nanog mailing list archives
Re: IPSEC and PAT
From: "Tony Rall" <trall () almaden ibm com>
Date: Thu, 13 Sep 2001 20:23:47 -0700
On Thursday, 2001/09/13 at 21:43 AST, "Steven M. Bellovin" <smb () research att com> wrote:
I repeat -- it doesn't do PAT. Some "routers" -- they're really no such thing, of course; they're NAT boxes and/or bridges -- allow one host behind them to speak IPsec. If a host emits a packet using ESP, it's tagged as *the* IPsec user; return IPsec packets are routed to that host. (Some of these boxes may use manual configuration instead or in addition.) You can't have two IPsec hosts, because there's no way to know which should receive incoming packets -- there's no relationship between inbound and outbound SPIs.
Actually you can have multiple IPSEC sessions hidden behind a NAT box with a single public IP address - we've found several vendors' "routers" that can work in this environment. I believe the key is that each tunnel must be to distinct remote IP addresses. All the NAT box has available to separate the traffic for the different tunnels (which use IP protocol 50) is the address of the other end of the tunnel, but that is all it needs. Of course, many users would like to have multiple tunnels to the same partner. I don't know how that is possible with current IPSEC technology. Tony Rall
Current thread:
- IPSEC and PAT Vandy Hamidi (Sep 13)
- <Possible follow-ups>
- Re: IPSEC and PAT Steven M. Bellovin (Sep 13)
- Re: IPSEC and PAT Adam Herscher (Sep 13)
- RE: IPSEC and PAT Vandy Hamidi (Sep 13)
- Re: IPSEC and PAT Steven M. Bellovin (Sep 13)
- RE: IPSEC and PAT Tim Irwin (Sep 13)
- RE: IPSEC and PAT Vandy Hamidi (Sep 13)
- Re: IPSEC and PAT Tony Rall (Sep 13)
- Re: IPSEC and PAT Bora Akyol (Sep 13)
- Re: IPSEC and PAT Chris Grout (Sep 13)
- Re: IPSEC and PAT Adam Herscher (Sep 13)
- Re: IPSEC and PAT Bora Akyol (Sep 13)
- Re: IPSEC and PAT Steven M. Bellovin (Sep 13)