomplete> on wlo1
? (192.168.1.3) at <incomplete> on wlo1
? (192.168.1.24) at <incomplete> on wlo1
? (192.168.1.237) at <incomplete> on wlo1
? (192.168.1.226) at <incomplete> on wlo1
? (192.168.1.247) at <incomplete> on wlo1
? (192.168.1.204) at <incomplete> on wlo1
? (192.168.1.193) at <incomplete> on wlo1
? (192.168.1.214) at <incomplete> on wlo1
? (192.168.1.171) at <incomplete> on wlo1
? (192.168.1.160) at <incomplete> on wlo1
? (192.168.1.181) at <incomplete> on wlo1
? (192.168.1.138) at <incomplete> on wlo1
? (192.168.1.159) at <incomplete> on wlo1
? (192.168.1.148) at <incomplete> on wlo1
? (192.168.1.105) at <incomplete> on wlo1
? (192.168.1.126) at <incomplete> on wlo1
? (192.168.1.115) at <incomplete> on wlo1
? (192.168.1.72) at <incomplete> on wlo1
? (192.168.1.93) at <incomplete> on wlo1
? (192.168.1.82) at <incomplete> on wlo1
? (192.168.1.39) at <incomplete> on wlo1
? (192.168.1.60) at <incomplete> on wlo1
? (192.168.1.49) at <incomplete> on wlo1
? (192.168.1.6) at <incomplete> on wlo1
? (192.168.1.27) at <incomplete> on wlo1
? (192.168.1.16) at <incomplete> on wlo1
? (192.168.1.229) at <incomplete> on wlo1
? (192.168.1.250) at <incomplete> on wlo1
? (192.168.1.207) at <incomplete> on wlo1
? (192.168.1.196) at <incomplete> on wlo1
? (192.168.1.217) at <incomplete> on wlo1
? (192.168.1.174) at <incomplete> on wlo1
? (192.168.1.163) at <incomplete> on wlo1
? (192.168.1.184) at <incomplete> on wlo1
? (192.168.1.141) at <incomplete> on wlo1
? (192.168.1.130) at <incomplete> on wlo1
? (192.168.1.151) at <incomplete> on wlo1
? (192.168.1.108) at <incomplete> on wlo1
? (192.168.1.97) at <incomplete> on wlo1
? (192.168.1.118) at <incomplete> on wlo1
? (192.168.1.75) at <incomplete> on wlo1
? (192.168.1.64) at <incomplete> on wlo1
? (192.168.1.85) at <incomplete> on wlo1
? (192.168.1.42) at <incomplete> on wlo1
? (192.168.1.63) at <incomplete> on wlo1
? (192.168.1.52) at <incomplete> on wlo1
? (192.168.1.9) at <incomplete> on wlo1
? (192.168.1.30) at <incomplete> on wlo1
? (192.168.1.19) at <incomplete> on wlo1
? (192.168.1.232) at <incomplete> on wlo1
? (192.168.1.253) at <incomplete> on wlo1
? (192.168.1.242) at <incomplete> on wlo1
? (192.168.1.199) at <incomplete> on wlo1
? (192.168.1.220) at <incomplete> on wlo1
? (192.168.1.209) at <incomplete> on wlo1
? (192.168.1.166) at <incomplete> on wlo1
? (192.168.1.187) at <incomplete> on wlo1
? (192.168.1.176) at <incomplete> on wlo1
? (192.168.1.133) at <incomplete> on wlo1
? (192.168.1.154) at <incomplete> on wlo1
? (192.168.1.111) at <incomplete> on wlo1
? (192.168.1.100) at <incomplete> on wlo1
? (192.168.1.121) at <incomplete> on wlo1
? (192.168.1.78) at <incomplete> on wlo1
? (192.168.1.67) at <incomplete> on wlo1
? (192.168.1.88) at <incomplete> on wlo1
? (192.168.1.45) at <incomplete> on wlo1
? (192.168.1.34) at <incomplete> on wlo1
? (192.168.1.55) at <incomplete> on wlo1
? (192.168.1.12) at <incomplete> on wlo1
_gateway (192.168.1.1) at e4:7e:66:1f:bf:4c [ether] on wlo1
? (192.168.1.22) at <incomplete> on wlo1
? (192.168.1.235) at <incomplete> on wlo1
? (192.168.1.224) at <incomplete> on wlo1
? (192.168.1.245) at <incomplete> on wlo1
? (192.168.1.202) at <incomplete> on wlo1
? (192.168.1.223) at <incomplete> on wlo1
? (192.168.1.212) at <incomplete> on wlo1
? (192.168.1.169) at <incomplete> on wlo1
? (192.168.1.190) at <incomplete> on wlo1
? (192.168.1.179) at <incomplete> on wlo1
? (192.168.1.136) at <incomplete> on wlo1
? (192.168.1.157) at <incomplete> on wlo1
? (192.168.1.146) at <incomplete> on wlo1
