[root@bill ~]# cat pod_2 | radclient -r 1 -x 93.xx.xx.141:3799 coa skdjhfs
Sending CoA-Request of id 0 to 93.xx.xx.141 port 3799
        User-Name = "antipin_da"
        Mikrotik-Rate-Limit := "10240"
rad_recv: CoA-NAK packet from host 93.xx.xx.141 port 3799, id=0, length=42
rad_verify: Received CoA-NAK packet from client 93.xx.xx.141 port 3799 with invalid signature (err=2)!  (Shared secret is incorrect.)
radclient: no response from server for ID 0 socket 4

MK log:

Feb  9 08:20:17 93.xx.xx.141 radius,debug,packet received CoA-Request with id 0 from 217.xx.xx.94:44764
Feb  9 08:20:17 93.xx.xx.141 radius,debug,packet     Signature = 0x4418d7792fd59044a1ab55323631fae5
Feb  9 08:20:17 93.xx.xx.141 radius,debug,packet     User-Name = "antipin_da"
Feb  9 08:20:17 93.xx.xx.141 radius,debug,packet     MT-Rate-Limit = "10240"
Feb  9 08:20:17 93.xx.xx.141 radius,debug,packet sending CoA-NAK with id 0 to 217.xx.xx.94:44764
Feb  9 08:20:17 93.xx.xx.141 radius,debug,packet     Signature = 0x5efcd9033524f28b9679fcfee7260c62
Feb  9 08:20:17 93.xx.xx.141 radius,debug,packet     Error-Cause = 406
Feb  9 08:20:17 93.xx.xx.141 radius,debug,packet     NAS-Identifier = "hsgw"
Feb  9 08:20:17 93.xx.xx.141 radius,debug,packet     NAS-IP-Address = 93.xx.xx.141

[root@bill main]# pwd
/usr/local/src/radius/freeradius-1.1.8/src/main
[root@bill main]# cat /root/pod_2 | ./radclient -r 1 -x 93.xx.xx.141:3799 coa skdjhfs
Sending CoA-Request of id 173 to 93.xx.xx.141 port 3799
        User-Name = "antipin_da"
        Mikrotik-Rate-Limit = "10240"
rad_recv: CoA-NAK packet from host 93.xx.xx.141:3799, id=173, length=42
        Error-Cause = Unsupported-Extension
        NAS-Identifier = "hsgw"
        NAS-IP-Address = 93.xx.xx.141
[root@bill main]#