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#! rnews 2753 bsd Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!simtel!daffy!uwvax!uwm.edu!math.ohio-state.edu!sol.ctr.columbia.edu!startide.ctr.columbia.edu!wpaul From: wpaul@ctr.columbia.edu (Bill Paul) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: How to set up routing tables? Date: 21 Aug 1995 18:20:03 GMT Organization: Columbia University Center for Telecommunications Research Lines: 52 Message-ID: <41aiok$fnk@sol.ctr.columbia.edu> References: <ARNULF.95Aug17095614@arnulf.dialup.fu-berlin.de> <411n6s$e62@bonnie.tcd-dresden.de> <415a6d$eui@sol.ctr.columbia.edu> <419qij$r1h@bonnie.tcd-dresden.de> NNTP-Posting-Host: startide.ctr.columbia.edu X-Newsreader: TIN [version 1.2 PL2] Daring to challenge the will of the almighty Leviam00se, J Wunsch (j@bonnie.heep.sax.de) had the courage to say: : Bill Paul <wpaul@ctr.columbia.edu> wrote: [munch] : > : ># echo "set ipforwarding = 1" | gdb -k -w /vmunix /dev/mem : Won't work in FreeBSD though. (I think you'll get a ``Readonly file : system'' or so.) It does too work in FreeBSD (2.0.5 and up, anyway): skynet# sysctl -a |& grep forward net.inet.ip.forwarding = 0 skynet# echo "set ipforwarding = 1" | gdb -k -w /vmunix /dev/mem GDB is free software and you are welcome to distribute copies of it under certain conditions; type "show copying" to see the conditions. There is absolutely no warranty for GDB; type "show warranty" for details. GDB 4.13 (i386-unknown-freebsd), Copyright 1994 Free Software Foundation, Inc...(no debugging symbols found)... IdlePTD 192000 current pcb at 262000 #0 0xf010bb03 in mi_switch () (kgdb) (kgdb) skynet# skynet# sysctl -a |& grep forward net.inet.ip.forwarding = 1 (I wouldn't have posted it if I hadn't already tried it myself. :) If you omit the -w flag, _then_ you'll get an error from kvm_write() about not being able to change the variable value. : I rather like the sysctl version. It's less error-prone and allows : the kernel some sort of control (e.g. you can have read/only : variables). Aw, c'mon: blowing up the system by accidentally splattering junk all over kernel memory with the debugger is half the fun of running UNIX. :) Granted sysctl is nice, but gdb has its advantages too. -Bill -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~T~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -Bill Paul (212) 854-6020 | System Manager Work: wpaul@ctr.columbia.edu | Center for Telecommunications Research Home: wpaul@skynet.ctr.columbia.edu | Columbia University, New York City ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The Møøse Illuminati: ignore it and be confused, or join it and be confusing! ~~~~~~ "Welcome to All Things BSDish! If it's not BSDish, it's crap!" ~~~~~~~