Understanding routing table flags
#netstat -r
#route
The output is very handy and helps in troubleshooting your network problem. The flags if you can understand will help you much more. So here is the summary of the flags and their meaning.
Flag | Name | Meaning |
|
|
|
1 | RTF_PROTO1 | Protocol specific routing flag 1 |
2 | RTF_PROTO2 | Protocol specific routing flag 2 |
3 | RTF_PROTO3 | Protocol specific routing flag 3 |
B | RTF_BLACKHOLE | Just discard pkts (during updates) |
b | RTF_BROADCAST | The route represents a broadcast address |
C | RTF_CLONING | Generate new routes on use |
c | RTF_PRCLONING | Protocol-specified generate new routes on use |
D | RTF_DYNAMIC | Created dynamically (by redirect) |
G | RTF_GATEWAY | Destination requires forwarding by intermediary |
H | RTF_HOST | Host entry (net otherwise) |
L | RTF_LLINFO | Valid protocol to link address translation |
M | RTF_MODIFIED | Modified dynamically (by redirect) |
R | RTF_REJECT | Host or net unreachable |
S | RTF_STATIC | Manually added |
U | RTF_UP | Route usable |
W | RTF_WASCLONED | Route was generated as a result of cloning |
X | RTF_XRESOLVE | External daemon translates proto to link address |
I have not been able to find the O flag documented(capital alpha O )
ReplyDeletethe following flags are set for the route: UO
I also don't understand the C flag (Capital). What does it mean "generate new route on use" ? what actually happens?
Thanks!
Google:
ReplyDeleteRTF_CLONING is set when the route is added (either manually, or
automatically for interface routes) to indicate that a more specific
route (possibly a host route) needs to be generated on every unique
lookup.
Regarding the capital O I'll see if I can generate it somehow. Please wait when I have some free time.
What mean the Flag A?
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