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We enable end-users of domain A to communicate with their home proxy based on TLSonTLS:
User Agent A -> proxy domainA
Prerequisites
This example is based on
- Debian 4r0
- OpenSER version 1.2 with tls
User Agent A — TLS — > proxy domainA
Prerequisites
- Linux machine
- SER version 2.0rc or higher
- Server certificate and private key in PEM fomrat
- CA list - list of trusted authorities in PEM format
If you use binary package, see if it supports TLS. command ser -V should show something like
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ser -V
version: ser 2.0.0-rc1 (i386/linux)
flags: STATS: Off, USE_IPV6, USE_TCP, USE_TLS ......
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and tls module (tls.so) has to located in module directory (depends on distribution and package i.e. /usr/local/lib/ser/modules)
Otherwise you have to recompile SER from source. Download daily snaphot from iptel.org or from CVS.
Make everything
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make group_include="standard" include_modules="tls" all
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Install it (and make before)
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make group_include="standard" include_modules="tls" install
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You can adjust compiled modules by group_include, include_modules and exclude_modules parameters.
Print-modules parameter show set of modules that will compiled.
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make group_include="standard" include_modules="tls" print-modules
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Configuration
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# ----------- global configuration parameters ------------------------
debug=3 # debug level (cmd line: -dddddddddd)
#memdbg=10 # memory debug message level
#memlog=10 # memory statistics log level
log_facility=LOG_LOCAL0 # sets the facility used for logging (see syslog(3))
/* Uncomment these lines to enter debugging mode
fork=no
log_stderror=yes
*/
check_via=no # (cmd. line: -v)
dns=no # (cmd. line: -r)
rev_dns=no # (cmd. line: -R)
#port=5060
children=2
#user=ser
#group=ser
#disable_core=yes #disables core dumping
#open_fd_limit=1024 # sets the open file descriptors limit
#mhomed=yes # usefull for multihomed hosts, small performance penalty
#disable_tcp=yes
#tcp_accept_aliases=yes # accepts the tcp alias via option (see NEWS)
enable_tls=yes
alias=domainA
listen=tcp:1.2.3.4:5060
listen=udp:1.2.3.4:5060
listen=tls:1.2.3.4:50
#
# ------------------ module loading ----------------------------------
loadmodule "/usr/local/lib/ser/modules/sl.so"
loadmodule "/usr/local/lib/ser/modules/tm.so"
loadmodule "/usr/local/lib/ser/modules/rr.so"
loadmodule "/usr/local/lib/ser/modules/textops.so"
loadmodule "/usr/local/lib/ser/modules/maxfwd.so"
loadmodule "/usr/local/lib/ser/modules/usrloc.so"
loadmodule "/usr/local/lib/ser/modules/registrar.so"
loadmodule "/usr/local/lib/ser/modules/ctl.so"
loadmodule "/usr/local/lib/ser/modules/tls.so"
loadmodule "/usr/local/lib/ser/modules/xlog.so"
# ----------------- setting module-specific parameters ---------------
# -- usrloc params --
# use memory
modparam("usrloc", "db_mode", 0)
# -- rr params --
# add value to ;lr param to make some broken UAs happy
modparam("rr", "enable_full_lr", 1)
# ctl params
# by default ctl listens on unixs:/tmp/ser_ctl if no other address is
# specified in modparams; this is also the default for sercmd
modparam("ctl", "binrpc", "unixs:/tmp/ser_ctl")
# listen on the "standard" fifo for backward compatibility
modparam("ctl", "fifo", "fifo:/tmp/ser_fifo")
# listen on tcp, localhost
#modparam("ctl", "binrpc", "tcp:localhost:2046")
modparam("tls", "private_key", "/etc/certs/key.pem")
modparam("tls", "ca_list", "/etc/certs/ca_list.pem")
modparam("tls", "certificate", "/etc/certs/cert.pem")
modparam("tls", "tls_log", 2)
modparam("tls", "handshake_timeout", 10)
modparam("tls", "send_timeout", 10)
modparam("tls", "require_certificate", 0)
modparam("tls", "verify_certificate", 1)
modparam("tls", "tls_method", "TLSv1")
#modparam("tls", "tls_method", "SSLv23")
# ------------------------- request routing logic -------------------
# main routing logic
route{
# initial sanity checks -- messages with
# max_forwards==0, or excessively long requests
if (!mf_process_maxfwd_header("10")) {
sl_reply("483","Too Many Hops");
break;
}
if (msg:len >= max_len ) {
sl_reply("1024", "Message too big");
break;
}
if (proto==TLS) {
xlog("L_INFO","TLS Method: %rm RURI: %ru, TLSmy : %@tls.my.subject TLSpeer : %@tls.peer.subject %@tls.peer.issuer verified: %@tls.peer.verified \n ");
}
if (!method=="REGISTER") record_route();
# subsequent messages withing a dialog should take the
# path determined by record-routing
if (loose_route()) {
# mark routing logic in request
append_hf("P-hint: rr-enforced\r\n");
route(FORWARD);
break;
}
if (!uri==myself) {
# mark routing logic in request
append_hf("P-hint: outbound\r\n");
if (uri=~".*@domainB") {
if (t_relay_to_tls("sip.domainB","5061")) {
xlog("L_INFO","TLS DomainB Method: %rm RURI: \n ");
}
else {sl_reply_error();}
break;
}
route(FORWARD);
break;
}
# if the request is for other domain use UsrLoc
# (in case, it does not work, use the following command
# with proper names and addresses in it)
if (uri==myself) {
if (method=="REGISTER") {
save_contacts("location");
break;
}
# native SIP destinations are handled using our USRLOC DB
if (!lookup_contacts("location")) {
sl_reply("404", "Not Found");
break;
}
append_hf("P-hint: usrloc applied\r\n");
}
route(FORWARD);
}
route[FORWARD]
{
# send it out now; use stateful forwarding as it works reliably
# even for UDP2TCP
}
if (!t_relay()) {
sl_reply_error();
}
}
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OS specific help
Validation, confirmation tests
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Configure a UA to use TLS. Under MS Windows, good examples is Eyebeam 1.5. Make sure to choose 'TLS' as the protocol in the settings and register with the proxy. Use the diagnostic tools of the UA to see if any problems occur. Common problems are:
- Invalid TLS version: though TLS 1.0 should be used according to the SIP RFC, SSL 2/3
- Client certificate verification should be disabled
- CA certificate cannot be verified: make sure the correct chain is on the server and on the UA
- Common name of the server certificate does not match DNS name of the server
OS specific help
Reminder: this example is based on a compiled version of openSER where the config is in /usr/local/etc/openser and the certificates are in /usr/local/etc/openser/tls/user, which might differ when installed from packages.
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