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How to Find Source of Fake IP

ahmad82pkn
Level 3
Level 3

Hi, my router is hit by Fake traffic from IP 10.10.101.33

i can see it in my accounting packets.

10.10.101.33 doesnt exist in my LAN, its not a valid IP.

sh ip route 10.10.101.33

% Subnet not in table

Default route goes to Cisco ASA.

How can i find out MAC of this IP or any other way to find out where this IP belong in my LAN.

thats what i see in accounting.

and on firewall, all i see is SYN packets coming from inside and going to outside.

sh ip accounting | i 10.10.101.33

10.10.101.33     125.113.240.185                  1                  48

10.10.101.33     221.173.218.239                  1                  48

10.10.101.33     125.113.240.186                  1                  48

10.10.101.33     221.173.218.231                  1                  48

10.10.101.33     125.113.240.179                  1                  48

10.10.101.33     221.173.218.254                  1                  48

10.10.101.33     221.173.218.255                  2                  96

10.10.101.33     221.173.218.247                  1                  48

10.10.101.33     125.113.240.162                  2                  96

10.10.101.33     125.113.240.155                  1                  48

10.10.101.33     125.113.240.147                  1                  48

10.10.101.33     125.113.240.148                  1                  48

10.10.101.33     125.113.240.136                  2                  96

10.10.101.33     125.113.240.137                  4                 192

10.10.101.33     125.113.240.138                  1                  48

10.10.101.33     221.173.219.142                  2                  96

10.10.101.33     221.173.219.141                  2                  96

10.10.101.33     125.113.240.209                  2                  96

10.10.101.33     221.173.219.133                  1                  48

10.10.101.33     125.113.240.211                  2                  96

10.10.101.33     221.173.219.157                  2                  96

10.10.101.33     125.113.240.194                  1                  48

10.10.101.33     221.173.219.109                  1                  48

10.10.101.33     221.173.219.108                  2                  96

10.10.101.33     125.113.240.52                   1                  48

10.10.101.33     125.113.240.53                   1                  48

10.10.101.33     125.113.240.43                   1                  48

10.10.101.33     221.173.219.118                  1                  48

10.10.101.33     221.173.219.117                  2                  96

10.10.101.33     221.173.219.94                   2                  96

10.10.101.33     221.173.219.93                   2                  96

10.10.101.33     221.173.219.86                   1                  48

10.10.101.33     125.113.240.120                  1                  48

10.10.101.33     125.113.240.121                  1                  48

10.10.101.33     221.173.219.46                   2                  96

10.10.101.33     125.113.240.112                  1                  48

10.10.101.33     125.113.240.113                  1                  48

10.10.101.33     221.173.219.38                   2                  96

10.10.101.33     125.113.240.104                  2                  96

10.10.101.33     125.113.240.105                  1                  48

10.10.101.33     221.173.219.54                   2                  96

10.10.101.33     221.173.219.15                   2                  96

10.10.101.33     125.113.240.79                   1                  48

10.10.101.33     221.173.219.23                   1                  48

10.10.101.33     125.113.240.70                   1                  48

10.10.101.33     125.113.240.71                   1                  48

Logs on Cisco ASA

sh conn long | inc 10.10.101.33

TCP OUTSIDE:39.152.53.111/3306 (39.152.53.111/3306) INSIDE:10.10.101.33/8888 (10.10.101.33/8888), flags saA, idle 0s, uptime 0s, timeout 30s, bytes 0

TCP OUTSIDE:39.152.53.111/1433 (39.152.53.111/1433) INSIDE:10.10.101.33/8888 (10.10.101.33/8888), flags saA, idle 0s, uptime 0s, timeout 30s, bytes 0

TCP OUTSIDE:39.152.53.110/135 (39.152.53.110/135) INSIDE:10.10.101.33/8888 (10.10.101.33/8888), flags saA, idle 0s, uptime 0s, timeout 30s, bytes 0

TCP OUTSIDE:39.152.53.110/3306 (39.152.53.110/3306) INSIDE:10.10.101.33/8888 (10.10.101.33/8888), flags saA, idle 0s, uptime 0s, timeout 30s, bytes 0

TCP OUTSIDE:121.14.53.120/1433 (121.14.53.120/1433) INSIDE:10.10.101.33/8888 (10.10.101.33/8888), flags saA, idle 0s, uptime 0s, timeout 30s, bytes 0

TCP OUTSIDE:39.152.53.110/1433 (39.152.53.110/1433) INSIDE:10.10.101.33/8888 (10.10.101.33/8888), flags saA, idle 0s, uptime 0s, timeout 30s, bytes 0

TCP OUTSIDE:222.72.1.181/135 (222.72.1.181/135) INSIDE:10.10.101.33/8888 (10.10.101.33/8888), flags saA, idle 0s, uptime 0s, timeout 30s, bytes 0

TCP OUTSIDE:121.14.53.119/6673 (121.14.53.119/6673) INSIDE:10.10.101.33/8888 (10.10.101.33/8888), flags saA, idle 0s, uptime 0s, timeout 30s, bytes 0

TCP OUTSIDE:39.152.53.109/6667 (39.152.53.109/6667) INSIDE:10.10.101.33/8888 (10.10.101.33/8888), flags saA, idle 0s, uptime 0s, timeout 30s, bytes 0

2 Replies 2

Bilal Nawaz
VIP Alumni
VIP Alumni

Try having a look in the arp table.

Show arp | inc x.x.x.x

Sent from Cisco Technical Support iPhone App

Please rate useful posts & remember to mark any solved questions as answered. Thank you.

Andras Dosztal
Level 3
Level 3

Once you have the MAC address using what Bilal wrote, enter "show mac address-table xxxx.xxxx.xxxx" to find the interface it's connected to.

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