Michal Mertl wrote:
>
> I looked at the project page and noticed one thing I found code for.
>
> Task: Rework code in FreeBSD's ip_icmp.c such that ICMP responses for
> forwarding can be throttled also. Call badport_bandlim() before icmp_error()?
>
> Andres Oppermann wrote simple patch for it and posted it on net@ on January
> 2004.
>
> His (updated) patch attached.
>
> Sorry Andre for speaking on your behalf but I was afraid your work might get
> lost.
It already got lost from my brains memory. :( Maybe I would have found it
again when pruning my work trees. I'm going to commit it in the next few
days. Thanks for posting it and reminding me!
--
Andre
> --
> Michal Mertl
>
>
> --------------------------------------------------------------------------------
> Index: icmp_var.h
> ===================================================================
> RCS file: /home/fcvs/cvs/src/sys/netinet/icmp_var.h,v
> retrieving revision 1.24
> diff -u -r1.24 icmp_var.h
> --- icmp_var.h 16 Aug 2004 18:32:07 -0000 1.24
> +++ icmp_var.h 3 Dec 2004 14:31:08 -0000
> @@ -78,11 +78,12 @@
> extern int badport_bandlim(int);
> #define BANDLIM_UNLIMITED -1
> #define BANDLIM_ICMP_UNREACH 0
> -#define BANDLIM_ICMP_ECHO 1
> -#define BANDLIM_ICMP_TSTAMP 2
> -#define BANDLIM_RST_CLOSEDPORT 3 /* No connection, and no listeners */
> -#define BANDLIM_RST_OPENPORT 4 /* No connection, listener */
> -#define BANDLIM_MAX 4
> +#define BANDLIM_ICMP_UNREACH_HOST 1
> +#define BANDLIM_ICMP_ECHO 2
> +#define BANDLIM_ICMP_TSTAMP 3
> +#define BANDLIM_RST_CLOSEDPORT 4 /* No connection, and no listeners */
> +#define BANDLIM_RST_OPENPORT 5 /* No connection, listener */
> +#define BANDLIM_MAX 5
> #endif
>
> #endif
> Index: ip_icmp.c
> ===================================================================
> RCS file: /home/fcvs/cvs/src/sys/netinet/ip_icmp.c,v
> retrieving revision 1.97
> diff -u -r1.97 ip_icmp.c
> --- ip_icmp.c 15 Sep 2004 20:13:26 -0000 1.97
> +++ ip_icmp.c 3 Dec 2004 14:31:08 -0000
> @@ -172,6 +172,18 @@
> if (n->m_flags & (M_BCAST|M_MCAST))
> goto freeit;
> /*
> + * Limit sending of ICMP host unreachable messages.
> + * If we are acting as a router and someone is doing a sweep
> + * scan (eg. nmap and/or numerous windows worms) for destinations
> + * we are the gateway for but are not reachable (ie. a /24 on a
> + * interface and only a couple of hosts on the ethernet) we would
> + * generate a storm of ICMP host unreachable messages.
> + */
> + if (type == ICMP_UNREACH && code == ICMP_UNREACH_HOST) {
> + if (badport_bandlim(BANDLIM_ICMP_UNREACH_HOST) < 0)
> + goto freeit;
> + }
> + /*
> * First, formulate icmp message
> */
> m = m_gethdr(M_DONTWAIT, MT_HEADER);
> @@ -893,7 +905,8 @@
> struct timeval lasttime;
> int curpps;
> } rates[BANDLIM_MAX+1] = {
> - { "icmp unreach response" },
> + { "icmp unreach port response" },
> + { "icmp unreach host response" },
> { "icmp ping response" },
> { "icmp tstamp response" },
> { "closed port RST response" },
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