? (192.168.1.103) at <incomplete> on wlo1
? (192.168.1.124) at <incomplete> on wlo1
? (192.168.1.113) at <incomplete> on wlo1
? (192.168.1.70) at <incomplete> on wlo1
? (192.168.1.91) at <incomplete> on wlo1
? (192.168.1.80) at <incomplete> on wlo1
? (192.168.1.37) at <incomplete> on wlo1
? (192.168.1.58) at <incomplete> on wlo1
? (192.168.1.15) at <incomplete> on wlo1
? (192.168.1.4) at <incomplete> on wlo1
? (192.168.1.25) at <incomplete> on wlo1
? (192.168.1.238) at <incomplete> on wlo1
? (192.168.1.227) at <incomplete> on wlo1
? (192.168.1.248) at <incomplete> on wlo1
? (192.168.1.205) at <incomplete> on wlo1
? (192.168.1.194) at <incomplete> on wlo1
? (192.168.1.215) at <incomplete> on wlo1
? (192.168.1.172) at <incomplete> on wlo1
? (192.168.1.161) at <incomplete> on wlo1
? (192.168.1.182) at <incomplete> on wlo1
? (192.168.1.139) at <incomplete> on wlo1
? (192.168.1.128) at <incomplete> on wlo1
? (192.168.1.149) at <incomplete> on wlo1
? (192.168.1.106) at <incomplete> on wlo1
? (192.168.1.127) at <incomplete> on wlo1
? (192.168.1.116) at <incomplete> on wlo1
? (192.168.1.73) at <incomplete> on wlo1
? (192.168.1.94) at <incomplete> on wlo1
? (192.168.1.83) at <incomplete> on wlo1
? (192.168.1.40) at <incomplete> on wlo1
? (192.168.1.61) at <incomplete> on wlo1
? (192.168.1.50) at <incomplete> on wlo1
? (192.168.1.7) at <incomplete> on wlo1
? (192.168.1.28) at <incomplete> on wlo1
? (192.168.1.17) at <incomplete> on wlo1
? (192.168.1.230) at <incomplete> on wlo1
? (192.168.1.251) at <incomplete> on wlo1
? (192.168.1.240) at <incomplete> on wlo1
? (192.168.1.197) at <incomplete> on wlo1
? (192.168.1.218) at <incomplete> on wlo1
? (192.168.1.175) at <incomplete> on wlo1
? (192.168.1.164) at <incomplete> on wlo1
? (192.168.1.185) at <incomplete> on wlo1
? (192.168.1.142) at <incomplete> on wlo1
? (192.168.1.131) at <incomplete> on wlo1
? (192.168.1.152) at <incomplete> on wlo1
? (192.168.1.109) at <incomplete> on wlo1
? (192.168.1.98) at <incomplete> on wlo1
? (192.168.1.119) at <incomplete> on wlo1
? (192.168.1.76) at <incomplete> on wlo1
? (192.168.1.65) at <incomplete> on wlo1
? (192.168.1.86) at <incomplete> on wlo1
? (192.168.1.43) at <incomplete> on wlo1
? (192.168.1.32) at <incomplete> on wlo1
? (192.168.1.53) at <incomplete> on wlo1
? (192.168.1.10) at <incomplete> on wlo1
? (192.168.1.31) at <incomplete> on wlo1
? (192.168.1.20) at <incomplete> on wlo1
? (192.168.1.233) at <incomplete> on wlo1
? (192.168.1.254) at <incomplete> on wlo1
? (192.168.1.243) at <incomplete> on wlo1
? (192.168.1.200) at <incomplete> on wlo1
? (192.168.1.221) at <incomplete> on wlo1
john@home:~$
이게 뭔가요? 방금 무슨 일이 일어났나요? 나는 arp -a동일한 네트워크에 있는 다른 장치를 검색하고 나열해야 한다고 생각했습니다. 이 결과는 무엇입니까?
답변1
나는
arp -a동일한 네트워크에 있는 다른 장치를 검색하고 나열해야 한다고 생각했습니다.
arp -a스캔하지 않습니다. 커널의 IPv4 네트워크 인접 캐시만 표시합니다. 출력의 모든 항목은 를 실행했기 때문이 아니라 이미 캐시에 있었기 때문에 존재하는 것입니다 arp.
이 결과는 무엇입니까?
불완전한 항목은 특정 IP 주소에 대한 네트워크 이웃의 MAC 주소를 검색하라는 요청이 전송되었지만 아직 응답이 수신되지 않았음을 의미합니다. 잠시 후에 유효한 응답이 있을 것이므로 항목이 완료되고 잠시 동안 캐시에 유지됩니다. 그렇지 않으면 유효한 응답이 없으며 불완전한 항목이 곧 캐시에서 제거됩니다.
방금 무슨 일이 일어났나요?
방금 OS의 무언가가 이러한 모든 IP 주소에 액세스하려고 시도했습니다. 예를 들어 실제 스캐너일 수도 있습니다 nmap 192.168.1.0/24.
완료되지 않은 불완전한 항목은 OS가 주기적으로 관련 IP 주소에 액세스하려고 시도하지 않는 한 결국 사라집니다. 새로운 접근 시도를 하면 해당 항목이 다시 나타납니다. 아니면 애초에 그것이 사라지는 것을 방지할 것입니다.
스캐너 등을 실행하는(또는 계속 실행하는) 사람이라면 걱정할 것이 없습니다. 게시된 출력은 arp -a정상입니다. arp -a지금은 몇 가지 항목만 인쇄 하더라도 다음과 같이 많은 항목이 인쇄됩니다.
nmap 192.168.1.0/24; arp -a
당신이 아니라면 조사해 볼 가치가 있습니다. 사용자가 모르는 사이에 OS에서 네트워크가 검색되었다는 사실은 OS가 손상되었음을 의미할 수도 있고 그렇지 않을 수도 있습니다.