Understanding netstat -r Ouptu

scottym · 06-10-2005, 12:44 PM

Hi,

What does it mean when their is a * in the gateway column as there is in the the following output:

$ netstat -r
Kernel IP routing table
Scott$ netstat -r
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
192.168.100.0 192.168.1.1 255.255.255.0 UG 0 0 0 eth1
192.168.3.0 192.168.1.1 255.255.255.0 UG 0 0 0 eth1
192.168.2.0 192.168.1.1 255.255.255.0 UG 0 0 0 eth1
192.168.1.0 * 255.255.255.0 U 0 0 0 eth1
192.168.10.0 * 255.255.255.0 U 0 0 0 eth0
169.254.0.0 * 255.255.0.0 U 0 0 0 eth1
default 192.168.10.1 0.0.0.0 UG 0 0 0 eth0

Also, I searched the manpage for netstat and couldnt find any explanation for the Flags column. What does U and UG mean?

(Sorry about the non-tabbed output, couldn't figure out how to get the vB tag to work.)

Thanks,

demian · 06-10-2005, 01:23 PM

Quote:

Originally posted by scottym
Hi,

What does it mean when their is a * in the gateway column as there is in the the following output:

It means you can reach the destination in one hop.

Quote:

Also, I searched the manpage for netstat and couldnt find any explanation for the Flags column. What does U and UG mean?

Search harder:

Quote:

man netstat said:

Code:

     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 packets (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