问题
I have code written in C. I want to get using C code information that is stored in routing table. Is it possible?
回答1:
You can open a netlink socket and send route update messages. There is an article about how to do this.
回答2:
You can also run "strace route add ..." to see how the route command does it.
On my system, it uses ioctl with SIOCADDRT. A little searching turns up some sample code.
Oddly, the best documentation I have found is from IBM's AS400 man pages.
If you just want to read the routing table, you can open and read /proc/net/route. (Again, strace shows that this is how the route command does it.) The hex numbers are 32-bit IP addresses in machine-endian form. Try cat /proc/net/route.
回答3:
If you want to query the routing table only, try to read the file /proc/net/route. It works in my system.
来源：https://stackoverflow.com/questions/6358431/can-i-read-write-the-routing-table-in-c-without-using-system-command