Date: Sun, 22 Aug 1999 02:41:08 -0400 (EDT) From: Barrett Richardson <barrett@phoenix.aye.net> To: "Andy V. Oleynik" <andyo@prime.net.ua> Cc: freebsd-isp@FreeBSD.ORG Subject: Re: Problem with ICMP when aliasing enabled? Message-ID: <Pine.BSF.4.01.9908220213490.8107-100000@phoenix.aye.net> In-Reply-To: <37BE568F.4EA45BEE@prime.net.ua>
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On Sat, 21 Aug 1999, Andy V. Oleynik wrote: > I'll try to clarify situation. > Client use M$WinXXX to dialup into FBSD ppp server which > provides ppp with aliasing on server side. I didnt especially > disable aliasing on dialup modem pool coz I dicided that it > didnt matter in the dialup case. Generally aliasing is ajusted > in default section and serves the leased mppp link to the > base backbone (defaultroute). Thus aliasing propagated on > the dialup ppp links too. And dialup clients(real dynamic IPs) > say that they have usual tcp traffic but they cant to ping remote > hosts but the dialup ppp server. And I can ping clients only from > dialup ppp server only but not from another hosts. Though ECHO > requests goes through the dialup links w/o any replies. > Was I clear? > |backbone---------echo requests w/o replies ---------------> > | > |-------------|Client1 > |-------------------------------| ppp dialup server|---echo requests with > replies----------> > | mppp leased link with > |-------------|ClientN > | aliasing > dialup ppp with propagated aliasing > > Try this: On a host that can't ping one of the dial-up ppp clients delete the arp entries. Run tcpdump on the dial-up server and watch for arp activity. Then ping a ppp client from one of your hosts that has had trouble reaching the ppp clients. Look for an arp request with tcpdump and also the arp reply. Look for network address mismatches between the arp request and the arp reply (if there is a a reply). If the hosts and ppp dialup have the same network address, the dial-up server should answer arp requests for the dial up clients. If they are on different networks, the host doing the ping should arp for a router (possibly the default gateway) -- which may be something else to investigate (their default gateway may not know how to reach the dial up hosts -- can only guess without knowing your topology). Also, there is a recent thread in one of the lists concerning proxy-arp oddities that may be worth searching for. I didn't read any of the messages, just remember seeing it in the subject line. - Barrett To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isp" in the body of the message
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