Configuring Access Control Lists 615
continued
•
flag [+fin | -fin] [+syn | -syn] [+rst | -rst] [+psh | -
psh] [+ack | -ack] [+urg | -urg] [established]—
Specifies that the IP/TCP/UDP ACL rule matches on the 
TCP flags. 
–
Ack
 – Acknowledgement bit 
–
Fin
 – Finished bit 
–
Psh
 – push bit 
–
Rst
 – reset bit 
–
Syn 
– Synchronize bit 
–
Urg
 – Urgent bit 
– When “+<tcpflagname>
” 
is specified, a match occurs 
if specified <tcpflagname> flag is set in the TCP 
header.
– When “-<tcpflagname>
” 
is
 
specified, a match occurs 
if specified <tcpflagname> flag is *NOT* set in the 
TCP header.
– When “established
” is 
specified, a match occurs if 
either the RST or ACK bits are set in the TCP header.
– This option is visible only if protocol is “tcp”.
•
[icmp-type
 icmp-type
 [icmp-code 
icmp-code
] |
 
icmp-
message 
icmp-message
] —
Specifies a match condition 
for ICMP packets.
– When icmp-type is specified, IP ACL rule matches on 
the specified ICMP message type, a number from 0 
to 255. 
– When icmp-code is specified, IP ACL rule matches on 
the specified ICMP message code, a number from 0 
to 255. 
– Specifying icmp-message implies both icmp-type and 
icmp-code are specified.
– ICMP message is decoded into corresponding ICMP 
type and ICMP code within that ICMP type. This 
option is visible only if the protocol is “icmp”.
– IPv4 ICMP message types: echo echo-reply host-
redirect mobile-redirect net-redirect net-unreachable 
redirect packet-too-big port-unreachable source-
quench router-solicitation router-advertisement time-
exceeded ttl-exceeded unreachable
Command Purpose