I realize that it is highly unlikely that Linux is at fault but I'm no
expert so I feel I should ask.

The symptoms are simple: passive-mode connections to ftp.netscape.com
fail. Here's an example:

--->ftp
ftp> debug
Debugging on (debug=1).
ftp> passive
Passive mode on.
ftp> open ftp.netscape.com
Connected to ftp.netscape.com.
220 ftp103 SGI 1.5: FTP server (Version wu-2.4.2-academ[BETA-17](20) Sat Jan 23 
23:20:31 PST 1999) ready.
---> USER anonymous
331 Guest login ok, send your complete e-mail address as password.
---> PASS XXXX
230-Welcome to the Netscape Communications Corporation FTP server.
230-
230-If you have any odd problems, try logging in with a minus sign (-)
230-as the first character of your password.  This will turn off a feature
230-that may be confusing your ftp client program.
230-
230-Please send any questions, comments, or problem reports about
230-this server to [EMAIL PROTECTED]
230-
230-***********  October 13, 1995  **********
230-Private ftp is now only on ftp1.netscape.com.  Anonymous is supported on
230-ftp 2 through 8.  If you are accessing a named account please use ftp1.
230-
230 Guest login ok, access restrictions apply.
---> SYST
215 UNIX Type: L8
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> ls
ftp: setsockopt (ignored): Permission denied
---> PASV
 
It dies here. The same thing happens if I telnet to the server.
Active-mode connections work.

More digging reveals that the server actually does send the PASV
response but 2.2.13 and 2.2.14pre* kernels ignore the packets. If you
turn off tcp timestamps then it works. Attached is a tcpdump of the
above transaction. A raw packet dump is also available.

I'm wondering what goes wrong and where.

Thanks.

10:03:25.315363 207.198.209.90.1044 > 207.200.79.194.21: S 2392222199:2392222199(0) 
win 32120 <mss 1460,sackOK,timestamp 19386 0,nop,wscale 0> (DF)
10:03:25.555363 207.200.79.194.21 > 207.198.209.90.1044: S 1223495111:1223495111(0) 
ack 2392222200 win 47784 <mss 1460,nop,wscale 0,nop,nop,timestamp 15965064 19386> (DF)
10:03:25.555363 207.198.209.90.1044 > 207.200.79.194.21: . ack 1 win 32120 
<nop,nop,timestamp 19410 15965064> (DF)
10:03:28.835363 207.200.79.194.21 > 207.198.209.90.1044: P 1:108(107) ack 1 win 47784 
<nop,nop,timestamp 15965070 19386> (DF) [tos 0x10]
10:03:28.835363 207.198.209.90.1044 > 207.200.79.194.21: . ack 108 win 32013 
<nop,nop,timestamp 19738 15965070> (DF) [tos 0x10]
10:03:28.855363 207.198.209.90.1044 > 207.200.79.194.21: P 1:17(16) ack 108 win 32120 
<nop,nop,timestamp 19740 15965070> (DF) [tos 0x10]
10:03:29.115363 207.200.79.194.21 > 207.198.209.90.1044: . ack 17 win 47768 
<nop,nop,timestamp 15965071 19740> (DF) [tos 0x10]
10:03:29.115363 207.200.79.194.21 > 207.198.209.90.1044: P 108:176(68) ack 17 win 
47784 <nop,nop,timestamp 15965071 19740> (DF) [tos 0x10]
10:03:29.115363 207.198.209.90.1044 > 207.200.79.194.21: P 17:47(30) ack 176 win 32120 
<nop,nop,timestamp 19766 15965071> (DF) [tos 0x10]
10:03:29.375363 207.200.79.194.21 > 207.198.209.90.1044: P 176:244(68) ack 47 win 
47784 <nop,nop,timestamp 15965071 19766> (DF) [tos 0x10]
10:03:29.395363 207.198.209.90.1044 > 207.200.79.194.21: . ack 244 win 32120 
<nop,nop,timestamp 19794 15965071> (DF) [tos 0x10]
10:03:29.735363 207.200.79.194.21 > 207.198.209.90.1044: P 244:825(581) ack 47 win 
47784 <nop,nop,timestamp 15965072 19766> (DF) [tos 0x10]
10:03:29.735363 207.198.209.90.1044 > 207.200.79.194.21: P 47:53(6) ack 825 win 32120 
<nop,nop,timestamp 19828 15965072> (DF) [tos 0x10]
10:03:29.965363 207.200.79.194.21 > 207.198.209.90.1044: P 825:844(19) ack 53 win 
47784 <nop,nop,timestamp 15965072 19828> (DF) [tos 0x10]
10:03:29.985363 207.198.209.90.1044 > 207.200.79.194.21: . ack 844 win 32120 
<nop,nop,timestamp 19853 15965072> (DF) [tos 0x10]
10:03:31.985363 207.198.209.90.1044 > 207.200.79.194.21: P 53:59(6) ack 844 win 32120 
<nop,nop,timestamp 20053 15965072> (DF) [tos 0x10]
10:03:32.215363 207.200.79.194.21 > 207.198.209.90.1044: . ack 59 win 47778 
<nop,nop,timestamp 15965077 20053> (DF) [tos 0x10]
10:03:32.215363 207.200.79.194.21 > 207.198.209.90.1044: P 844:894(50) ack 59 win 
47784 <nop,nop,timestamp 15965077 20053> (DF) [tos 0x10]
10:03:32.655363 207.200.79.194.21 > 207.198.209.90.1044: P 844:894(50) ack 59 win 
47784 <nop,nop,timestamp 15965077 20053> (DF) [tos 0x10]
10:03:36.945363 207.200.79.194.21 > 207.198.209.90.1044: P 844:894(50) ack 59 win 
47784 <nop,nop,timestamp 15965085 20053> (DF) [tos 0x10]
10:03:45.525363 207.200.79.194.21 > 207.198.209.90.1044: P 844:894(50) ack 59 win 
47784 <nop,nop,timestamp 15965101 20053> (DF) [tos 0x10]
10:03:46.825363 207.198.209.90.1044 > 207.200.79.194.21: F 59:59(0) ack 844 win 32120 
<nop,nop,timestamp 21537 15965077> (DF) [tos 0x10]
10:03:47.065363 207.200.79.194.21 > 207.198.209.90.1044: . ack 60 win 47784 
<nop,nop,timestamp 15965104 21537> (DF) [tos 0x10]
10:03:47.065363 207.198.209.90.1044 > 207.200.79.194.21: R 2392222259:2392222259(0) 
win 0 [tos 0x10]
10:03:47.065363 207.200.79.194.21 > 207.198.209.90.1044: FP 894:931(37) ack 60 win 
47784 <nop,nop,timestamp 15965104 21537> (DF) [tos 0x10]
10:03:47.065363 207.198.209.90.1044 > 207.200.79.194.21: R 2392222259:2392222259(0) 
win 0 [tos 0x10]

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