Red Hat Bugzilla – Bug 156417
bring back legacy ptys
Last modified: 2007-11-30 17:11:05 EST
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Description of problem:
As near as I can tell (without being a kernel expert), you have to
rebuild the kernel from source to enable "legacy ptys". I have as least
one old no longer supported commercial app I'd like to run, but it needs
these old style ptys to work (so I keep an ancient redhat 7.1 box
around for it).
Redhat also ships at least one app I know of (kermit) where the pty feature
simply doesn't work without the legacy pty support (gotcha! :-).
If there is a security issue involved, it would be nice for this to be
available as a boot option rather than having to rebuild the kernel.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. One example that demonstrates this is to make an attempt to use
any feature of kermit (such as the ssh command) that trys to run
a subprocess in a pty.
Actual Results: kermit doesn't print an error, but also doesn't work. If you run it
under strace you can see it trying various forms of pty access.
Expected Results: It should work :-). (Actually, kermit does have ifdefs to make it use
the openpty library, so I have built a working version of kermit from
the source downloaded from columbia's kermit project - perhaps redhat
should adjust their kermit build as well if legacy ptys aren't gonna
eventually, these will even go away upstream. Yes, there are security concerns,
among other problems, and reenabling them isn't an option.
reassigning to kermit maintainer.
Created attachment 113908 [details]
Patch I used to build working kermit
I don't recommend this as an official fix to build a working kermit (I just
hacked on the redhat9 target rather than making a new target for
enterprise/fedora), but it did build a kermit which seems to work on
my FC3 system.
Add -DHAVE_PTMX to KFLAGS in ckermit.spec.
It helps me.
If it works, it works, but I will just mention that using the openpty
library seems like it would be less likely to break if ptys change
again, since (one would hope) the openpty lib would remain compatible
even if the details of ptys didn't.